Hull Corrosion on Hewescraft 220 Ocean Pro

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bfetcho
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Hull Corrosion on Hewescraft 220 Ocean Pro

#1

Post by bfetcho »

Hey Alloy boat members!

I am new to posting here as I have only "lurked" or read numerous posts and forums on the subject that I am posting on. At the risk of repeating many other topics I am bringing up the corrosion issue again to get ideas to deal with my situation. I originally reached out to Kevin Morin who in my opinion is the most knowledgeable, most experienced in dealing with these issues. Here is the Private Message that I sent him along with his response. I will post pictures of my situation that I feel that I have control to fix. I also have crevice corrosion that may be too much for me to fix properly and I haven't even lifted my deck boards (water logged foam cells/corrosion?) yet so who knows what's going on under there. I thought I did my research before buying this boat but I keep reading about more issues that Hewescraft owners are experiencing.



Hey Kevin,

I've looked through a great deal of the forums searching for an answer with no luck so I am coming to you as you seem to be the most knowledgeable on the topic. The bow of my boat that is above the water line had what looked like "flowering" in an area when I purchased my used boat. It looked like the cause could have been water flowing from the holes where water from the bow deck drains. I decided to purchase the sharkhide aluminum cleaner and acid wash the boat. This took care of a great deal of this flowering that I was seeing but it didn't quite get it all. It didn't look too bad and wasn't very noticeable so I decided this process was done. I then added two coats of Sharkhide protectant to keep the look that the acid achieved. After 6-8 months I am now noticing flowering coming back and it seems to have spread. How is this possible? How do I totally get rid of this flowering corrosion and keep it from reoccurring?
Should I not use Sharkhide protectant?

Thank you very much for your time!

Re: Corrosion on Hull
Sent: Sat Jul 25, 2015 11:21 pm
From: kmorin
To: bfetcho



Brett, first let's make a bit of a review and then let's work toward a wider understanding of the various potential circumstances?

I'd like to work online at the Fourm but will reply here or in private email if an online discussion is not acceptable to you. My idea is that some of our discussions online allow others in similar circumstances to increase their knowledge and it helps the site to become more a clearing house for welded aluminum boat's information and that is a goal of the site admin and mine as a contributor.

Your flowering may or may not have been completely removed depending on the strength of acid wash you used, and I'm an advocate of the Zep-a-Lume VERY VERY EXTREMELY strong acid mix. The Shark Hide products are sort of 'home hobby' levels of acid wash in my opinion. I'm not trying to bad mouth your choices just saying my experience is that the strong acid is more effective and I won't waste my time with the weaker solutions.

We have a post on the Forum where Capt'n Dave the JettyWolf skipper; did his hull and concluded that sharkhide acid was too wimpy - but only after he'd done all the work. If you're gonna do the work, use the strong stuff in my view???

If your solution of acid was too weak to clean all the corrosion sites? then there are corrosion sites left under your new covering coat. So.. I'd say you have to strip the covering/coating/sharkehide varnish and re-etch with the 'real deal'.

Once you have a full strength acid wash the metal should be a very clean, uniform and dull grey like unpolished silver ware.... and I don't coat over that.

A note: Lots of Stateside guys are tuned to 'looks' and their trucks and cars are polished, buffed and clean..... Lots of their boats match. I'm sorry to confess Alaskans aren't all that concerned in this department so we're lousy (or worse) in regards some of the esthetics of metal finish. I've left hundreds of commercial boats raw etched and they're fine today, but the same can't be said about boats coated with varnish or lacquer.

Any non-chemical bonded coating on aluminum can trap water, promote corrosion cells and provide a path to deterioration of the underlying metal- except as recently discussed on the Forum Corrrosion-X and associated products in that line.

How can what you described happen? Your acid was too weak, too cold or not applied in concentration to allow the entire mill scale layer AND theexisting corrosion cells to be lifted and ... The rinse was inadequate and the acid film remained on the metal, and the coating film was applied when there was still water film trapped on the metal and that was held in by the coating and that is the source of your current corrosion? There are a number of conditions that would make Sharkhide into a corrosion promotion film!!!

I can't say much without being in the shop with the boat and the process-- but all of what I've described can be the source of your current problems? Its kind of hard to work off a few lines of text.

If you can, and I do understand if you choose not to.... post some pics, I'll respond and try to make sense of the pics and their relationship to your boat. It's most helpful to others if we can do this online, if not, and I understand not everyone wants to post publicly so I reply to a lots of emails privately; we could do this online at the Forum's public pages too.



Kind regards,
Kevin Morin
Kenai, AK
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#2

Post by goatram »

Your sides are not that bad. Pull the floors this winter and remove the foam. Then Wash the inside with the Acid as Kevin recommends as well as the outside. Use your PPE, If you work at Uncle Bills sign out a respirator then return it when your done, The Blue Green Gloves work well; use rubber bands and or tape to seal them. Harbor marine has the scotch brite. Napa has the Acid. When done rinse the heck out and then soap it down.
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#3

Post by kmorin »

Brett, like goatram says the corrosion shown is not very developed, it is widespread but not far along judging by the size of the 'flowers' or white chalky patches.

First it seems like the best if to find a text patch area so you can #1 determine if this corrosion OR is the lacquer just lifting? I can't tell from the photos, I do agree it looks like small crevice site but since the pattern is kind of 'worm like' or spydered and I'd expect corrosion to be more dots and less worm tacks.... I'd want to find a place to strip the hull, acid a test patch and then test for some depth to these sites?

Second, if the test patch does show there are crevice corrosion sites below the coating film, then I think that the coating all has to come off, not sure about the relation to the paint job? Did the paint job get masked and taped off when the Sharkhide was put on then it will have to be masked again to leave the paint (unless its bubbled?) and strip the bare metal surfaces.

Last, it is interesting to see the increased white flowering below the freeing port? I'm not sure why this area would have more corrosion than others? If the Sharkhide is porous to the extent it will allow water vapor onto/into the metal its sealing(?), then I suppose the freeing port (even on a trailer) will have rain run off added to any bow wash (?)and could answer why this area is more effected than others? But the bow stem? That surely is dry of the rain I've just supposed to add to the freeing port's topsides flow pattern, so I'm confused about the pattern of white we see at the bow stem.. making me think the Sharkhide may have not adhered OR the metal was still vapor laden when the coating went on?- Of course that counters the freeing port example.

When you find a suitable (least visible) location to test by stripping the film off and then applying a small patch of acid, the surface remaining is most critical to your own diagnosis of the problem. Aluminum is soft to most metal tools and so I'd recommend that in the small stripped area, after etching and rinsing with a wet cloth, drag your fingernails over the metal. What you're learning is if the surface is flat, or has a small depression where the white area was? In other words you'd strip a small area so that you can make decisions about when and where you do more to the whole boat.... and after acid etching that entire chemically paint stripped area, you'd learn if there were actually pitting? A strong shop light at an angle close to the surface would allow you to see scratches and pitted areas too.

At this point, I'd only expect to see a few thousandths or even one thou. depth of any pitting. But it's important to make sure these are crevice corrosion sites, which you and most of us suspect they are....... not paint lifting sites as the could be.

Hope this helps some... goatram's right though the bilge may have corrosion going too? Does the model designate a 22' LOA boat? If so, I don't think foam is needed (CG reg's for flotation stop at 20' LOA if I'm not mistaken?) so pulling it is a good idea. Does this boat have an integral engine 'box'/mount/extension or who are the engines mounted? I've see a Hewes with an odd arrangement where the engine mount was bolted AND welded to the hull and I was kind of confused by that, but that boat did have interior corrosion in the bilge and it was less than 10 months old when I was asked to look.

What does Hewes say about your pictures? Are they able to tell you if this is the Sharkhide lifting OR crevice corrosion under the coating? Even if you bought the boat from another owner it would seem to me that the builder would want to solve this problem - as much as you do? I'd think that went double if you've been reading about Hewes having widespread corrosion on their boats? ( But what I think rarely has much to do with what other think so I'm just speculating. )

One of the pictures seemed to show a little dock rash and some 'etching streams' or color variations, but not much white flowering - is that just because the lighting makes that image harder to see the white flowers?

Cheers,
Kevin Morin
Kenai, AK
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#4

Post by bfetcho »

Thank you Goatram! When I first used the Sharkhide brand aluminum cleaner, I did not tape anything off as the owner said it would not effect the plastic decal above the metal that I was treating. Obviously the Zep-a-lume is much stronger so you are recommending taping off areas that I don't want the acid to hit?
Also, I have tried calling Napa and a few other places to find the Zep-a-lume and none of them have it. Are there any alternatives or other places that might carry it in WA?
You are also suggesting scotch brite pads; Would I being using these before after or during the acid wash?

Kevin,
I have not contacted the manufacturer about this hull corrosion. I have however contacted them regarding the crevice corrosion under the paint (separate issue). They told me that the paint is warrantied for 2 years and they could not doing anything about it besides recommend a company that could fix it. I guess I figured I would get a similar response so I search the forums first.

Regarding the various patterns of flowering, I don't quite understand it. The flowering under the freeing port was the one area when I acid washed, it would not clean like the rest. Could it have just been severe water staining that the acid was not strong enough to react with or maybe its a deeper corrosion?

The boat is 22' with a 2' extended transom bracket. I believe you are correct in saying it does not require the foam. I have read other posts including on the Hewescraft forums that when people pull their floor boards, they find foam saturated with water. I will be checking this at some point to assess the possible problem.

Yes, one of the pictures showed dock rash and the etching streams. The flowering is there, just not the best photo.

Brett
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#5

Post by goatram »

bfetcho wrote:Thank you Goatram! When I first used the Sharkhide brand aluminum cleaner, I did not tape anything off as the owner said it would not effect the plastic decal above the metal that I was treating. Obviously the Zep-a-lume is much stronger so you are recommending taping off areas that I don't want the acid to hit?
Also, I have tried calling Napa and a few other places to find the Zep-a-lume and none of them have it. Are there any alternatives or other places that might carry it in WA?
You are also suggesting scotch brite pads; Would I being using these before after or during the acid wash?



Brett
Napa has Aluma Brite. I use that. The Zep A Lume Might be at Motor Trucks @ the southend of Hwy 529 Right along side of the Snohomish River and bridge at Marine Drive.

Use Aluminum Tape to seal your pain-t. I would use the scotch Brite with the Acid. Rubbing it fore and aft not in a Circlur motion. The For and Aft motion should keep the Natural Grain Look going. I also would use Green Pads Not Red ones.. White ones are Fine and will polish the aluminum.
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#6

Post by bfetcho »

So, I spent a whole day getting all the Sharkhide off with lacquer thinner. This was not as easy as the website would make you think. The next day I am prepared to acid etch the boat with 2 gallons of Aluminum brightener from NAPA(this was the best I could get my hands on), Scotch brite pads, and the proper PPE. I used all of the 2 gallons of undiluted acid cleaner and scrubbed an area of the hull with scotch brite. This was also an all day project but this one looks like it did not yield the results I was expecting. The surface looks worse than before. I tried doing the fingernail test that Kevin talked about but I only felt my finger nail catch in a few places.
Any thoughts on what I did wrong? Is this acid also too weak? There is one picture where the hull looks strangely stained, I'm not sure what happened here. Help!

Brett
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#7

Post by goatram »

Sent you a PM. Two Gallons used would have should have it clean as a whistle :shocked:
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#8

Post by kmorin »

Brett, I'm not sure the lacquer got all the Sharkhide off? I see the same white flower patterns - are these "After" photos? they look suspiciously like the "Before" photos!????

I think it would be a good idea to describe what happened when you used your acid? Did the entire surface turn to foam like dish suds? then the foam sort of 'melt away' and finally did the rinse water expose super dull (sterling silver with no polish) - visually things are not right?

I think a full on, toxic, and dangerous paint stripper is the first step in a test patch??? I'm not buying into lacquer thinner because I think it will evaporate before lifting the fully dried lacquer??? I'd want the paint on goop type, toxic, stinky, (the dangerous stuff not water-and-orange juice silly hobby junk), burn your skin if you're not covered- holes in your blue jeans if you don't wear oil skins... that stufffffff! Jabsco's toughest, that you need to wear a breather to open the can....

Now I'd spend time getting full on Alum-a-brite OR Zep, and some real paint stripper and see if there is not some change to the surface.. At this time,based on my quick glance at the photos, I'm voting the Sharkhide is still there. Dont' know that but I can't see an etched aluminum in the photos -yet.

Cheers,
Kevin Morin
Kenai, AK
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#9

Post by bfetcho »

Kevin,
I used an automotive thinner that I got from NAPA. I put the thinner in a spray bottle and sprayed it onto the aluminum and wiped it off with a paper towel. I thought I got all of the Sharkhide, there were a few small spots where I knew I hadn't got all of it after the acid process. The metal did foam up when I sprayed the acid on just as you described. I basically did the boat in six different parts, I would take a section and spray the acid on until it was coated in white foam and then resprayed to keep it that way for at least 15 minutes. Yes, the metal is a whitish color even though it was a similar color because I already used the acid etch before I applied the Sharkhide. Yes, these are "After" photos; the boat looks worse...

I will try applying some strong stripper to make sure that the sharkhide is gone.

Brett
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#10

Post by kmorin »

Brett, I'm at a loss, if the photos are after, how would the white flower patterns remain if the underlying metal were truly etched? So if the acid did foam up, indicating that the metal's aluminum oxide was being 'etched' or acid combined, then was rinsed and the white concentration remain, now it seems to contradict my experiences quite a bit?

In my experience, exclusively with Zep-a-Lume as the etchant solution, I've seen the "white spots" removed totally, I've not seen any case where they remained after the acid acted on the metal surface- so that lead me to ask if the lacquer were totally gone/removed? But if the acid foamed, it would seem to be the reaction with metal and that implies the metal was clean of Sharkhide, so that leaves me to my confusion.

Now, I'd suggest a hand lens, or magnifying glass as a tool for examining the surface and a high intensity work light, or out in good sunlight. The idea is to get a real world exact look, really close up look at these white flowers to understand why they're persistent? IF the acid was too dilute? so it was ineffective in etching/cleaning/scouring the oxide and with that layer the corrosion sites (? this is my opinion still) THEN more concentrated acid after more concentrated effort to surface clean of any paint films seems to me a good path of work.

In the mean time why not get some Scotchbrite pads (TM 3m Corp.) either hand held OR power pads, they are available in 2" dia. for a drill motor, and buff a patch of the hull with white flowers? What this does is make sure we're down to metal, not guessing, no maybe but full certainty.. by buffing till the scratch marks are showing on the metal.... NOW! are there any white flowers left? I'd hope not, so put the acid on this mechanically cleaned area of the hull. When it foams and is rinsed, that is what clean aluminum looks like!

Buffing the hull with buffing pads will leave patterns that may be cosmetically unappealing but if the only stripper you use leaves some ShkHide layer intact(?), and the acid doesn't get to bare metal and even then-- may be too weak to clean all the corrosion sites- no white flowers left!!- perhaps you'll need to use a mechanical device to clean up? Rotary pads for grinders from 2" up to 7" are available.... Belt sanding belts for different sized sanders are available and using a hand pad on the etched area while the acid is freshly reacting are all methods of cleaning the metal to a 'base metal layer'. IF you have a good air compressor then using Scotchbrite hand pads on a 'jitterbug' (pneumatic) type handheld sander, or a pneumatic "long board" might also help deliver a better or more uniform lengthwise pattern of abrasion?

My take on the coloration of the patches of the hull are the oxide or ShkHide retained some form of metal salts from whatever water its been in, and the acid reacted with those and formed color patches? Another indication that perhaps the chemicals being used are not adequate for the job.

Brett, many posters here have said repeatedly, " I can't find this product..." or .." that's not available in my area" or ..." this is a good as I could find" and it's important to note that what I'm posting about is my experience with the chemicals I list. IF you don't go to the full effort and succeed in obtaining the industrial strength chemicals, or they're prohibited for private use by the local regulations on your life, then what I have to say is sort of not applicable to your circumstances. I think goatram's idea was that Zep or the stronger acids might be available at (line haul tanker) truck trailer cleaning companies? I know that was Zep's advertised reason to sell the stuff!

Brett, if someone posts that they're making a new fuel tank for their boat and they've decided to use Home Train Station's "magical aluminum soldering kit" instead of TIG welding.... well, right away there is going to be some skepticism about their success. There are tools for the job and there are home hobby levels of effort, to get this job done, in my experience there are useful tools needed, and I'm not sure you're employing the correct tools -yet?

cheers,
Kevin Morin
Kenai, AK
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#11

Post by engineroomeddie »

Worst case scenario, sandblast it, epoxy prime it, and powder coat it in bottom coat.
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#12

Post by kmorin »

Brett, rereading you earlier posts specifically about
bfetcho wrote:I tried doing the fingernail test that Kevin talked about but I only felt my finger nail catch in a few places.
That is enough to confirm the white spots are initial corrosion sites. If they were made by Sharkhide lifting adhesion and leaving a small discoloration then there would be no surface erosion to catch your nail. So you do have initial corrosion and if the underlying, original aluminum were not fully etched to remove the mill scale, which holds water vapor in that film? then the Sharkhide would have to have been applied to a somewhat heated surface, to dry out the vapor retained in the mill scale... and that does not appear to have happened?

Therefore, the sharkhide in combination with mill scale would promote the combined conditions needed to have crevice corrosion, the film (Sharkhide) to trap in vapor and the mill scale to hold that vapor on the surface while it was paint prepped combined with the lacquer reducing access to more oxygen to 'heal' the aluminum's oxide layer so; the vapor provides an acidic droplet to being the crevice site cell's growth, the film keeps it going by keeping the site from rinsing freely and reoxidizing and the result is "you got flowers".

Image

here's the side of a 30 yr old net skiff, its covered with years of mud, blood, guts and fish slime decorated with scales (white spots) but not one corrosion flower, the stains and discoloration are because its just rinsed now and then not etched that I know about, but is coated with fish fluids as they come over the gunwale- so what I'm pointing out is the finish could be more attractive with some work but this shows the correctly cleaned 5086 H-116 aluminum finish!!! "bare as a baby's butt" so to speak.

Image

Same skiff viewed 180 from previous photo. I don't know what was leaked down the topsides of this skiff? Looks like acid was dripped over the side years after the build? But this could be some white liquid since the boots on deck have wiped it clean just above the deck at the bottom of the drips. Anyway, this does help show what 'old' etched aluminum could look like vs newer 'whiter' etched material. A bare boat can be etched anytime, every year if that were important? and the result is a 'fresh white paint color' but no damage to the metal... what damages the metal is corrosion from water held in a thin film, starved of oxygen or galvanic site corrosion where there are two different metals in contact -and wet. [NOTE: two vertical pipes at the bow tank are not my work!]

Image
This photo of a cabin that was built outside the hull shows a nice visual confirmation of white metal etch. The cabin is raw aluminum etched correctly. There is NO coating on the outside of the cabin in this photo; but it is painted inside.

The tank below the windscreen bolts to the cabin to complete its shape is deck mounted/cabin mounted and is not etched in this photo. The tank's sheet was buffed in a 50" wide drum sander before forming/welding so it has most of the mill scale removed mechanically. There is a patch where the buffing was less complete to show patches of mill scale along the lower edge. So... here are all three 'looks'- mill scale almost intact, mill scale mechanically removed and mill scale chemically removed to white metal. I'd say whatever results you get on your boat should be compared to this white metal finish- if you're not there: keep going.

Think paint stripper and Zep! or some mechanical mill scale removal THEN some Zep?

Cheers,
Kevin Morin
Kenai Ak
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#13

Post by kmorin »

Brett, Forum readers following this topic I'm posting this next photo because it has a better view of surface preparation comparison.

I built a 25' skiff a few years ago, the entire hull panels and all parts of the boat were put through a 50"wide drum sander with a hook and loop strip of ScotchBrite - like (not 3M brand to my knowledge) on the drum to mechanically clean the mill scale to help remove some of the handling markings on the sheets from the supplier- who usually does a better job of transport but marked this set of sheets.

However, the deck was fit of pieces too large, in both directions, to fit into the drum's 51" max width, AND the deck would be painted with some traction paint after being etched and taped off ... so..... the deck was hand buffed using a 7" ScotchBrite (tm) pad in the brown or coarse grit, on a grinder.

The reason to post this photo is to show
#1 the hand buffed deck- random pattern with circular power tool
#2 to show the not scratch finished house- just chemical etch,
#3 & #4 and then two levels of the tank as posted above. The tank's upper section was cleaned in the 50" drum pretty well but the lower edge didn't clean as well so there is mill scale (chrome looking finish) remaining.

All four surfaces we've been discussing are shown and that makes this worth the post to be able to make a comparison, IMO.

Image

Cheers,
Kevin Morin
Kenai, AK
Last edited by kmorin on Fri Jul 31, 2015 6:16 pm, edited 1 time in total.
Reason: typo's as usual!!@(*&^&%!!!
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#14

Post by icondonj »

I'm no expect on this subject, and I've never had to do this after having applied Sharkhide, however I probably spent about 30 hours last year trying to get all the flowering off my boat and a trick I stumbled on was to apply some 3M aluminum polish with the undiluted acid wash (I used the toonbright product). I realize that doesn't really make sense, but having a thin layer of polish on the aluminum and then applying the acid resulted in an enhanced reactive foaming that was noticeably better at removing the flowering than using the acid alone. Assuming you have removed all the sharkhide, this may be worth a shot.
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#15

Post by kmorin »

icondonj , can you elaborate just a bit? I don't know about the compound you're referring too, but if it will enhance the etch it is a very worthwhile bit of knowledge! Do you happen to have a link, you could post? toonbright is news to me and might be to others, not sure what it is, but sounds like something worth the time to learn more about.

Cheers,
Kevin Morin
Kenai, AK
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#16

Post by icondonj »

Products used -
3M Marine Aluminum Restorer and Polish paste, Toon-Brite Pontoon & Aluminum Cleaner. Also used fine bronze wool pads with some barkeeper friends cleanser in the heaviest flowering areas as a mild abrasive scrub in the acid foam. The method that worked best for me was to apply a small amount of the 3M paste, hand buff, apply the acid, and then slightly scrub with the wool and hose off. I worked in about 3 ft sq sections at a time. If I had done that the first time, I think I would have drastically cut the time it took me to remove the flowering. I made a post about 14 months ago on this with a couple photos. My flowering was worse in some areas than the photos in this post, but I didn't take any photos of it. Also, I used a lot of sharkhide to complete the job. 3 coatings. 14 months later the boat still looks good.
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#17

Post by Chaps »

icondonj wrote:I'm no expect on this subject, and I've never had to do this after having applied Sharkhide, however I probably spent about 30 hours last year trying to get all the flowering off my boat and a trick I stumbled on was to apply some 3M aluminum polish with the undiluted acid wash (I used the toonbright product). I realize that doesn't really make sense, but having a thin layer of polish on the aluminum and then applying the acid resulted in an enhanced reactive foaming that was noticeably better at removing the flowering than using the acid alone. Assuming you have removed all the sharkhide, this may be worth a shot.
You're right, it doesn't make sense that applying acid onto a surface that is covered in some other totally unrelated product would work so well but some great discoveries that benefit all of society were a result of accidental mash-ups. On a side note, I have a boat coming in to the shop next week that the owner restored simply (apparently) using 3m pads of varying coarseness on an orbital and in the pics he sent the hull looks great so I'm looking forward to sharing his technique when I find out the details.
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#18

Post by goatram »

No Bronze wool pads Should be Used. Red Scotch brite is course, green is medium, White is fine, This is what you should use to help clean. Kevin has also recommended heating the area prior to applying the acid. The Coarser you use requires more polishing to restore to a shine.. If you rubb for and aft you will be working with the grain of the metal. Much easier to polish than if you use a orbital sander. As Kevin has attempted to say you have not removed the finish. The Chemical softens it but unless you continued to change wipes the wipes will just smear it around. Chemical Stripper or Mechanical Stripping is required. I Use the NAPA Aluma Brite and it works on Bare Metal. Use of two Gallons is wild. I have used less a gallon on a 22' Raider's Bilge and cleaned out a ton crap and it looked bright as new acid washed Aluminum unmalested by Shark Hide.

Your Results don't compute in my brain. Do some more homework. :deadhorse:
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#19

Post by bfetcho »

Thanks for the continued support everyone.

I have checked to make sure I have all the Sharkhide off of the boat with a couple methods. I tried using the Jabsco paint remover and letting it sit on the surface for 15 minutes as the directions suggest and I got nothing coming off of the surface. I tried this is many areas with no results. My next step was to use scotch brite pads to ensure I was down to metal. I am definately down to metal as I now have a brushed look instead of the white like I had before. I have been scrubbing pretty vigorously by hand with a maroon (320-400) 3M scotch brite pad and I see some result. I could go with a more course pad but I don't have one so I'm using the maroon. At this point I am committed to the scotch brite and then I will work my way up to finer grit wet sanding paper as I do not care for the brushed look. The problem is I don't want a polished finish either so I'm not really sure how to get it back to the white bare aluminum finish. I will probably end up using the aluminum cleaner again somewhere in this process. I found a new cleaner at O'Reilly's auto called Brite Alume by KO manufacturing.

I spoke with the owner of Sharkhide and his thoughts are that the acid wash will in no way get rid of the "corrosion" (he has never heard or the term flowering) totally and that wet sanding would be the only way. Just thought I'd throw that out there.

My next concern is after I kill myself trying to sand out all this corrosion, what's to say that it won't come right back? Hopefully all this started when the mill finish was on the boat and now that it's not, it won't com back.
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#20

Post by kmorin »

bfetcho,
Of course we may be using a term that is made up on the internet (whiter flowers) but the owner of Sharkhide could maybe glance at your photos and reflect on what he calls that condition of the metal's surface??? Of course the acid wash, sufficiently strong acid wash will excavate the surface corrosion sites, as I've seen and done since the 1970's so I'm not really willing to accept his opinion over my own experience on that point.

Sanding, regardless of grade, is a mechanical removal method, and leaves bare aluminum in the "bottom of the furrow" as it tracks grooves over the metal's surface. That bare metal becomes covered in oxide in a few seconds, unless its wet? Then the oxide forms when the water dries off and the air gets to the metal.

Of course wet sanding is little or no different than using ScotchBrite (tm) pads of any grit, they're just longer lasting and much more waterproof than even wet/dry paper. So that method is working and if there is no Sharkhide on the hull and the sanding is removing the (perhaps mis-termed?) white flower patterns then you hull did have some initial stages of corrosion. I know that is has been labeled as galvanic by a spokesman for the builder (***) however... unless the original mill scale is actually chemically (galvanically) different from the underlying metal's location on the galvanic scale (??) then; I think if follows that the corrosion was crevice corrosion from a film of mill scale or (AND) Sharkhide applied over mill scale with water vapor still entrained in the mill scale.

My take is the sanding is a method of removing the entire outer film of Metal+Oxide+Millscale+Lacquer+Paint if any of these are present and it leaves bare aluminum. If the bare aluminum is left alone it will oxidize and not corrode, if you need a finer finish then you'll have to keep grading up the grit # until the lines/scratches/patterns disappear to the naked eye. That might be at 1200 grit or so, and in my experience I found I could not really skip or graduate the grits more than 100 per step below 400-500 but I could move to 600 then 800 and 1100-1200 in those steps and still not leave a layer of scratches so coarse that they are seen.

I'd get a long board, jitter bug, or some other power tool because the standard you've set is high,
bfetcho wrote:At this point I am committed to the scotch brite and then I will work my way up to finer grit wet sanding paper as I do not care for the brushed look.
however, just a reminder about the white metal cabin shown above; that metal was all brushed to about 120-140 to remove mill scale and was then acid etched to white. So the "brushed look" does get reduced visually by a strong acid wash.

However, as a reference to the surface; once you start scratching aluminum (sanding) the only way to flatten it back to near original is to keep sanding until the finest scratches (sanding marks) are not really visible. I think you'll have to get some different grits and a piece of scrap and make some tests to learn what level of 'finish' your eye needs to be happy with the boat's look?

I have no experience with KO's Brite Alum product so I can't remark about its strength and cleaning effects.

I'll guess you've had no luck finding Zep-a-Lume wash and that is why you're using the other products? Whenever washing with acid, its good to use a plastic yard type weed sprayer, use the acid warmed up if possible, the boat in the sun, if possible to heat it, I regularly use a propane weed burner to heat the hull here in Alaska, and make long spray paths horizontally beginning at the chine or underneath on the bottom and working up overlapping each spray pass, otherwise you will get white drips as vertical streaks. However if you apply 'fresh' acid as you ascend then the overlap will mix with reacting acid, but if you start top down the drips will have already reacted and that causes the streaks. I've found they can be removed by etching a couple more times over the same area.

IMO the key is to etch with a sprayer and do it bottom up in arm's width patches along the hull, with full gear on to protect you. Then it foams up, you can scrub it with abrasives but if you've already sanded to a finish the don't scrub, just spray and finally rinse; move down the hull a yard or arm's length and repeat, this should give a white metal etch, if it does not then the acid is not concentrated enough you'll have to use a second or even third etch to get a white metal finish, which is why we use Zep.

*** I got in contact with Hewes Marine who has a policy of not remarking online because their method of solving problems is with each individual owner. Their spokesman did think that my verbal description of the corrosion was 'galvanic' corrosion and that may be true, I'm not fully versed- chemically educated in the mill scale composition so what I'm interpreting as crevice corrosion may be galvanic if the mill scale is a finish with some metal or even an alloy of aluminum in the finish that has a galvanic difference with the underlying metal?

So AAB.com Forum readers and members; If you have any issue with a Hewescraft boat- contact them directly as they have people there interested in solving problems with their boats.

Cheers,
Kevin Morin
Kenai, AK
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#21

Post by Mjglawrence »

Thanks for all the information on this flowering issue. I am working on a 22' Almar Sounder.
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Never heard of this product either.
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Re: Hull Corrosion on 2010 Hewescraft 220 Ocean Pro

#22

Post by kmorin »

for everyone reading this thread:
I'm not sure if the MSDS (material data safety sheet) of any of these products are well understood by the posters or readers but there's a reason to find them, and see if they could help understand somewhat, more about the chemicals involved. MSDS sheets should be read closely before fiddling with Zep's product, and its a good idea to ask for an MSDS for any new chemical you buy.

Stronger acids mean more concentrated acids, a mixture of acids may also add additional cleaning power to the liquid and last; the more concentrated an acid the more water could be added to dilute and weaken the mixture so that a range of aluminum cleaning can be achieved. The low range is to remove some dust or pond scum build up, but the higher ranges can be the complete removal of mill scale and even excavate exiting corrosion sites' pitted bottoms to help arrest future corrosion by removing the 'cells' contents.

When any of the products are posted, and suggested, its most helpful to find MSDS (federal law requires these for almost all products- especially acid!) sheets and see if you can link them in your post so that others can compare the different products at the chemical level.

http://www.interstate-roofing.com/uploa ... 5B2%5D.pdf here's a link to Zep-a-Lume for example. If you read this MSDS you'll see that inhaling this stuff could kill you, getting it in your eyes as a mist can blind you, and if left on your skin can burn you. (But is sure does clean aluminum!!)

How many hardware stores want to stock something that can kill? I'd guess not too many given that many people don't know what the PPE acronym even stands for??? (personal protective equipment) So, while I'm advocating using this super strong acid mixture, I'm also saying it can't be used except by prepared and well equipped boat owners. If you're not experienced in hazardous chemical use, either get some training or pro help- or just stay away from this stuff.

What may show up in the links to other aluminum cleaners is the % of each type of acid? Here, Zep's mixture has up to 20% of sulfuric acid, and up to 10% phosphoric acid as well as another acid! If its mixed 30:1 with water, diluted, then the amount of 'raw' sulfuric acid you'd spray on your boat is greatly reduced by dilution. However, if you purchase a product not intended for (only) professional use, that contained only 3-4% of this volume of acid- and diluted that- you'd end up with a vinegar solution cleaning your boat.

That's fine, and vinegar will clean your boat, it just may take half dozen (or many more) applications before you get the same results as with one washing of Zep. But the vinegar is very safe by comparison so anyone reading needs to keep that foremost in mind.

My post is to call attention to the MSDS for each product, without these Fed. mandated documents we don't know what we're comparing? Surely pulling a 26' welded trailer boat with your Cummings Turbo Diesel P/U is not the same as pulling that same load with a 1968 VW Bug !!

I'm trying to make sure we hold an apples-to-apples discussion and not cause confusion on the overall topic of acid etching solutions? These products have to beranked/graded/grouped by the concentration by volume or weight of acid they contain.

Thanks for
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Re: Hull Corrosion on Hewescraft 220 Ocean Pro

#23

Post by bfetcho »

I started with the maroon scotch brite pad over the whole boat and made a little bit of progress. I then sanded with 600, 800, 1000, and finally 1500 all by hand because I am gluten for punishment. After this I took the full strength KO Brite Alume and acid etched three times. Here are a couple not so great photos of the look. The metal definitely turned white and looked great although it did not get all of the "corrosion." After the boat dried and sat in the garage for a day I decided to take these pictures and it appears that there is some streaking which did not show up right after the wash.

Kevin,
I am familiar with hazardous materials and I have all the necessary PPE to use any of these chemicals without risk to my health. Yes I have looked for the Zep Alume and I have been told by several people that I need some kind of license to purchase and use it. I am still working on getting the MSDS for the Brite Alume that I used but I am sure as with all the other stuff that is available, it is a weaker solution. I compared the NAPA product that I used to the Zep Alume and yes, there is a big difference in concentration.

As far as my application is concerned, do you think I left the acid on too long and it started to dry and that's why you see the streaking or is this just the oxidation? When you apply the acid, how soon do you rinse it off?

Also, since I still haven't gotten rid of all the corrosion sites, would it be a bad idea to polish the metal? I will either polish the metal to enhance the appearance or I can try etching again and again until the "corrosion" is gone.

Brett
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Re: Hull Corrosion on Hewescraft 220 Ocean Pro

#24

Post by kmorin »

bfetcho,
I didn't realize that Zep took licensing, but I can understand that in some locations where there are lots of people and the officials a super cautious about materials as corrosive as Zep's aluminum cleaner. I think the coarse sanding, back to one of the earlier grits will remove all the corrosion, but so will Zep.

My reasoning about sanding the remaining corrosion sites is they are 'below' the surface, deeper into the metal. So rather than take time to polish which removes the tiniest film of metal and smooths most of what remains.... I'd go back to the coarsest grit you want to use (and eventually buff out!! You're a true glutton for punishment or at least not shy about hard work in big volumes) and clean the surface evenly until it was all uniformly traced with that grit's scratches and no corrosion site coloration. Then graduate the grits as you've already done (true glutton for work) and last, I'd etch the final surface if I wanted white metal. Now, if you want shiny; polish with the cotton buffer and polishing compound.

So maybe the shortest route is to find a truck tank cleaning shop -they've got the license, see if you can use some of their Zep on their site?? OR you may have to move back to a coarse enough sanding grit to cut more of the surface, with a deeper layer of removal to "peel off" the depth of the corrosion you're got?

Glad you're tuned to the correct PPE, and you know to handle any of these solutions with caution, care and circumspection; good health is worth infinitely more than a pretty boat hull.

I leave Zep on for about 3-5 minutes, or until the foam starts to subside, when the foam starts to clear away from a uniform coating, I begin to rinse with a hose. I attribute streaking to uneven acid etching, where the more etched an area is the whiter it is, to avoid streaks I work bottom up and that has always kept the streaks from forming. I'd say the strength of the acid is lower, so the speed which you can etch has to be slowed, that is a bottom spray line of 6" 8" wide along the chine needs maybe a minute before the next line is added?

My reasoning is that the acid dripping onto un-etched metal seems to be concentrated in the drip, that means the area under the drip gets more whitening/stripping/etching action; to avoid this I'd say maybe let the acid work on the horizontal band of one even sprayed strip and wait 'til it foams up, which is nearly instant with Zep but may be a few seconds with a less concentrated product - implying that you'd spray count to 20 and spray above???

I don't see the streaks as leaving the acid on too long, I see it as uneven reaction on the surface where the whiter area got more oxide removal, when the removal is at a higher rate with stronger acid, the uniform white is more often the results but I've used and had streaks when I allowed freshly sprayed on acid to flow down to areas that had less acid OR were dry.

Hope this helps, my reasoning could be faulty (often is) but others may have more experience with this level of finish that would be more helpful to learn? I did have one owner turn his boat over to a body shop, they cleaned it with sand paper to a fine grit then polished to a chrome finish! It was the brightest skiff I'd ever seen and you had to have on sun glasses to even stand near it! That was all done with power tools and the boat was new, but it sure was shiny!

cheers,
Kevin Morin
Kenai, AK
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Re: Hull Corrosion on Hewescraft 220 Ocean Pro

#25

Post by bfetcho »

I have contacted ZEP and it looks like they will direct ship to me if I wish. They smallest quantity they sell is 4 gallons but this might be worth a shot considering this has worked so well for Kevin.
I have also found the SDS for the KO Manufacturing Brite Alume which is fairly similar to the ZEP-A-Lume. Here they are side by side for comparison:

KO---- ZEP
Hydrofluoric Acid ( <6% ) ( 5-10%)
Sulfuric Acid ( <25% ) ( 10-20%)
Phosphoric Acid ( <5% ) ( <5%)

Many of the aluminum cleaners that are stocked on shelves and are readily available do not have the hydrofluoric acid in it because of its toxicity and high health hazard. I used the KO at full concentration so it seems like I should be getting a similar result as the ZEP. Sanding might be my only option...

I also wanted to mention that I reached out to Hewescraft a couple weeks ago and they are working on trying to get an answer to me. They have contacted the owner of Sharkhide to get some information about his product that might help Hewes come up with the best answer. I do have to say that every time I have contacted Hewescraft, they have been very helpful and seemed like they were concerned with wanting to help get to the bottom of any problem that I might be having.
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