Cory,
here's some info about Zep
http://images.zep.com/zepcorporate/tds/psr_1063.pdf its used by tank truck cleaners to get aluminum cleaned- not shined! So that is a place where the product might be available in your area?
As to SS fasteners tapped- especially self tapped screws- that is almost assured to be a galvanic site. Even w Tef-Gel, one side of the threads' surface is metal to metal in order for the screw fastener to hold or pull on the aluminum- so there's going to be a galvanic component to those sites and passivation is about the best you'll end up doing. When fasteners have the their threads rolled or cut-in SS anyway- the stress on the surface layer does release more free iron from the surrounding molecular alloy structure. But sealing the heads along with passivating the bodies will help reduce galvanic cell formation.
I understand that hot dipped bolts is limited to a bolt/nut combo and won't be available in a self-tapping or threaded bolt size so not an option. And if access to the 'back side' of a fastener isn't possible due to design, then threads are the go-to fastener anchor.
www.longlok.com/site/pdf/selfseal.pdf this link is to a thread fastener product line that has a built in O-ring machined into the underside of the head so that it forms a heat and expansion independent seal with the surface. Not inexpensive but... a way to improve the head's seal to the paint or aluminum surfaces. They are worth your consideration as potential to eliminate water penetration into the metal to metal thread joints in tapped areas of your repairs.
I usually build old fire extinguisher bodies into blasters- that way i can get a low cost quick opening top on a very small 3-4" dia X 10-20" long 'pot' and just tap or weld aluminum fittings on the side and bottom. I'm sure any small commercial blaster would work? Just hadn't seen one small enough to do the work I was picturing of a 4" -6" circle of lifted paint? Media can be lots of different materials as long as its not 'garnet sand' (!) for steel at 150 psi! just thinking of getting a white metal level clean surface that will 'dig out' the corrosion pockets better than sanding or even wire wheel and was compact enough to get into under sole areas or bilges.
Also in cleaning up corroded or lifted paint in small areas- there are paint removers that do great preliminary work.
http://www.jasco-help.com/product/premi ... xy-remover this stuff has the dreaded methyl chloride and is noxious but... will lift almost any paint. There is a misconception that working this requires dilution water and that is not the absolute last word.
By dabbing it on like peanut butter, and letting it stand you can confine the very thick liquid to your primary area of work. Then instead of rinsing it off with water that runs every where- sprinkle a heavy coating of dry sawdust on the paint stripper. mix with a brush and the wood fibers will largely (98%) soak up the spent stripped and if you put a Scotch Brite (tm) pad on a DRILL motor with a 3" - 4" hook and loop pad while the two are mixing you will additionally scour the metal clean of paint. The saw dust acts as a very nice powdered abrasive, on the face of the abrasive pad, that lifts the partly dissolved paint film but does nothing but shin the underlying metal. That process will allow you to vacuum up the saw dust - even if its damp- and then use a damp sponge to clean any residue before using further tools to clean down into the aluminum.
This works very well to confine the patch cleaning to a well defined area on whatever surface of the boat you're working- without quite the level of mess usually associated with paint stripper. Once the metal is cleaned of paint, the work on the metal surface usually results in a dust that can be pulled out of the work area by a shop vac nozzle close by the work area? Just notes in case your work plan leaves as much of the boat serviceable as possible during the spot repairs?
Cheers,
Kevin Morin
Kenai, AK
