best acid wash / primer for mercruiser aluminum sterndrives?

[Jeff]

I'll be cleaning up the transom assemblies, etc. of a pair of mercruisers next week (zincs were missing or corroded 3/4 away, so transom assemblies now have some flaking/powered aluminum that needs to be sanded and repainted.)

When I did this 10 years ago I used Interlux primewash yellow zinc chromate primer and then if I remember a purple Interlux aluminum primer (but I don't see that can for sale any longer) and then the black topcoat. That was a long time ago though (thankfully I guess!)

I see Quicksilver sells a "Mercury Mercruiser Phantom Black Paint" but I'm not sure what this is -- am I correct it's just an enamal topcoat? I'm not seeing a QUicksilver primer/wash to go with their phantom black touchup kit.

What's the best aluminum wash/primer/paint going now for refinishing mercruiser outdrives?

[mydauphin]

I would sand aluminum down and spray with Zinc Chromate paint right away. Or used Alumaprep acid and Alondine (I forget exact spelling and still Zinc Chromate). Then I would paint epoxy paint or good outdrive paint.

[Guest62110524]

use fast foaming hydrochloric THEN HOSE, WHILE STILL DAMP SPRAY ON or brush, spray from PLASTIC spray , alodyne, which will turn bronzy, it,ll stop oxidization, then paint with 250 microns dry of awlgrip or allcraft or altex devoe number one Alodine is used a lot in the aviation secter, it works, a very old trreatment, and provan, only on the yachts I build and treated this way ddi I have no problems By way there is no need to paint after this treatent, take as long as you wish
I dug this up
and the reason you do not apply through metal is that it will not TAKE
tHOSE WEE GARDEN SPRAYERS ARE BEST, HEAVY SAND FIRST AS DUAPHIN SAid
http://www.finishing.com/124/66.shtml

[Jimbo1490]

I can report that the new kid on the block, Prekote, works very well and provides reliable adhesion. The manufacturer recommends it to be overcoated with a high-solids epoxy/chromate primer. This is a NON-TOXIC alternative to acids and chromic acid conversion (Alodine).

Alodine is very toxic and contains heavy metal salts with fairly high 'bio-availability'. If you use it, you should protect yourself from exposure, but also capture all the run-off as it is a persistent groundwater pollutant.

Jimbo

[mydauphin]

Originally Posted by Jimbo1490

Alodine is very toxic and contains heavy metal salts with fairly high 'bio-availability'. If you use it, you should protect yourself from exposure, but also capture all the run-off as it is a persistent groundwater pollutant.

Jimbo

The stuff is nasty, imagine hosing a down 75 foot yacht with acid twice, then Alodine pouring out a sprayer... Gallons and Gallons... Then washing again.
But it works real good against corrosion but it is really bad for environment.

The Miami river has had many a boat yard since WWII and is so contaminated with Arsenic, Chromates that no one, I mean no one in their right mind will dive in it. Even with protective suits the county and city divers refuse to do it.

[gonzo]

The acid prep is available at any auto paint supply. They use the same thing for truck boxes.