Removing Paint

[shane-r13]

Hi All,

I just did a quick search for removing paint and didn’t seem to find an answer. Although I found out a lot about removing duck tape residue. Lol. Anyways, I have got some Johnson TD20’s and HD25’s outboards, rough shape but run, I’d like to improve the appearance and am starting with stripping the old paint and decals (whats left anyways). Any chemicals to recommend? I realize media blasting is likely the best route but I don’t have access to that so chemicals is the way i’m going.

Thanks,
Shane

[rco]

Zip Strip works very well, but is nasty stuff. Wear gloves, mask, and long sleeves. You just brush it on, wait 15-20 minutes and the paint will peel right off down to bare metal.

[nj-boatbuilder57]

Just a thought: "be careful what you wish for"

If you strip the old paint (chemically or mechanically), you’ll have bare aluminum, and aluminum is a VERY difficult metal to paint. The idiosyncrasy of aluminum is that it oxidizes immediately on contact with air, forming an aluminum oxide surface to which almost all paint will refuse to adhere. It just doesn’t "stick". The tried & true answer is a zinc-chromate primer (that puke-green color you see on airplanes), but it’s very hard to find in rattle cans, it’s toxic as hell, and needs to be applied "just so". EPA has pretty much made it go away for all but professional metal finishers. You can buy zinc phosphate prime in a can, but in my experience it’s just not as good.

If the original paint is in tact, you may be able to clean it, then degrease / prep it with naphtha and use it as an acceptable base for a modern rust-o-leum primer.

Just something to think about before you begin stripping. This may be a journey you don’t want to take….

[shane-r13]

quote NJ-boatbuilder57:

Just a thought: “be careful what you wish for”

If you strip the old paint (chemically or mechanically), you’ll have bare aluminum, and aluminum is a VERY difficult metal to paint. The idiosyncrasy of aluminum is that it oxidizes immediately on contact with air, forming an aluminum oxide surface to which almost all paint will refuse to adhere. It just doesn’t “stick”. The tried & true answer is a zinc-chromate primer (that puke-green color you see on airplanes), but it’s very hard to find in rattle cans, it’s toxic as hell, and needs to be applied “just so”. EPA has pretty much made it go away for all but professional metal finishers. You can buy zinc phosphate prime in a can, but in my experience it’s just not as good.

If the original paint is in tact, you may be able to clean it, then degrease / prep it with naphtha and use it as an acceptable base for a modern rust-o-leum primer.

Just something to think about before you begin stripping. This may be a journey you don’t want to take….

You have a very valid point. I never really thought of having trouble painting the stripped Aluminum.

[Tubs]

You can find etching primers in spray cans.
Rust-Oleum would be the cheapest.
I had used the Dupli Color on a motor I
wanted to do over as it was getting a little
beat up from use. It was a real pain to get
off before I could start over. When aluminum
gutters first came out they weren’t coated
like today. Painters would acid etch the
aluminum with vinegar before the lead
paint was applied.

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

[nj-boatbuilder57]

But most of these "hardware store" rattle-can primers just don’t work very well on aluminum. Regardless of the printing on the can, they just aren’t very good on aluminum. Fine on steel, not so much on Alum.

Zinc Chromate – works great! And you can’t get it, and it will kill you.

Zinc Phosphate – Not bad, but not as good.

"Hardware Store" (rustoleum, duplicolor, krylon, etc.) – on aluminum, they all kinda suck. Bonding to the oxide layer just doesn’t hold very well. Better than nothing, I suppose, but in my experience, "not by much".

Whatever you use, surface prep is the key. hot water & soap, then hot water, dry it, then acetone, then naphtha, then do not touch it! (skin oil un-does the washing)…..then paint immediately

[Pete]

It is available in cans but not cheap here:

https://www.amazon.com/MOELLER-MFG-COMP … B000N8LR24

More:

https://www.ebay.com/bhp/zinc-chromate-primer

Does lower price = less quality ❓

[shane-r13]

Thanks for the prep tips and product info guys. Prices don’t seem to absurd, only one small motor at this point so I’m assuming one can is enough.

[Mumbles]

Since the zinc chromate is a thing of the past now, I’ve been using PF 637 self etching primer-surfacer on bare metals with excellent results. Since it is also a high build surfacer, it will fill tiny scratches before sanding and applying the finish coat, which can be applied directly to it.

For salt water immersion, I’d prefer the chromate but two auto paint stores I went to said they can’t get it anymore. It’s NLA. The zinc phosphate would be the next choice or a two part epoxy primer.

http://ca.proformproducts.com/en/produc … er-filler/

[2fast4me]

Aircraft- spruce has Zinc chrome primer. Hazmat charges may apply for shipping

2Fast4Me

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