Etching before paint

EWRice
Royal Aluminum Star
Posts: 313
Joined: Thu Feb 04, 2016 12:37 pm

Etching before paint

Postby EWRice » Thu Oct 22, 2020 1:03 pm

I have a scheduling dilemma between blasting my bottom and getting primer on. I know there is a way to either etch and seal after blasting, or clean and etch before priming. Searching google turns up way too many different opinions. Anybody delt with this?
Muskegon Lake
1972 32' Express flybridge
"AL13"
Twin 318s
On board air & prime 920
1963 Thompson Super Sea Lancer
Graymarine 327
1961 Alumacraft 12'
'55 10hp Johnson

jralbert
Site Admin
Posts: 753
Joined: Fri Jul 11, 2014 9:15 pm

Re: Etching before paint

Postby jralbert » Thu Oct 22, 2020 3:36 pm

You have a choice ( I was going to say you don't have a choice but you do).
#1 (preferred by far): You must apply a prime coat ASAP after blasting. Otherwise, the aluminum will oxidize -- put on a skim coat - thru its interaction with air and no amount of prep/painting thereafter will be effective. Your labor and materials will be in vain. Don't google..call the tech department of your paint mfr for their steps. Once you overcoat the bare aluminum, though, you can relax til you're ready for the next step.
#2 (also known as double work): Blast to get it pretty clean. Go away but when you come back, you have to resand to get the oxidation off and go ahead with the other steps.
Some years ago, I posted a full step by step here from my conversation with the mfr. You may want todo a search. Big project. Lots of effort but worth it in fuel savings and speed,the only real reasons you'd need to deep clean and recoat the bottom. It ain't a thing for cosmetics (but does look great when you are selling). Good luck
-joel-
former owner 1988 '32 FB Sedan
Chesapeake Bay
twin 318 / 240 hp
Potomac MD