Been stripping paint from the hull of one of my Alpines and I'm puzzled by the treatment applied where the rivets have been ground flush on the bottom.
It appears to have filled the grinding marks and then been rubbed down or polished off before painting but my question is. . . . . What is it? It's a sort of greenish grey and must be damned good stuff because it appears to be impervious to paint stripper. Should I re-apply it before using etch primer?
I hope my new Alpine floats better than my old one!
I think that will be a zinc chromate etch primer. When it's originally applied it is almost translucent. We used to use it at work years ago, but Health & safety have now removed it. Not sure if you can still get it. You may get a reaction if you leave it on and over paint. If your planning to strip the complete boat you can get etch primers in single (cellellouse) or 2 pack. You might want to have a chat with John at Albatrossmarine.co.uk as he has looked into various paints. I used a single pack HB Body etch primer on my hull. It seems to ok, but only time will tell! Another make is Acid8 I think its a UPOL product.
Have used the U-POL Acid 8; the jury is out at the moment, with 2 outboards that I prepped properly showing issues. Another option is International's Etch Primer which was very successful to prime a stripped 30+ year old garage door 4 or 5 years ago - have had no paint loss / lifting issues on that.
Many thanks for all the advice, guys. - This newbie is learning all the time!
What I've used so far is Autotek grey acid etch primer which says it's suitable for aluminium as well as fully cured paint and fibreglass. I realise, now, that some of that finish was also present on the deck and it hasn't reacted after over-wintering outside so I guess I'm OK.
I hope my new Alpine floats better than my old one!
Chromate-based etch primers are absolutely unbeatable, but due to the health and safety issues surrounding hexavalent chromium, they're not so readily available now. HMG Paints in Manchester still do one, which I've recently used on a car I'm restoring. No idea how it's going to perform yet though!
