Repainting a plywood/epoxy hull

I'm considering the purchase of a plywood epoxy cruiser/racer... probably early '70's. It's in fair condition, but has 30 years' worth of paint (badly applied!) inside and out. It's difficult to tell if the paint is regular household enamel, or a fancier marine-grade product. Can anyone give me any advice on removing marine paint? Are there chemical paint removers that work on Awlgrip/Interlux etc. , or would I have to sand it off? Would a heat gun have any effect on the paint? Would a heat gun damage 30 year-old epoxy?

Also, if I wanted to do some modifications/repairs to the hull would there be any compatibility issues between the epoxy used 30 years ago and modern products?

Any comments or advice will be appeciated.

Dave

 

Epoxy will soften with a heat gun. You might try it in an inconspicuous location to test it out.

My guess is that you're stuck with sanding (or sandblasting), but at least then the surface will be prepped for new paint.

 

Thanks. I never thought about sandblasting...

Dave

 

It is true that, unless you are very careful, the epoxy will soften and probably blister if you try to use a heat gun. If you try sandblasting you will only have to sand and fair the hull once you are ready to paint anyway. Sandblasting generally produces a very rough and irregular surface. Quite often there are areas in the layup schedule that are not as heavy (read thick) as the rest. Odds are that you will probably blow through to the plywood at some point. The most efficient and effective method in my experience is to use a good sharp scraper and then finish with various grits of sandpaper on a random orbital sander. Porter cable makes a good one. Just remember to take accurate measurements of your waterline from the sheer/deckline or scribe it in before you remove all of the paint. Enamels are easier to remove than polyurethanes. If you find that the paint is difficult to remove, then sanding with more aggressive grits is a distinct possibility.

 

I agree with DR.J
Sandblaasting or power washing on plywood will remove a layer of the ply...not good. There's also a number of good heat guns for removing numerous layers of paint.

 

Dave E, check to insure it's epoxy. The early 70's had plenty of epoxy use, but lots of folks were still using poly, unconvinced it wouldn't stick.

Don't use heat and don't try sand blasting, this isn't a rusted car body or something that needs that aggressive of material removal. Pressure washers are for boats built of other materials, not wooden. I've personally seen large chunks of wooden hull blown off, with the use of a pressure washer.

There are several environmentally kind strippers available and some less nice. Of course the less nice ones work the best, but may screw with the epoxy or poly sheathing (soften it) So try the ones that are rated for use on fiberglass, which will be formulated differently then the others. It's better to use two or three applications of this goo, then one heavy try at it. This stuff is nasty and can do lots of harm, but it beats the hell out of sanding.

Nothing will keep you from having to go over every square inch of the hull with a sander. The stripper will work wonders (if done right), but will leave areas that need abated removal. Plus you'll need to provide a tooth on the surface for the next coating of your choice, in addition to any repairs or fairing necessary (might as well, since you're down to the hull)

Epoxy in the 70's is just like today, same stuff, same chemistry very compatible. Some of the proprietary mixtures have changes slightly to increase or decrease the physical qualities of the epoxy, but this will not effect your needs. Older epoxy can become brittle, especially if much exposure to UV has been permitted (thin or worn out paint, scratches, etc.) Any areas of suspect should be ground back to the reinforcement and recoated. Damaged areas (delamination, dings, etc.) of course should be repaired.

Good Luck . . .

 

If you can blow it off with a power washer, I'd say the area is suspect at the very least in the first place.

 

Might as well get out the sanders & go to work on this project. The liquid removers might help (if proper ones are used) but the secret will be in the elbow grease and scrapers and sanders. Good luck....Skiffman

 

A sandblaster is probably not an option anyway... cleanup would be a major issue. I guess I'm stuck with a power sander and chemicals in the hard-to-reach areas...

Thanks for all your comments. I'm sure I'll be back here if I decide to go ahead.

Regards
Dave