BYYB Forums

Hi all,

I recently purchased a Bolger Micro that I'm going to do some restoration work on. The boat uses the WEST technique of epoxy coated plywood for construction. One thing I need to do is get the badly peeling marine bottom paint off. Based upon tests done by Practical Sailor where they looked at various chemical strippers (see this link : http://www.franmar.com/practical.html), I'm very interested in Franmar's Soy Strip. The product claims that it will remove all sorts of paints including marine paints and epoxy paints. I want to use a stripper to try to reduce the complications of dealing with the toxic bottom paint.

Obviously everything about this product sounds great, but I'm afraid that it might damage the epoxy beneath the paint. Querying Franmar reveals that it shouldn't harm epoxy unless they're 40% solids or less. It appears that System 3 and WEST epoxies are 100% solids and so shouldn't be affected. (I have to assume that an epoxy similar to these was used for construction of the boat.) I'm assuming that epoxy paints are low solids and epoxy resins are high solids and so that I should be okay using this stripper.

I've requested a sample from Franmar so that I can test and see if any noticeable damage occurs, but I was wondering if anybody had used this or any of the other strippers in the Practical Sailor tests on a plywood and epoxy boat.

My plan after stripping is to do some fiberglass repair along the chines and then paint with Zinsser B-I-N Shellac Primer followed by a Patio/Deck paint for a topcoat. I know that there are lots of opinions on painting boats (I've read lots of them here), but I liked this combination in terms of ease of application and safety. Opinions are very much welcome!

Thanks,
- Brice

Brice you may want to test a heat gun and putty knife for removing that stuff with little toxic exposure. That should soften the paint for easy, controlled removal and be much cheaper as well. The epoxy will get a bit soft but will harden right back up after it cools. Try to stay below 150 degrees at the surface.

Brice, most "epoxy" paints aren't really epoxy, but have elements of the epoxy molecule in it so they can call it epoxy. Epoxy, by its nature is a 100% solids product, no vehicle and no catalyst. The chemical reaction between the activator (hardener) and the resin combine, during the mix and form a new, different molecule. There's nothing left over - okay maybe a very small percentage of surface molecules (something like .005%) can't complete the chemical cross link, because of ambient conditions or activator type used. This slight residue is the waxy stuff we call blush and not typical of all epoxy formulations. This of course assumes a complete mix of the resin and activator during the mix.

Epoxy paints typically are a modified alkyd (oil base) unless they are a two part paint system. In fact, if you look close at the small print on the can of "epoxy" paint (single part) it will say alkyd or modified enamel (same thing).

Paint (all of them) need a vehicle (some sort of solvent) to carry the solids (pigmented) onto and into the surface. This vehicle "flashes off" (evaporates) and the remaining goo dries to a semi hard, mostly continuous skin. In many paint formulations the vehicle acts as a catalyst (two part systems can use a true activator, which is a much better way chemically) causing a chemical change in the solids, which cures it.

Heat will not be well received by epoxy coated surfaces (regular epoxy, not paint), in a stripping process. When you get the paint hot enough to blister (the point you take a knife to it) you'll weaken the epoxy enough to damage it from putty knife action or get it too hot and begin to break down the stickumness of the epoxy to the plywood below.

Most retail paint strippers will work on epoxy coated surfaces, but check the label. Most strippers will blister polyester badly (Bondo is polyester), again unless the label says "safe for fiberglass", which is a special mixture of stripper. They can also play havoc with fillers and bungs. It's usually better to get it off the surface too soon and have to do another application, then to wait too long and have lots of surface damage or dried on stripper, that needs more stripper to remove cleanly.

The best method is to ask West System about specific stripper brands that work with their products. They've tested them and will have recommendations. I always test an out of sight area when using a new stripper and try not to get too greedy. I can always apply more, or sand away the last little bits of paint that didn't get stripped.