Boat Building Forum

Find advice on all aspects of building your own kayak, canoe or any lightweight boats

Re: more questions
By:Paul G. Jacobson
Date: 5/6/2000, 9:58 am
In Response To: more questions (Tom Kurth)

: Coupla questions I forgot: What kind of paint can you use over epoxy and what
: kind of prep do you need to do? Thanks, Tom

Working backwards: for prep -- a light sanding to remove the gloss from the resin and also any reidue that might have migrated to the surface. Depending on the chemistry of the resin that might be wax, styrene plastic, amine blush or something else. Whatever, it all comes off with slight effort with a fine grit sandpaper.

Some people like to use very fine grades of sandpaper on the resin, but I think that the thicker the final coats of paint or varnish, the less necessary such extremes of sanding becomes. If you are putting on 5 coats of varnish, I'd save the 300 grit sandpaper or finer for the 4th coat of varnish. Any "scratches' left by using 80 or 100 grit sandpaper on the epoxy would have been filled in by the first three coats of varnish, and the finer sanding done to them. On the other hand, if you just plan to put on a single coat of varnish for the UV protection, then do all your fine-grit sanding on the resin, as that single coat won't fill very much.

Oil based enamels, and polyurethane coatings seem to work well on epoxy, with polyurethanes being the majority of the paints I've seen on the shelves at the boating supply shop. There are two part epoxy-based paints on the market -- primarily seen in the local hardware stores for refinishing bathtubs, or sealing concrete floors. Epoxy based paints should be ideal for coating epoxy. The colors sold in the hardware stores tend to be either white (for tubs) or tans and grays (for floors), which seems to be a bit too "blah" for my taste, but if you are building a cedar-strip battleship, then gray would be ideal. Two part polyurethanes have been reported on, and they seem to be hard as a rock, but also difficult to apply and require above-average care in application -- don't breathe the fumes. A few minutes looking at laels in a marine supply shop, or going through the catalog of such a place will give you an idea of the variety of paints that are on the market. Many of the offerings are "hull" paints that contain materials (like a high copper content) that will either repel barnacles, or "ablate" (flake off) and fall away from the boat, taking any attached barnacles with them. These features are of greater use on boats that spend all their time in ocean water. Small boats that are generally removed from the water between uses, and stored dry, have no need for such expensive features, so paints designated as "topside" paints are generally used. Will a paint containing teflon make your hull more slippery so it can go faster? Who knows. If you think it will help, then go for it. Personally, I think a bigger paddle would do more for speed than a paint job.

Defender has some data in their online catalog at www.defenderus.com, and you can probably find lots of links to marine paints with any search engine. Pettit is one brand I've used, and I think they have a web site. West Marine also sells their own line of marine paints and enamels. If you see other brands listed in a supplier's catalog, try searching on the brand name for a manufacturer's website. Such sites usually have a wealth of information and can assist you in finding the finish that will work best for yourclimate and boating conditions.

Hope this helps.

Paul G. Jacobson

Messages In This Thread

more questions
Tom Kurth -- 5/5/2000, 10:50 pm
Re: more questions
Paul G. Jacobson -- 5/6/2000, 9:58 am