Stripping a Stripper

Sounds redundantly fun but that's not the kind of stripper I'm dealing with. I'm faced with a strip-built kayak that needs refinishing. The old finish is flaking and peeling with all the look of a poly. I'm more of a wood canvas guy so any advice on getting down to the resin/glass without harming it would be most appreciated. My intentions are to sand the whole hull then start building up coats of spar varnish for a more durable finish than the paper-thin poly coating the boat is now sporting.

 

A couple hours with a random orbit sander and 100-120 grit disks will remove all the varnish or paint from a typical canoe or kayak. Buy a box of disks, because they will plug pretty quickly and they don't cut well when plugged-up. Some marine chemical strippers are specifically made to use on fiberglass and some (like Citristrip) don't seem to soften it much and can be used, though sanding is usually faster. Varnish sanding dust and resin sanding dust (as well as the sanded surfaces) are often slightly different colors, so you may be able to tell when you have removed the varnish and should stop sanding just by eye. Obviously, if you start to see the weave pattern, you have gone a bit deeper than desired and should stop sanding.

When you think you're done, wipe it down with water and look for blotchy spots where the color changes. Even with polyurethane, spots where there is still old varnish are likely to be a bit more yellow than the bare resin will be. What you see when it's wet is pretty much what you'll get in terms of color and evenness when varnished.

Point of order: There ain't no such thing as "poly". It's a meaningless term without its tail end. Also, there are a multitude of grades of polyurethane and some of them are excellent. Like any paint or varnish, the price of a can depends on how much of the content is expensive components (filters, pigments, oils, solids, etc.) and how much is cheap thinner. Some of the toughest and longest lasting clear finishes on earth are polyurethanes. You get what you pay for - surprise, surprise. Spar varnish will also work just fine on a stripper if you would rather use it. Be sure to get one that has a good UV filter in it, because its main job on a strip canoe is to protect the resin from UV damage.

 

The original finish on this kayak wasn't one of the best polyurethanes you refer to - or it was poorly and sparingly applied. I plan to use a high quality spar varnish simply because it's what I'm used to, I know how it behaves and can get predictably good results. If there is a more appropriate finish for applying on top of epoxy/strip construction I'm open for suggestions. My only other experience with epoxy was a CLC pram and they recomended spar varnish to protect the epoxy.

 

Spar varnish will work fine if you want gloss and like the slightly golden tint it gives the wood. I've used Captain's Varnish on strippers before with good results. It rolls and tips well and has good UV blockers. On others, I've used polyurethane and it also held up fine over the years. Lately, I've used a lot of General Finishes "Enduro Pre-Cat Urethane" waterbased conversion varnish on assorted projects like guitars and gunstocks and been quite impressed with the quality of the finish. It's the first water-based varnish I've really liked and with the trend toward low VOC finishes, that sort of thing may be the wave of the future. On this one, for example, I used the Enduro for the sealer on the maple, then mixed with pigment for the red base, mixed with tiny metalflakes for the sparkle layers and then used neat for the clearcoats on top. Within about a week, it's hard enough to be wet-sanded and buffed. I'm certainly not thrilled with the current push to get rid of oil-based paints and varnishes, but figure it's wise to keep reasonably current with the new technology and some of it is pretty impressive.