Resin and painting post fiberglass canoe repair

I was gifted an old fiberglass canoe. I’m in the process of repairing. I have all the old paint and patches sanded off down to the base layer. Which appears to be a blue powdered type bonding resin. I have no idea what brand or manufacturer built this canoe.
What I’m trying to figure out, is should I paint this powder coat once the holes are patched and filler applied and then apply resin over the paint? Or should I do the opposite and apply resin first then paint?

You cannot resin over paint. You can paint over resin.

Thank you very much.

Would it be worth it to tint the resin as well? Or just do the resin then paint it?

Little reason to tint the resin if you plan to paint over it.

Resin…lets assume you are talking “epoxy resin” . Epoxy reacts to UV and needs protection. It gets sunburnt and looses strength…over time. Hence the paint for UV protection and looks second. Paint is easier than tinting the epoxy. Marine varnish does the protecting too. DON’T use both.

Now you can do “gell coat” to get color, protection and shine but asking the questions you are that isn’t the system for you.

Epoxy sticks real well to a lot of things. It does not stick to dirt, grease, oil, paint or heavy dust. Clean your area to be coated . Denatured alcohol some times sold in hardware stores as “stove fuel” does this well and drays fast.

We typically use marine paint . I typically use “Pettit” Topsides paint. Note it says not for underwater use. Not applicable to canoes unless you will be leaving it at anchor. :grimacing:

I was planning on using the fiberglass resin. Not epoxy resin. As it was much available and cheaper. Plus I needed it for patching the holes.

Painting over that still sins like the best option.

There are three basic varieties of resin that are used in the construction of composite canoes. Any of them might have been used to construct your canoe.

These are polyester, which is what Bondo and many other resins are, which is catalyzed using a small quantity of methylethylketoneperoxidase (MEKP). Polyester is the cheapest but also the weakest resin used in canoe construction. If your boat is an older fiberglass, relatively low-cost canoe, there is a good chance that is was constructed with polyester resin, but it is not a given.

Another type is epoxy which is the strongest resin. With epoxy you mix the resin with a harderner in a fairly precise ratio rather than a catalytic agent. The two create a chemical reaction that results in cured epoxy. While epoxy is strongest, it is also the most expensive. The chemical reaction that occurs with epoxy cannot be speeded up by adding more hardener. In fact, the ratio of hardener to resin needs to be fairly precise or the epoxy might not cure.

Vinyl-ester resin is the third type, sort of a cross between polyester and epoxy in some ways. It too is catalyzed by adding MEKP to the resin and the cure rate can be adjusted to some extent depending on the amount of catalyst added. Vinyl-ester resins are use by most makers of high quality canoes these days for a variety of reasons, chief of which is that they are less expensive than epoxy. But many vinyl-ester resins are less viscous than epoxy so they work better with infusion or vacuum bagging construction methods. And a faster cure time can be achieved which can be important when building whole boats. Vinyl-ester resins have come a long way. They used to be distinctly weaker than epoxy though stronger than polyester. But I have been told that some now rival epoxy in strength.

What’s the difference? Well, polyester resin may not cure properly if applied to a boat constructed with epoxy, and possibly not when applied over vinyl-ester. So before you do anything more I would try to find out what resin was used to construct your boat. If you have already used polyester resin to do some patches and it seems to have cured well you are probably OK using it to apply a cover coat to the entire boat, although it would not be my choice.

I have had good luck using low viscosity “penetrating” epoxies for this purpose such as System Three Clear Coat which goes on and levels much like varnish. A nice thing about epoxy is that is will cure no matter what resin your boat was built with.


Light blue is the color of the old polyester resin hardener from the early days like the 1970s. That is not a good sign. It is relatively weak compared to epoxy resin and also pretty old.

Try to figure out if the fiberglass is still rigid. Does is feel spongy or soft anywhere?
You can always beef up a boat with epoxy resin. It will add some weight, but a lot of strength. You can paint everything when you are done. Good luck.

Overall she’s hard. No soft spots outside the two holes that I patched today with mat and cloth. Filled in the outside with short stain filler.
We have no idea of the age of this canoe.
I removed all the weak or cracked spots. And filled in the holes in the keel with same short fiber filler.

Next I plan on adding fiberglass cloth along the entire keel for a solid structure and seel what I just filled in.

Then resin layer over the entire canoe. Then paint.

Thanks everyone for all the advice. It’s coming along. Great so far. Can’t wait to post final photos

Patched and filler applied.