Great Article on Fiberglass Repair

Below is a link to an article I found on fiberglass canoe repair. I found it to be very helpful and have managed to fix up a canoe that I thought would never float again. Especially interesting/useful was the single sided patch (using a popsicle stick).

Thought I would post this here as it might help somebody else out.

Sorry, Andy, there are some good ideas
but also some serious errors in their advice. For example, those of us who repair whitewater boats again and again do NOT put the smallest patch on first. The largest patch must go on first, and so on down to the smallest.

Kevlar cannot be sanded? Yes it can. It doesn’t sand well, but it sands well enough for practical purposes.

Mat? They don’t mention the fact that glass mat has a coating such that epoxy will not adhere well, and one will have to use inferior polyester resin.

I’ve had to wade through lots of good and bad advice over 40+ years of boat repairs. What you provided is worth reading, but only if one knows enough to sort out good advice from bad.

There are several other errors, too

– Last Updated: Apr-17-11 10:05 AM EST –

I agree with everything you've said and here are a few more corrections.

- Fiberglass cloth is not typically composed of "twisted strands", but unidirectional fiber bundles that are woven into cloth.

- S-glass is not a "patterned material", it's chemically different from E-glass - which is what makes it stronger - and it can be woven into the same types of fabrics as E-glass.

- Gelcoat is not "micro thin", it's much thicker than paint and can be built up to any thickness. On some kayaks, this is taken to an extreme, particularly along the keel. This may be true of some canoes as well.

- Gelcoat is not difficult to apply in typical repair situations and scratch repairs are downright easy. Color matching can be difficult, but that's true with any repair material.

- Colloidal silica does not "sand easily", at least not compared to un-thickened resins and other types of fillers. It's actually one of the more difficult fillers to sand, because it essentially IS sand, just micro-fine. It's actually used both as an abrasive agent and in anti-abrasion compounds.

- Epoxy thinner? Acetone is the standard, but alcohols (isopropyl, ethyl, or "denatured") work well and are less noxious. Denature alcohol is my preferred solvent for cleaning uncured epoxy (or epoxy components) from tools and surfaces. I've never thinned epoxy for doing fiberglass repairs, but I've often thickened it, so epoxy thinners are large a moot point.

- Paste wax and pumice??? You can buy "Rubbing Compound" and "Polishing Compound" at almost any auto supply store, so why would you bother with a home brew?

- In case anyone is wondering what "episizetm biaxial tape" is, "Episize" is a trademark (tm) of West Systems for their fiberglass materials.

What happened to all the other posts?

Perhaps the OP pulled them.

It’s a moderated forum

Yes, but I can pull any connected string
out of a thread by deleting my own post. All following it will go. So Andy might have deleted his post expressing his dismay over the (limited) criticisms Bnystrom and I had made, and when he deleted his post, then my and other comments on his post would disappear.

Based on past experience, I would not have expected Brent to delete that part of the thread, but perhaps worse posts appeared later.

My position is that folks can learn some things from the linked article Andy supplied. I just think a few of the things they would learn would not be strictly true.