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I’ve done a lot of things in my life, but, up until this project, I had never done any fiberglass work, and now I feel that I’ve added one more “piece of the puzzle” to my love of prototyping.
My son, Matthew, and I learned how to fiberglass via youtube instructional videos, a few websites explaining it, and just plain ol’ following the directions on the resin container.
I went to DAP Plastics and bought about 3.5 yards of fiberglass cloth (cloth, not strands or just loose fiber–kinda like particle board for fiberglass) and fairly cheap polyester resin. Epoxy is said to be much better in quality, but it is also nearly twice the price, so I opted out and chalked this up to a learning experience.
Firsts Things First: Sand Baby, Sand!
Well, before we started, I tried to plan ahead. First, we Bondo-ed all of the cracks, holes, and seams on the outer hull of the ship, I mean, little tiny boat. Teaching Matthew to work fast and trowel that smelly junk on was fun and a trial at times, but he seemed to finally get the hang of it.
Fiberglass: Plan Ahead
Because I only bought a little more than 3 yards of cloth, I knew we wouldn’t be able to fiberglass the entire inside and outside of the boat, so I opted to do the bottom and the sides (and the bow and stern) of it. We rolled it out and put it into place. Having read ahead, I knew that it would be foolhardy to roll it all out and try to get it all covered effectively in resin in the pot-life of the resin.
[BTW, polyester resin is mixed as a two-part chemical reaction. Once it “becomes” polyester resin via mixing, the time starts to tick, and you’ve got to move your ass and get it done before it sets–you’ll know when it sets because it will stat to turn from a liquid to a Jello-like consistency, and then it’s all over. Right after that it turns hard and it’s done.]
Fiberglass: Don’t Be Afraid to Make Mistakes!
I’m really not too much of a big idiot, but I sometimes make mistakes. The great thing about it nowadays, is that I don’t take it nearly so hard, and I always expect a few mistakes for each new project I take on. Well, this time, I made a HUGE mistake. The directions for mixing the polyester resin called for a certain amount of catalyst to be added to so many ounces of the resin and, since I must have lost a bunch of brain cells sniffing Bondo earlier, I didn’t understand it completely. So, Matthew and I began spreading out our resin mixture (with not enough catalyst added) onto the fiberglass cloth spread out over the bottom of the boat.
About 45 minutes into it, I figured it should be gelling (or setting), but nothing was happening–it was as wet (and blue) as when I poured it. So, after reading that it supposed to turn clear (with a blackish tint) when enough catalyst is added, I realized that I had made a terrible mistake, and possibly wasted a bunch of expensive materials.
But, we had put in too much work for me to scrap it, so I figured I would go back out, mix a little bit of resin with a large amount of catalyst and then quickly add that to the stuff already on the boat and maybe it would all kind of mix wet-on-wet, like one of my watercolor paintings. Obviously, this is something I would never do again, but I had to salvage it, right?
Well, I tried it and guess what? It worked. The catalyst immediately turned the stuff on the boat a blackish clear, instead of a blue, and the smell changed a little bit. Within about 15 minutes, it started to harden, and I could check it by the material left in the mixing pot/cup–that is usually a way to check the set of a chemically-reactant material–hence the term “pot-life.”
So, the next section of fiberglass worked a LOT better once I mixed it correctly with the catalyst.
Here’s a little tip when applying fiberglass: We found that the squeegees they sell work a HECKUVA lot better than paint brushes for moving the resin around on the cloth. You’ve gt to work it into the cloth–the fiberglass will turn from white fibers (like cheesecloth) to clear and see through, You can even see the wood grain through it.
Once it is dry and hard, you can add more layers of cloth and resin. Cool thing about polyester resin is that, while it is “green” (or, fresh and not fully cured), you can add layers of more cloth and resin without having to sand each layer. Despite this, Matthew and I sanded the hard and rough spots, and added a second layer in spots that looked like they might get more action in the water from rocks and gravel, etc, like the keel and the corners of the boat.
Once we let it sit over night, we added a couple coats of exterior white house paint to add one more protective “skin” to the boat.
> The Maiden Voyage of our Homemade Plywood and Fiberglass Boat