Very nice update on the site Mike, muy bueno! I’ve looked at the archives but was unable to find some info. I know it has been mentioned briefly in the past, but I can’t find it.
Anyway, I’m making a twin fin with homemade plywood fins. I need to find out what is the best way to prime the fins when glassing. In other words, what is the easiest/best way to ensure that the wood won’t suck up too much resin when setting the fins, leaving me with dry spots in my fin lamination? Is there a way to pre coat the fins (with out creating a mess/hassle) when setting the cant, etc.? Or do I just have to baby sit the fin lamination before it kicks?
Back in the sixties we used to put ply fins on fish shapes.Heres how it went:Tack the fin on with a bit of lam resin holding it in place with tape.(you can also use 5minute epoxy)…When it dries pull the tape and prime with lam resin using a small brush.Let it dry before going any further.By priming the fin blanks you accomplish 2 things…no dry spots…and the tacky lam resin helps hold the glass on the fin while wetting it out.We saturated the fin rope in a seperate cup so it would get totally clear and then catylized it.We also added a small rope bead around the fin at this time but you had to work it with your fingers and keep an eye on it.We hotcoated the fin and the bottom of the board last.(note…we used one layer of 8oz glass on the fin because two layers made it hard to work the bead.)There are other ways but this worked pretty good in a production scenario.
THe easiest way to prime the fins is to apply a “split coat”. Just thin down some resin with stirene, catalize, and apply to fins. Let that dry, and then glass on. Polyester resins don’t really like sticking to wood, and mixing polyester with epoxy is also a bad idea.
Another option is to use uv-curing laminating resin. I’ve done this on quite a few fins, and had no problems with delam in the couple of years since the first ones. Always a good idea to wipe down the wood with acetone first, as it reduces any wood-resin at the surface and increases the strength of the bond.