I’m in the middle of glassing a pair of wooden keel fins. This is my first time using fiber glass & resin. I am trying to follow the process layed out by Bert Burger in his famous thread from a few years ago ( http://www.swaylocks.com/forum/gforum.cgi?post=161667 ).
I have already put one side of glass down on my fins and am waiting for them to set. BTW, I’m using poly resin. Anyhow… I just added my hot coat layer like Bert described in #17 below.
Quote:
16;work out the bubbles with your finger and brush and smoothe glass till your satisfied…
17; hotcoat and go to lunch…
18; a few hours later peel everything off the table…
Back in Black
Here’s my question. Why hot coat now? I know this is a simple question, but I’m totally ignorant. The fins will be hot coated again after being glassed to the board, what is the point in adding the hot coat at this stage?
Here is a picture of where I am at in the process right now.
I think Bert’s method was developed with a degree of efficiency in mind. By hot coating the first side, you save having to flip and flip again. You can also hot coat as soon as the laminating resin gels. As I recall, he had quite a large panel of fins going all at the same time. Combine all factors = saved time.
For a “one off” type of project like yours, I wouldn’t think it would matter too much either way.
Hot coating may seem unnecessary prior to glassing on to board but a smooth surface is a good place to start. It’s not always easy to hotcoat raw fiberglass and get a good fill with a vertical orientation. You should scuff both sides of each fin before glassing on to board.
By the way, those fins are looking great! Sorry again for flaking out.
Sorry - just saw this thread. Posted you a tip on your other thread as well.
To answer your question, it’s easier get a good even hot coat when the fins are flat as opposed to when they are glassed on your board and are upright. The process I follow is slightly different to Burts as per the following, but again it’s just personal preference (Dunno why, but I like to Lam both sides first then hotcoat… not sure why, just habit?)
Lam side 1
Flip
Sand side 2 (just cleaning up drips and roughing up glass on side 2 for better bond)
Lam side 2
Hotcoat Side 2
Flip
Hotcoat Side 1
At that point, I then cut the fins out and clean them up with the sanding process.
I like to have the fins sanded and ready to roll before glassing them onto the board.
I just finished the “Bert Fin Process”, and when I first read it I wondered why he bothered to hotcoat as well. After laminating though it was pretty obvious that significant refoiling was going to be necessary on the leading and trailing edges to get back to the orignial shape. Sanding the lam resin doesn’t work so well so you really need to hotcoat first.
Another reason to hotcoat is that lam resin will eventually get hard so if you don’t glass them on a board for a while you’d need to sand them and it’s hard to sand a laminated weave surface without grinding away half of the top layer of cloth.
Howzit fishexp. The trick to getting a nice hot coat of fins already glassed on the board is to start your hot coat with the fins. This lets the resin drain off the sides and by the time you get to them doing the rest of the bottom you hit the drips that ran down the fins. This is also how to do the fins when glossing. Aloha,Kokua
Laminating resin dries with a tacky surface, if you handle the fin you’ll get finger prints stuck to the surface, and also any dust you may stir up. Sanding resin dries hard, so by appling a coat of sanding resin over the laminating resin allows you to handle the fin without causing any surface defects, and allows the resin to flow out better…(as mentioned before)…
I have another question. Is it possible to just skip the glassing until the end when the fins are to be attached to the board? Does anyone every do it that way? It just seems like this is a lot of extra work. Why not just add a few extra football patches?
Note: I’m not trying to take short cuts. If its what needs to be done, then I’ll do it. I just want to learn to do it the most efficient way possible.
Would you do 4x6oz on each side that way (unglassed wood fin)? If so you’d end up with some pretty thick patches on the bottom of your board. I guess you could just use 2x6oz patches with the bare wood fin but I like the strength that the extra layers of fiberglass provide on the fin.
I’ll either use 4 layers of 6 oz., or 1 layer of 10 oz. with 2 layers of 6 oz. over it on my box fins, I’ve yet to do a glass-on, so I really couldn’t comment on that.
Howzit Meatball, That’s why you should wear gloves and acetone cleans the finger prints off. When you make a fin plate you always lay down wax paper before laying up any glass and always hot coat after the last resin layer. I was referring to after the fins are glassed on the board before hot coating the bottom. Started making and foiling fins when I was about 14 years old, that was 43 years ago, done way more than I can remember.Aloha,Kokua
Thanks for the step-by-step instructions Bill!!! Great pictures too.
Thanks to everyone for their help. It is great to have a place like Swaylock’s where you can ask rookie questions, and be given expert advice.
Here’s an update to my project:
After seeing hundreds of bubbles that somehow slipped under the lam; I stripped off the fiberglass from my fins, and cleaned the resin off with Acetone (See images in The Balsa Fish Project thread). It was shocking how easy it was to pull the lam. coat off of the fins.
I’m going to try again soon. I’m not sure how soon though. I’m going to Baja this weekend. I’ll keep posting the results.
Howzit swied, Those bubbles are most likely caused from not milking the glass rope, which is what Bill is doing in his instructions. It's called milking because you use the same technique that a dairy worker uses to milk a cow. Another step is once you have the rope and glass on the fins use your finger and run it along the area at the base of the fin to get rid of any air left. Just be careful not to spread the rope when doing this.Aloha,Kokua
Bill, is roving just a whole bunch of individual strands of glass?? If so, could you just peel off 10 or so strands and use them as your rovings??. Excuse my noobiness.
So I think I just found the answer to my question at the top of the page, But ill put it out there to be totally clear.
Im glassing some wooden fins (that i will glass on a HWS). Ive only done patch work Glassing before. The question is, what do I put under the fins / on the board im using as a table to prevent glassing the fins to the table. . I glassed 3 fins and as i started i had an oh crap moment when i somehow forgot to put a barrier of some sort down.
Well with a little elbow grease 2 fins peeled off fine, when very tacky. Had I waited another 10 mins all would have been lost.I lamed the other side and they are good to go. Last fin had gotten way too hard and snapped in half when I tried to pry it off.
I’d rather not make this mistake again. Wax paper under this fins? I saw another thread that had brushed on wax? Release agent? Should I just putty knife them off a little earlier?