First post on swaylocks. I’m finishing up my first board right now, 5’6" X22" summer groveler. Been doing quite a bit of reading on the glassing, Watched the JC videos, seached the forum a fair bit.
Here is my plan:
UV Cure gloss and sanding coats
Possible 2nd sanding coat if I make any mistakes on the first. Probably skip the gloss coat.
I originally intended to buy a quart of Lam resin and a quart of sanding resin, but many posts here seem to suggest its better to make your sanding resin from LAM resin.
If I do that, it is a little unclear what the most accepted additive profile would be for the sanding resin. Styrene alone, or surfacing agent (which is styrene plus wax?) or some combination of the two.
I dont totally know the difference or the best approach. Advice on which agent, and how much of each to add would be really, really appreaciated. Its getting down to crunch time!
hey dude, glassed a few boards myself with UV resin, good stuff.
making sanding resin is simple, just add a few squirts of surfacing agent to lam resin, stir it around a little bit and thats it.
make sure to look in the bottle and make sure its clear before you add it to the lam resin, if it isnt clear just fill your sink with warm water and let the bottle sit in there for a few minutes and it will clear up.
Hi S2DM, wax in styrene is what you’re looking for. Styrene alone (known as “styrene monomer”) is used to make resin more flowing (for gloss resin, for instance). Here is what wax in styrene will do:
When you use lam resin without additive, it will always cure “sticky”. This is because of dampness in the air that will prevent the top layer of resin to fully cure. This is good as long as you add another layer of glass or resin over it, because it will provide a strong “grip” with the next layer. Now, if you need to sand, that’s another story, the sticky resin will clog up your sandpaper. So, for hot-coats or gloss coats (both needing to be sanded), add wax in styrene to your lam resin: wax is diluted in styrene (which is a solvent) but as the resin starts its polymerisation, wax (lighter than resin) will rise to the surface and make a protective film from air dampness. This will allow resin to fully cure, making it easily sandable.
do double hotcoats. one to sand everything flat and to open up any air bubbles. Then second as a finish coat. Helps seal up any weave from the first sand.
A general old glass shop rule for surfacing agent is that you add twice as much to your resin as you would catalyst. So 10 cc’s of catalyst would mean 20 cc’s of surfacing agent. If you’re mixing up a pint of lam resin then throw in 30 cc’s of surfacing agent. Since you’re using UV, you should add 5-10 cc’s more since the UV kicks so quickly and very hot. Most people will tell you to “flash” the hot coat which works okay. Another way to do it is to do your hot coat, let the wax rise to the top and then take it into the sun to kick. Boom, you’re done. Styrene is good for thinning out the resin or for brushing on laps to help them lay flat. Good luck!
Not quite accurate. Dampness isn’t the issue. Polyester resin is known as an “air inhibited” resin. Unless a barrier is formed while curing the resin will remain tacky. Surfacing agent (wax diluted in styrene) forms a barrier when it rises to the surface during the cure. It’s direct exposure to air that’s the issue. You could glass a board in a 0% humidity environment, and without surfacing agent it would stay sticky because of the exposure to air/oxygen.
* All measurements are approximations; one must take into account all variables when mixing the resin i.e. temperature, experience, measuring accuracy.
For hot coat (sanding coat) add approximately 25% more catalyst. Always mix the chemicals thoroughly.
Temperature is one of the most important variables when mixing the catalyst with resin. The warmer the conditions are, the faster the resin will go off (gel) and vice-versa. Therefore, make the appropriate adjustments of catalyst according to the temperature of the environment you’re working in.
Thanks all for the replies. For some reason, I had notifications turned off and didnt get updates that there had been posts. Board came out great and I did the few squirts of surfacing agent bit. A guy had previously sold me straight styrene and Id gotten a little unclear on the differences.
