Mixed, poured and brushed out a finish coat on the bottom of what is essentially a display board, using about a cup and a half of new Fiberglass Hawaii lam resin with what I though was adequate surfacing agent. Brushed it out, all is well though no visible wax rising to the surface. Cleaned the brush, then (few minutes later) dragged the rack and board out into the bright sun. The resin set and I pulled the tape, but no wax on the surface, and the board has an orange peel texture and the resin stayed tacky. WTF?
The brush was the same one I always use for boards, and for nothing else, so I think it’s sufficiently clean. Resin is new, surfacing agent just mixed up with new styrene. FWIW the hot coat did this too. I was able to scuff it by wet sanding.
There are areas along the rail that set just fine, but 90 percent of the bottom is going to need another coat. But why did this happen and how do I prevent it?
Howzit Honolulu, Not enough S.A. when using UV resin for hot coats. You need to double the amount of S.A. if you are going to put a UV resin hot coated board in the sun to kick. When UV catalyst first came out they had instructions for doing hot coats, but now since we can buy the pre-catalyzed resin we don’t get the instructions. I did a couple a few years ago and had the same problem and I don’t like the idea of addmore S.A. to the mix since it thins out the H.C… I still use UV resin for H.C.s but I just use regular catalyst to kick it off then wait about 10-15 minutes after it kicks then put the board in the sun to finish the cure to a hard cure.Aloha,Kokua
Thanks Kokua, I was hoping you’d have nothing better to do on a bright sunny day than sit at the computer! (grin)
Okay, so it looks like the resin was too thick (I did not thin it with styrene since I wasn’t concerned about weight). I guess too the thick resin inhibited the wax from rising to the surface to cure. So, for a thick coat, more SA, which will thin the resin as well.
Shoot, Town came up overnight (small sets at Castle’s, even) and I gotta get this done. Oh well, anything for money.
Sounds like the surfacing agent may have been more dilute than you are accustomed to. Perhaps going to an ‘‘out of the can’’, finishing resin, would avoid surprises like you just had. My experiences like that, have been when I had too little,or incomplete mixing of, the catalyst. Always a bummer when stuff like that happens.
Howzit Honolulu,Like I said before use catalyst instead (don’t add extra S.A.) and then put in the sun after the HC kicks off totally. Don’t use styrene either, just surfacing agent, about 1-1 1/2 oz’s S.A.for 16 oz’s lam resin will be quite enough .Aloha,Kokua
Thanks for the comment Bill. I haven’t bought finish resin for years, because all I used it for was finish coats, and thinned with styrene, I didn’t use enough to keep it from going off in the can. Too cheap to buy less than a gallon at a time…the markup on smaller amounts is killer. I’m pushing for inexpensive, so the less I spend, the less is passed on to the customer. My boards are all sufficiently long lasting that I have found no disadvantage to this approach, but there’s always room to learn… as I just did.
More wax in the SA, and more SA (or styrene) in the finish coats. Meantime, 80 grit wet may help.
I’ve had good results using all lam resin, and now that we have UV there’s even less reason to buy either finish resin or catalyst. (Except to use catalyst for pinlines).