I’m working on my 2nd board right now. I laminated the bottom on tuesday after work. I used UV resin with a yellow tint. The tint is not completely opaque (I painted a little bit on the foam and you can see through, plus you can see the stringer), but its taking forever to cure. My last board I only painted on the foam and it cured in minutes in the sun, but this one I have left out in the sun for hours and its still not completely hardened. I guess I should have put a little catalyst in it, but I liked having a lot of time to work with it on my last board.
So my question is: will it ever harden? Do I just need to keep putting it in the sun and be patient? My problem is that I get home from work in the late afternoon so it only gets a few hours of sunlight each day. I’m scared to leave it outside all day while I’m at work. To make things worse I left it out yesterday for a few hours and a bird crapped on it! I was able to get it off, but jeez what bad luck!
Only thing I would say is that if the tint is too opaque then the sun will not fully penetrate the cloth to compltely cure. But as you say if you can see the stringer, then there whould be no problems. I have done several dark tints with UV ccured resin and never had a problem.
Normally in decent sunlight it should cure in minutes! If not then you got problems.
Did you mix the UV catalyst yourself? If you did then this is where your problem most likely lies. Not sure on the ratios but you have to be rather careful to get it exactly right.
I only use pre-mixed UV resin. If you used this then perhaps it was a very old can of resin?
Did you shake it up rather well and strain the resin prior to glassing?
Shoot some answers back and then we’ll take it from there!
Thanks for responding Drew. I did mix it myself. I bought the resin at foamez and the UV catalyst there too. I just mixed the one gallon bag with my one gallon of resin. I used the first 3/4 of the gallon on my first board which I just glassed less than a month ago. The resin is however, about 7 months old and they say to use it in 6 months. I shook the can before I used it each time, so the uv catalyst would be nice and mixed.
Its not like its not hardening at all, just very slowly. I was kind of thinking that maybe its just because of the tint, so it works slower, but what you said is starting to worry me. I even did some test pieces and they seemed to harden just fine. I can’t think of what I might have done wrong…
When i glass with UV resin, it kicks in minutes once exposed to the sun, tinted or not. One day last year, it was hot, like low 90’s but absolutely no humidity, the board cured in about 30 seconds. Full cure. It was scary.
But i am a bit puzzled as to why you are having the problems that you are having. If the test pieces are the same resin with the same amount of tint then your board should have cured in the same manner?
I ponder.
I am now at a loss.
Sounds like you did everything right! The test pieces are what throw me. If those cured, then I am at a loss for as to the curign problems ffor the board.
Let me ask you this…is the surface of the board still tacky? If you press your finger on the glass does it stick a little?
What kind of tint did you use? Was it specifically for resin?
Humididty isn’t really a problem with UV cured resin, so that is not an issue…
Keep replying and we’ll figure it out soonerr o rlater
Heres a thought, did you wipe down the board w/ alcohol before you applied the resin? (did you put any foreign chemical on the board that could have mixed in w/ the resin?)
Yeah, I used the same resin for the test piece. I bought the pigment at a surf shop in Pismo Beach that I believe gets all of there supplies from Fiberglass Hawaii. I mixed it just by eyeballing it. I put in enough that it looked yellow, but you could still see a little bit of the greenish-blue color of the resin.
The top has mostly dried. I can touch it and its tacky, but its stickyer than my last board was. The rails are still not hard, because they have not gotten as much direct sun exposure. I feel like with enough time it might fully cure, but It just seems strange that its taking so long.
Sorry I forgot to answer that, no, I didn’t use any MEKP. I was going to, but since my test pieces came out okay, I figured I would rather have the extra working time.
Since I mixed it all just by eyeballing it, I am beginning to wonder if maybe it was just too much tint, and its too opaque. Since I don’t have any experience with the tint, I don’t know. But it is definitely not completely opaque. I can definitely see the stringer, and I painted a little design on the foam and it came out really well. ( Side note: I actually painted in yellow and tinted yellow, and I really like the look of it. The places where the paint is, is just a little darker. So its a really subtle design).
uv cure resin uses yellow wavelengths of light to cure… very light yellow tint is ok, and even that can double (or longer) your cure time… anything close to opaque, any color, with uv is a no no… keep it in the sun… maybe put a thin clear plastic film over it (1ml painters tarp?) to protect it…
Yellow tint with UV should cure superfast. either you didn’t mix the UV dust properly , or there was too much tint in the batch. I’ve had UV tint kick with every color in the spectrum, even dark grey. But if you add too much color you slow the resin chain reaction way down, if you do that you need to kick the cat up, if you kick the cat up you get a brittle board…but it should still kick. I’d say just put the board in the garage for a few days, it will kick.
Sometimes resin does wierd shit, and this So Cal weather isn’t helping much. Humidity can screw with the kick times too. Don’t know what to tell you, worst case is you keep on with the build, coat it in hot coat, that’ll teach it!
wait a minute, you said tint, but then you mention opaque? which was it. If it was opaque paste, then the sun can’t do it’s thing…and your stuck with a mushy board for a few weeks. It will cure, but your going to have to wait it out.
It is starting to harden, I put it out in the sun for longer yesterday, but it is still definitely not completely hardened.
Resinhead, I guess I lack experience in the pigment/tint area. Through reading lots of posts, I seemed to get that if the pigment you put in the resin still allows you to see through it, then it will UV cure. The stuff I bought came in a little jar, its like really thick paint. I just spooned in a little at a time and mixed it with the resin, till the color looked yellow enough, but like it would not be completely opaque.
So your saying that it will harden eventually, but it might just take a while? Does that mean I have to put it in the sun everyday for a while, or can I just leave it in the garage for a week or two? I’m going to be gone for a week and a half anyway…
As far as laminating the top, should I just add MEKP this time? What is the least amount I can add so that it will still harden, but leave me plenty of working time? (I’m pretty slow at the whole laminating thing).
You wont have any problem with suncure on the hot coat, just remember to give the hot coat plenty of time let the wax rise, and let the brush stroke smooth out before you walk it out into the sun. walk slow, so the resin doesn’t slab off around the rails.
Just finish up with what you doing,. No problem, just go with the rest of the lamination, or if your done laminating, hot coat it, then set it in the garage while your gone. when you come home it should be ready to sand. I suppose your garage has windows? If no garage windows, put it under a tree in the backyard, or some place where it won’t get direct sunlight, but the UV will bounce to it.
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