Looked through the archives but couldn’t get a concrete answer, so I figure I’ll ask. I just finished hotcoating a board, ~10th board I’ve glassed, but first time using UV resin. The first side ended up somewhat sticky (not as sticky as lam would’ve been but too gummy to sand), and I figured it would just cure with more time or that I hadn’t given the surfacing agent enough time to rise before exposing it to UV. Second side I gave the surfacing agent more time to rise (~5 min between last brushstroke and UV exposure), but this turned out sticky as well, even after ~2hrs in the sun (full sun ~75-80 degrees).
My question is twofold
Anyone know why this happened so that I can avoid it in the furture?
What can I do to fix it? Sand through the gum and lose my sanity? Re-hotcoat (looked like it had the shiny waxy hotcoat look so I don’t think a second hotcoat would go on good)? Wait on it?
First-- You don’t let the Wax rise before you expose the board to UV. You brush on the hot coat and then immediately exspose the board to UV. In bright sunlight a count to 10 or 15 seconds is enough. Then take the board back inside, set it on a rack and let the Wax rise. You will see the hotcoat change to a “oil on water” type lustre. After a few minutes(doesn’t really matter how long) inside, set the board back outside and leave it until hard. Follow these steps and it works every time. Your problem is that you are doing the process a$$ backwards. Exspose it to UV first then let the wax rise. Secondly— The only cure is another proper hotcoat, both sides.
Mako makes a good point. If the resin sat for a while you should have stirred it well before using. I would have guessed you over brushed the resin but it seems you did not, judging by what you’ve said. One element not mentioned is the ambient temp when you did the hot coat. Could be a factor.
What Lowel (Mcding) said. Here in SoCal we do 5 - 10 seconds and then back inside where there is no ambient light and wait for the wax to rise. Never had a problem and we always use fresh resin. Also, you could cover the board in wax paper (tightly) and let sit for 24 hrs. or more. The wax seals the resin from oxygen and lets the reaction finish off, then you can peel and sand like normal. I always put a couple of drops of cat in the UV hot coat just to be sure. Just my 2c…
Temps don’t have much if any effect on UV. It can be 30 degrees, but if the sun’s out, it will kick. Or better yet if you can build a UV box, it’s all good.
Hello; you did it right. Problem seems that the resin used did not have enough wax. With or without UV powder, resin with not enough wax turns always that way.
I mean wax not styrene so if the styrene monomere that you have for any reason do not have enough wax, if you thinking that adding more styrene could be a solution, will not
What I said in the beginning. You don’t brush it on and then wait. You’ve got to walk it out in UV to set the chemical reaction in motion. To the count of ten and then back inside until the wax rises. You stated plainly what you did. You’ve got the process backwards. This is the only thing you are doing wrong. These other guys are sending you down a rabbit hole. Do it right and you will have no problema.
You stated; " I hadn’t given the surfacing agent enough time to rise before exposing it to UV." This is backwards. Expose it to UV and then back inside to let the wax rise. All this other stuff you are hearing here is theory or wild speculation. Gee!
I’ve never taken a hotcoat outside and then back inside. I’ve always waited 5 minutes after brushing it out. Never had a problem. To each his own. That’s what has always worked for me.
Depends on whether or not there is any UV light getting “inside”. Might even depend on what bulbs or light source you use. Letting it sit inside is a gamble. Plenty of info confirming this on YouTube, SolarRez etc. What the hell? Do it any way you want. I don’t have to sand it, so makes no diff to me.
Surf Source YouTube video on SolarRez. Which is nothing more than Silmar 249 with UV powder. Since we’re talking decades; I first bought UV Polyester from Fiberglass Hawaii in 1998. Bought in Fives premixed, just like they sell it these days. Was told to do it the way I described in this thread and other threads on this site in years past. So by my calculation I’ve been using the $#!t for about 23 years. Of all the manufacturers, backyarders and one off board builders I have met, I have never heard one of them lay off a hotcoat and then leave it in the shade without first exposing it to UV for ten seconds. When I lived in Pismo Beach, there were lots of mid morning overcast days. Never had a problem as long as there was SOME UV. Clyde Beatty used UV in Santa Barbara at his factory and did the exact same way I do. I don’t know the circumstance you are working with, but I’ll pass on trying it your way. I’ll go with the method surfteach and most people use. I always smile when guys say they’ve been doing something for a decade or years.
Whatever works for you. For what its worth you can see the wax start rising to the top as soon as you finish brushing it out.
The only context I’m aware of where best practice is to go in and out of the sun is when firing off your resin in intense sunlight. In this context it is it is done so as to slow the curing process.
Strangely, I went to surfsourse.net and the only video I found that made any mention of this topic said to do it the way I describe. If you have a specific link from surfsource or elsewhere you’d like to share please copy and paste it into a post. I’m open to other methods but without a link I’m starting to think you’re full of hot air. I’m happy to be wrong mind you but would like to see some specific proof of claim.
Like I said, if you have a specific link you’d like to share with the group simply right click on your link and select “Copy” then come to your reply on this webside and press “Ctrl V” to paste the link into your post.
No you’re the expert buddy. You’re the one who felt the need to act like you’re the all knowing one and had to tell experienced builders that they don’t know what the F they are talking about. Post me a link to anything on the web that tells you not to wait to let the wax rise to the top and that best practice is to as you said “brush on the hot coat and then immediately exspose the board to UV”. You’re the one who made the claim, and I quote: “Plenty of info confirming this on YouTube, SolarRez etc”. Put up or shut up. I’ll wait patiently.