I’ve looked through the archives on ways to prevent it from happening, but nothing is working for me.
I’ve tried:
stirring the batch
letting the board w/ hot coat sit for 5 mins before initially putting it out in the sun
exposing it for 30 secs, bringing it back into the shade for 5 mins, then back into the sun for the final cure
None of that seemed to help. The hot coat is always a bit sticky and has a scaly, textured look to it. Yesterday I hand sanded an entire board because the paper clogged up within seconds when using the power sander.
I’m using fiberglass hawaii’s premixed poly sanding resin, and the temperature outside is probably in the mid 60s.
Could the colder weather be causing it? I also tend to leave my hot coats fairly thin… not sure if that would affect things or not. What confuses me is that I’ve done a number of successful hot coats before in the same conditions using the same materials. I can’t figure out what variable has changed.
Any advice would be hugely appreciated by my shoulders… hand sanding an entire board from rough to fine is tough work!
add some catalyst (MEKP). Thin hot coats is part of the problem, cold temps don’t help either. It’s called a hot coat because its supposed to be catalyzed a lot (relatively speaking) so you’re not going to be hurting anything by adding MEKP.
whipe it down with acetone…should sand normal after that…im almost thinking wax additive is possibly no use…this is very valuble information…i took me a while to figure it out…try it .
Listen to Keith and J.Troy. I’ve had the same problem until I started adding cat. to my sun cure hotcoat resin. I also found if I stick with the power sander and frequent gum-ups I get through the outer gum layer and they sanded normal after that. Mike
I could also add that since I started mixing my own hotcoat resin from lam resin I have not had any gumming problems, too. I think I add 10cc of surfacing agent to every 16 oz of resin. Mike
I bet the biggest problem areas are around the rails on the top? probably not an issue on the bottom?
I’m jumping into this late, but I’ve found out that using UV resin for the hotcoat is just another possibility to screw up. I only use UV resin on the lamination, all hotcoats are either UV plus cat, or just cat / standard resin. When I use just UV hotcoat all sorts of weird things happen when you try to move a wet board into the sun. First off, lots of times you get the brain crackle pattern when the wax separates and slabs off the board from moving it,(usually on the rails) resulting in those tacky spots you talk about. Secondly if you get a little wind blowing over the hotcoat, besides from getting bugs & dog hairs you get this tacky orange pealed surface that you have to sand off.
It seems that your getting a good kick, but your wax is leaving the board and winding up on your tape line, or the floor. Once you hotcoat, don’t move the board. Best to just use UV with cat. Do the board let it kick to gel state, pull tape, walk it outside and bake it to a hard crispy shell.
sorry this is so late, i had the exact same problem a while back, started using cat. that worked. however, i became impatient and started using no cat. ive found that if i let the hotcoat sit approx 10-15 min the wax comes to the surfaCE UNIFORMLY and havent had a problem since. 5 min was not long enough.
You say you have had good results with the same materials in the past. Were those batches from the same can of resin? If you didn’t mix it up really good on the first batch, it’s possible that most of the surfacing agent got poured off with the first batch. A few ounces of surfacing agent is cheaper than a new can of resin if you can find some. I’d try adding some more surfacing agent. Is there an expiration date on the label? Old resin can also be a problem.
The wax is not rising.Resinhead and John nailed it.If you buy premix resin in a can you need to mix it well.Just giving the can a shake will not do it.Dump the whole deal out in a bucket and stir well.Look to see if the wax has settled to the bottom of the original can.If you see wax on the bottom put some resin in and loosen it with a dowel.Surfacing agent is nothing but wax+styrene.Styrene will float and the wax will sink.When using UV it’s best to add catylist like a normal hotcoat and let it jell before taking it into the sun.If you go the total UV route 5 minutes is not enough…more like 20 is needed but you are asking for trouble.The rails may be sticky. RB
I found this old thread doing a search when I was trying to solve a ‘tacky’ hotcoat issue (i.e. looking for reasons / solutions, etc.) … anyway, I found another thread on here at the time, in which there was a post (from Herb I think if memory serves correct), that mentioned to use wax paper on the board to solve the ‘tacky’ issue … but, for the life of me, I can not find THAT thread or post again !
Anyway, it seems to have worked … I have a couple of posts (with pics) of the problem and solution on my website … might help someone else with the same issue.
Ten to twenty seconds outside on a hazy Coastal day. Then back inside for ten or fifteen min. before you take it back outside to finish it up nice and hard, You can see the haziness of the wax rising while it’s sitting inside. And no light onshore breezes. UV hotcoats don’t like 'em. Never Gloss with UV. If a can of UV sits around for awhile it will settle. With UV it’s not the wax you gotta worry about; It’s the UV powder. . All your UV powder will be on the bottom of the can.