It was very hot the other day- over 35 degrees centigrade.
I am well aware of the potential gassing problem when laminating so I waited for the temperature to start falling, as is the done thing.
However after cotcoating There are lots of little areas where it looks like the resin has been sucked into the blank like what are reverse pinholes, so during a normal sand I would be left with loads of shineys. I am going to have to sand and re-hotcoat. …
Is the temperature the likely cause? Im pretty good at keeping the blanks clean after shaping, and I like to glass right after shaping to avoid contamination, I never touch boards with my bare hands before or during the lamination process .
Take a nearly empty plastic milk or orange juice jug out of the refrigerator. Take off the top and let it warm to room temperature (6 hours). Replace the top securely and put the jug back into the refrigerator. Let it cool back down. Look what happens to that plastic jug.
I have done the same with plastic gasoline containers. Leave it out in the hot summer sun with the top off. Replace the top in the heat and seal the the container. Put the sealed container back in the cool shed overnight. Look at the container first thing in the morning cool.
Seal a container with hot gas (air) in it. When you cool the gas it contracts and the pressure drops inside the container. The temperature differential between the time you sealed it and when hits minimum temperature determines how much negative pressure develops.
I always laminate and hotcoat in falling temperatures, but in future I’ll try not to glass on such a hot day.
Its no big deal, it just means that I will lose the afternoon with the extra time the board will take, but its always good to know for future to avoid the potential problem again
I’m no expert at glassing eps so take it with a grain of salt… I drill a couple of holes as I’m glassing to allow for some equalization of pressure. The holes don’t have to be very big - just punch one or more in the bottom lamination (where fin box(es) go) as you laminate the deck. Punch another for your leash plug as you fill coat. It’s maybe a good idea to make sure your holes communicate to either side of the stringer in a stringered blank.
You’ll still face possible issues when you finally install the last plug or box but it’s easier than dealing with pinholes (or depressions?) all over one side.
Maybe move to XPS if you can, it’s more like PU foam to shape, doesn’t suck, more rigid and you’ll look cooler with a blue blank. XPS in Australia comes from the UAE , go figure ?
the pinholes could be caused by air in the lamination rather than the blank gassing. Seal the decks in a cabosil/ epoxy mix, then let it sit for 30mins or so to allow for the air to rise out of the blank and there should be no problem with gassing unless its a bad blank. If it does gas you can just pin prick the bottom like John suggested.
I would have gone with the high temp explanation until you said it was Poly/PU. I would therefore say your Poly blank “out gassed”. A problem lately with a particular US blank manufacturer. I’m not guessing.
What McDing said is true. A few months back, US Blanks had a gassing problem, They took back blanks and re-imbursed many builders. The most effected were the Gloss and polished LB guys.
Some of us lucked out and and nearly missed the bad ones.
…I had this gassing problem with Surfblanks and Arctic too. The boards finished glassed without bubbles, then after couple of days in the sanding room with high temp, killed that nice work with those tiny bubbles…
I put it under direct sunlight to cure UVresin, and I had the same problem. 1 minute no more then the bubbles started to appear.
-Possibly these other things (like aniline) that they put in the mix to try to have this polar white blanks could be the cause?
I do not remember this problem in the past…may be I had luck?
Sorry I did not mean to infer that a particular blank manufacturer had an issue. Was using the reference to US generacilly. There are essentially three US Poly blank manufacturers.
…I d said before because Im not talking about 1 blank…the last 75 blanks from those brands (so is a problem with several brands hence my question) with the same situation.