I am planning to glass my first board (8’ pu blank and 6/6+6 glass) shortly and trying to decide if I should go with epoxy or polyester resin (not uv). My thoughts are that epoxy seems to be a more simplistic medium to work with and I am curious about the opinions of others.
My take (pros) –
Epoxy: Mixing ease, more consistent in temp and humidity fluctuations, longer work times (though could be a con working outdoors).
Polyester: Control of gel times, easier saturation of cloth, no worries of frothing.
Issues such as board flex, strength, and uv resistance do not really concern me - but, a sticky blob of uncured resin sitting in my backyard does. I will be working outdoors in the shade (78-85) and have been factoring that into the equation.
However, as you have noted, the cloth saturates easier with polyester and you can ease on down on the catalyst to increase pot life, as you mentoined a key phrase: ‘first board’. Slow and easy is good. Making your first board bulletproof - naw, you’ll want to surf it for a while, learn from it and make another one.
Try to pick the cooler days or glass as early in the day as you can, right after the dew has settled. That `10 degrees F will make a difference in pot life, and as the day heats up you should be done and the resin can cure nicely. .
What would be the approx hardening time on the epoxy (for both the fast and regular hardener) at those approx temps - any rough ideas?
Cost considerations - also a good point. i.e., Most of the stuff will probably end up on the ground, in my hair, and on my dog, haha. With hopefully the remainder finding it’s way onto a first shaped board.
For a glassing newbie, I’d recommend glassing with Lam resin with the UV catalyst already added. You can by lam resin with the UV catalyst premixed from Fiverglass Hawaii. great stuff.
Benefits of this are near unlimited gel time allowing you to glass the board without panicking about gelling. Great for newbies.
No catalyst to mix, so no worries about ratios
Temperature is not a factor as all you need is daylight to cure the resin
Humidity affects only the cure time once exposed to UV light. If it is humid it will take a few minutes longer, once UV resin cures
Depending on intensity of sunlight and humidity, your talking anywhere from 5 minuted to 20 minutes. the other day I cured the bottom of a lay up in 2 minutes…bright sunny day with no humidity.
MEKP cured resin, though cures acccording to catalyst amount ratio, it still needs another few days for the chemical reaction to fully cure. Once UV resin cures it it is fuly cured. 20 minuted tops.
NO MEKP means the resin is less brittle and thus strnger and is a bit friendlier for the environment. Though nowhere near as safe and friendly as epoxy.
DRAWBACKS…
You need an environment that is nearly free from UV light. I glass in a garage and cover the windows. I;ve gotten to the point that if some light gets in then that is OK because I am much bettter at glassing. But for the first few imes I’d reccomend creating as free an environment as possible from UV light.
When doign cutlaps you have to be very careful that the rails do ot cure prior to trimming up the laps. If you flip the board over thy could cure in a matter of minutes and then your screwed. I cure the bottom and then take the board into the gargae with the door open and let the rails half cure before moving further into the garge to trim off the laps, then expose to full sun to final cure the rails.
You cannot use UV resin for things like finboxes or doing very dark or opaque colored tints. UV light needs to fully penetrate the resin to the surfacceit is onding to in irder for it to cure. However you can certainly ad MEKP to UV resin for things like finboxes etc.
Use epoxy, (RR epoxy) low VOC’s and super easy to work with. I live in Fla so I know about heat and humidity. I used slow hardener and also worked outside, shade approx 88-92 deg , no problems at all. The epoxy just slowly thickens, so you know when its going off and still have time left to work it. Soaks in very well, just put it on, sit for a minute , and thats it, just squeege out the excess and you are done. I worked in poly for years(boats,pools ect…) and now that I have this epoxy I realize just how much polyester resins suck. The clean up is easy(RR epoxy),I don’t even have acetone around anymore, use gojo,alcohol and disposable cups and gloves…simple. Sands great and prep work between steps is a dream.Just be super sure of mixing it throughly…when you think your done…mix 2 more minutes. You will be so happy if you keep clear of that poly crap…oh yeah, I have yet to see the “frothing” issue people speak of, whether mixing it or pulling the excess off the laminate…peace and waves…
My hardener is supposed to be 240 mins, I got the slow stuff from Greg. I never took that long …lol…just always finished up and check it later. I know out in the heat a few times it went off quicker than that…but I was long gone ,off doing something else. Not to offend anyone…but poly sucks…why breathe that crap in…when you don’t have to??? Cost considerations?? No way is poly cheaper…use what you want…have fun,good luck…peace and waves…