It has finally warmed up in New England and i am glassing winter projects. I am going to put boards under a black poly tarp to bake. Do i bake the hot coat and then gloss?
Do i bake the gloss before polishing? or, do i polish and then bake? if so, does the polish fade? what are the tricks here?
Firstly, I believe baking refers to post curing. Post curing being just that. Post (after) curing. Never had any problems with room temperature curing in either laminations or hot coats with epoxy but it’s a good idea to keep the temperature of the room reasonably constant for the first cure.
If you want to oven bake your boards afterwards then so be it. But that’s something else.
So do you mean just let them cure for say 24 hours after the hot and then gloss coat? if so, then if i “oven cure”, should i do it after polish?
Cure the board before you polish
I’m assuming that you will be polishing the epoxy filler coat?
Or the gloss coat will just be more of the same epoxy?
The harder the resin is, the better it will polish, so post curing is good.
You do risk the shine fading if you heat it up after polishing.
Depending on how light the EPS is, be very careful when baking, you don’t want to delaminate the board.
2# EPS you might be ok if you stay under 40 degC (104 F), anything lighter or hotter and you’ll really want to vent it - vent it and be safe!
Kit
Deanbo and KKSurf, thanks for the replies.
this is EPS 2#. i am using Resin Research with Additive F for everything, including the Gloss coat
so let me get this straight
hoat coat, then gloss coat, then oven post cure/bake, then polish?
Sounds like a good idea to me. There is curing and then there is post curing. So you can cure epoxy twice if you want to. When laminating, fill coating and the rest, the temperature should be around 25 to 30 degrees. That way you give the epoxy the best chance to do it’s first cure.
I’ve never taken the second step and post cured but Greg Loehr should be able to give you time and temperature for post curing as well as how long to leave the board before post curing.
Yep you got it Chilly
As Dean says, post curing is not absolutely necessary, but does add strength to your resin (and hardness, and and…)
If your glassing in a warm environmentand and/or fast hardener, the returns from postcuring will decrease.
The slower the hardener, the more necessary postcuring is, and the hotter you need.
The slowest hardener I use pretty much has to be post cured, otherwise it says really “green” (soft, partially cured) even in summer.
With a fast hardener in a warm place, you can get away without postcuring, and most people probably realistically don’t manage to get 40 degC for 8 hours anyway, which is an average postcure schedule. The resin will polish fine in this case as well.
Kit
I have been using the slow cure.
Weather is back in the 60s tomorrow but i have 2 boards glossed. i will wait till warm weather and then post cure. I will let you know how it turns out. Thanks for the guidance!