Overly cautious?

General Composites Discussions Composites Talk
#1

I am laying up some large boxes made of chopped strand mat fg. I am using 2oz weight mat; VER with 2% mekp.

My ambient shop temp is around 87F degrees.

How many layers at one time can i lay before having to worry about shrinkage or overheating the laminate?

Sounds silly but i don’t want to mess up these boxes due to time and $ invested.

I always lay down my gel coat, let it set up for 4 to 6 hours, then one layer of 1.5oz mat. Let that set overnight. Rough sand, prep the surface for next layer.

I have been waiting like 2 hours in between each layer but it would seem the chemical bond may not be enough between layers? I catalize with 2% mekp. That and i don’t want to have to de-nib each layer before the next goes down.

I had a good laugh with a fellow fiberglass biz owner… he had a guy come in for a job position who said, " I know everything about fiberglassing", and " It’s fun".

I’ve made lots of fiberglass molds but i can’t tell you how many layers before warping or shrinkage get out of hand. And like i said I can’t afford to lose time or $ on this customers project.

I’m looking to speed up the process without switching processes altogether.

#2

3 i would but some may do more.

#3

It depends on the resin system and specific catalyst that you are using with it. Every system will be different. Contact the manufacturer.

#4

hmmm, well without going way into specifications on specific ver resin systems i think that maybe the general rule of thumb might help. if shrinkage is anywhere near an estimated 7% or more with the system you have been using i would think and argue that the more material by volume you lay the more shrinkage you will see.

whats your gut feeling telling you?