Watch out!!! This could be dangerous

General Composites Discussions Products Talk
#1

I’m just not having a good day today. Woke up this morning and its raining… so I say to myself this sucks. So I take my time and make it into the shop, turn everything on and start to setup. I got everything ready, mixed my epoxy and what do I have in store……… My box of brushes is empty.

Great so what to I do??? Run to the store?? No way I search for an hour around the shop for a brush, so to make a long story short I found a 2” foam brush.

Now here is the crazy part. The brush with epoxy on it starts to smoke!!! That’s right Smoke like it was on fire, but with no flame. Then in about 5 minutes the foam brush is as hard as rock.

I never seen this before mainly due to the reason I only used normal throwaway brushes. I have read that foam is good but after this I am sticking with what works! This is just a heads up for anyone that wanted to use foam brushes… Watch Out!

Bill

#2

Yikes! Same goes for foam cups too guys. Same thing happened to me, but in a foam cup. I have used foam brushes before too and it is a little better. However, after a while all it does is soak up the epoxy from the working surface. I find myself wasting a lot of epoxy when working with a foam brush also so now I am back to the chip brushes.

#3

Wow, I’m glad I read this before I started anything. I picked up some foam brushes at Home Depot the other day because they were cheap. Guess I won’t be using those for this! Thanks for the warning!

#4

I’ve had many foam brushes start to smoke, but its not actually because of a reaction with the foam as I found out. Mixed epoxy resin cures at different rates based on a few main things, the type of hardener used, the temperature, and the amount mixed… The more mixed epoxy you have mixed in the same cup (or any other small spaces), the faster it will cure. Coincidentally, foam brushes soak up a lot of resin–causing it to reach very high temperatures (can be well over 200ºF easily). The same thing will happen if you mix some resin and just let it sit in the mixing cup until it hardens. Its more steam than smoke I’m pretty sure.

Along these lines I was wondering if anyone had used the foam in mold making? Once my first brush hardened like steel, I got a lot of ideas… :idea:

#5

You’re right about the foam brush. As far as using foam in mold making, I have not done or heard of anyone doing it so far. If time permits I’ll be starting on a new spoiler project that will require foam/honey comb sandwich mold. But other than that I haven’t had any experience with it.