Brush on my tooling glecoat?

General Composites Discussions Composites Talk
#1

What do you guys think? I’m considering brushing on some tooling gel since I don’t have any of the necesary spray equip. All I’m looking for is a nice smooth surface on my mold, I’don’t care about brush strokes or anything since it will all be covereid in glass anyways. Do I run the risk of getting bubbles stuck and getting bubbles in the surface of the finished mold?

Also I bought a little can of tooling gel, it is very thick, is this normal? thei is my first experience with this stuff.

Thanks.

#2

it sounds like you bought is epoxy tooling gelcoat. If so, make sure you use epoxy resin with it. best way to apply it is with a squeegie. you want it very thin, between 10-15 mils is the best

#3

it’s polyester gel coat, because it came with a mekp hardener.

#4

If you are making a small mold yeah you can use the, pour - brush technique. I did it on my last mold and it came out fine. just the outside corners of your plug ( inside corners presented no problem) do two coats of PER tooling gel coat. Otherwise it won’t be thick enough on those edges. I just use the brush to move the puddle of gel coat around… not actually brushing it on.

aim for a 30 mil thickness, but it won’t be even on all surfaces because of the method of application. It’s ok…it will still work fine.

#5

After brushing on the PER gel coat on a small mold, you can pick it up and shake it to get the resin to self level.

But Fastrr tip on adding a second layer on the edges as those will run off and get too thin is good advice. If you have another color gel coat, add that to your plug last so if you are sanding on the mold (don’t do any sanding unless you really have too) and the surface changes colors, you know you are close to the glass.

#6

I’m only brushing my gelcoat on for my molds… surprisingly, the label on the can says something like ‘Brushable White Gelcoat’ :slight_smile: Anyway, gives a good surface, have yet to get any air bubbles in it.

Needs two coats though… and it’s best to coat it on as thick as you can… if it’s too thin, the resin from the when you lay the glass makes it go ‘soft’ again, and the resin then eats into the plug.

Also, if it’s too thin, it doesn’t cure… the man at my composite supply shop says that it relies in a certain amount of mass to effectively cure. And it sucks when that happens :smiley:

#7

great advice guys,

malcolm, isn’t too thick going to lead to alligatoring??

#8

Shit mate, I’ve not very little experience, so don’t take anything I say as gospel. I can tell you though, in my experience, too little gives me alligatoring… it’s something to do with not enough mass to cure correctly according to my supplier.

I’ve done a few experiments, and I’ve found that lathering it on, or even pouring it on, works fine. YMMV, I’m using gelcoat specific for brush coating.

#9

I just recently brushed on tooling gel to make a mold. I let each layer cure to a “squeaky” surface before proceeding, it was a 2-3 hour cure for each layer if I remember correctly.