Dump Gun / Tooling Gel Coat

General Composites Discussions Composites Talk
#1

Saturday will be my first time using a dump gun to spray tooling gel coat.

I have a #6 and #4 tip.

What is the recommend PSI for spraying it straight up? No reducers, just straight gel coat.

Any other tips / tricks?

Thanks!

-Andrew

#2

the last time i used one.i still had to thin my tooling gel coat with a little bit of acetone.otherwise it was going on with too much orange peel.witch is not good for your first ply.you should do some test sprays on some paper tacked to the wall.this will give you a little practice with spraying.it will take a few tries to get the hang of tipping the gun down,then spraying,then tipping the gun back up.if you hold it in the down position the gel coat just runs out the tip.

#3

Duratec Clear Hi-Gloss Gel Coat Additive 904-001 is better to thin gel coat and enhancing tooling gelcoat properties. Here some good info on how to use it with Gel Coat, just don’t get from fiberglast they are way over price.
http://www.fibreglast.com/product/LC_005

Cheapest
http://www.expresscomposites.com/

#4

yea,your right.i just started using the high gloss additive.i forgot it also thins the gel coat a bit.

#5

Depending on the brand of gelcoat, you might be lucky to not need reducers. If reducer is needed, don’t go over 5%, but 2% generally works fine. Keep it to a minimum.
#6 nozzle is probably the smallest that will work for you, likely using reducers. #8 will probably be better.

Spray at 15psi (test with trigger depressed) and hold about 24" from surface.

#6

well i did everything about opposite from what was posted here because i didn’t have time to wait for an answer - heh

i was putting down tooling gelcoat on my plug (inside coating of the mold), then a few layers of glass.

i didn’t thin, sprayed at like 50psi i think it was, but i did keep it a good 24" above the part.

all well, live and learn.

i will know in a day or two when i pop the mold from the plug on how it turns out.

#7

High air pressure will cause a very textured gelcoat back side to lay up onto, as the air stream blows around the gelcoat on the surface.

#8

found that out!

but its ok because it is the back side.

i took my time on the first two layers off mat - no air bubbles :cool:

for the future, i will “play” with the gun more to try different settings.

the gelcoat was so overwhelming vapor wise - i may not have laid enough down… i’ll find out after i pop the mold… might require resurfacing sooner then later.

all well, live and learn.

#9

it looks like you got your gel coat down pretty flat.so you should be good.if its too lumpy.you will have problems getting your first few plies down without voids.you can use a mil gauge to check your gel coat thickness.its just a small piece of aluminum that has marks for mil thickness machined into the side of it.i check mine on the edge of a flange.