I just received my G100 in the mail today. Didn’t come with any operating instructions. I’m just curious at what psi does the gun run at for spraying marine clear gelcoat? I’ve done some online searches and only found one site that states 80 psi. Is this correct? No other site states operating air pressure.
For very small parts and intricate corners I’ll go down to about 45 psi then upto 80 -90 for big jobs.
I think I use a #6 tip for standard gel and our VE tooling gell will use a #9 on big jobs as it’s a little more viscous.
Thanks for the reply. I’ll try it out and see how it works.
I’m having a hard time and making some major mistakes somehow… Today is the second time I’ve used the G100 cup gun with horrible results. I have major fisheyes everywhere. I’m spraying the marine clear metalflake gelcoat (60%) with Duratec high gloss additive (40%) catalyzed at 2% MEKP. The surface is a glass sheet that has been waxed with TR104 high temp wax.
I tried laying down a light, quick coat, let it sit for a couple minutes to let the initial solvents evaporate off then go over it again with 2 medium coats. This was a technique I used for clear coating. Using it for clear coating gave me great results. With gelcoat it’s just the opposite…
I then tried slowing down my passes and hit the surface with 2 medium coats with an overlap of about 30% thinking that the fisheyes would be filled in with the heavy passes. Still this method had bad results also. The only areas that didn’t have fisheyes were the areas that were soaked VERY heavily. I wouldn’t want to soak the surface that much because 1) it uses a lot of gelcoat, 2) it produces a heavier product.
I could only imagine the difficulty with complex, contoured molds… Laying up that much gelcoat would deffinately cause sagging.
Any tips on the air control setting or spraying techniques would be GREATLY APPRECIATED since my years of clear coating isn’t helping me out with gelcoating. 
Could it be the wax that is causing the fisheyes? When I roll on the gelcoat there are a few fisheyes but they go away after i roll over the area again. I’ve done some youtube searches and their surface finish is very textured. They’re making fiberglass parts with tooling gelcoat so the texture doesn’t show on the finished product. Is that texture acceptable for carbon parts with a clear gelcoat? In the sheets I’ve made previously any texture in the gelcoat can be seen in the carbon of the finished product.
I have the G200 Gun (same but with the catalyst add on) and I only use it with tooling gelcoat for BIG molds because it sprays big amounts of gelcoat.Sorry to tell you but it’s impossible to spray a near perfect (without orange peel) surface with this gun. One solution would be to increase the pressure and reduce the thickness of the gelcoat using aceton, but again don’t expect to flow like clear coat.
As fas as the fisheyes probably it’s the wax u’re using.If you’re using semiperm it’s definitely this, gelcoat doesn’t like it.
Always diassemble this gun to clean it after every use…I know it supposed to save u time from cleaning(that’s the reason I got it) but after few times using it, the holes and rubbers seems to clog.
Thank you for the reply. Not good news but atleast it’s some info on why I’m getting the results I do. I’ll try to raise the pressure and thin the gelcoat to see if that helps. If not then I guess I have to look into another solution. Thanks again.
I had better results with an ordinary gun with a 2.5 tip 
Yes I have better results with a 2.5 or 3mm tip. Also change wax to tr 108 it will solve your fish eye problems. Tr 108 is compatable with pva not that you want to use pva but you can wax the mould and then spray pva straight over it without fisheyes, you need this characteristic when spraying anything with duratec in it.
^ What he said. It’s why you find the same wax being used in most recreational boat factorys like Four Winns, Malibu, MasterCraft, Regal, and the list goes on an on… Gotta make sure those in hull graphics look good when they come out of the mould.
Thank you very much for the info. I’m ordering that wax tomorrow!!
Just an update. I ordered the TR108 and the wax stripper. Stripped the TR104 residue build up off and laid up the glass with 3 layers of TR108. After cure I rolled out clear gelcoat and very few fisheyes appeared. Another roll in the other direction and they were gone!
thank you very much Brad1 and Rotorage for this suggestion! It has helped me out alot! 
You can use a thinner tip with duratec top coat for a very low orange peel surface. No surfacing wax needed :). I got a G100 gun cup a few weeks ago and LOVE it. I wanted the G200 but my partner was against it. I agree now. The amount we spray; we’d never use the guns potential if it had the in gun mix system.
Maybe one day :).
How hard is it to adjust the G200 between 1% and 2%? Is it a trial and error type of thing or what?