Hi, I am using the gelcoat gun for the first time. I am trying it with a white low viscosity polyester gelcoat designed for spraying. The gelcoat manufacturer recommends 2-3mm spray nozzle at a 5-bar pressure, so I am using FN3 (2.4mm) nozzle. The cup is half full and you can see on the video that there are small drops falling from the nozzle when not spraying which I think is OK. However, when I pull the trigger, very little gelcoat is flowing, just the first drop. I tried to increase the pressure up to 8 bars and it's all the same - no gelcoat is flowing, just the air at a high pressure. The compressor is 256 l/min (9 cfm), 10 bar. Do you have any idea what's wrong?

I would suggest trying one of the bigger nozzles, initially, as the FN3 feels a very small one to be using for gelcoat

I tend to use the FN6 for gelcoat and use the FN4 for spraying pattern coat primer which has been thinned down quite a bit with acetone.

If this doesn't fix things, I'd then look at the cup set-up to make sure that everything is sealing correctly

As said probably too small nozzle.  Your flow rate and pressure seems perfectly reasonable for gelcoat spraying.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

It worked with FN6!

I have another gelcoat that's designed for spraying, but this one didn't work well - see the picture below. Instead of consistent flow of aerosol, it's spilling chunks. I tried both FN6 and FN7 nozzle. I also tried to increase the pressure from 5 bars up to 8 bars with the same result. Do you think it's not intended for use with this gelcoat gun?