Problem Shooting PPG K-36

Having a problem shooting PPG K36. My HVLP gun doesn't seem to atomize the paint, which is mixed 5:1 per the instructions (no thinner). The paint seems to shoot out in tiny splotches or dots, which don't flow together well. I tend to get an orange peel finish. Is this normal? I don't know whether I should expect a smooth finish or not since this is a high build primer and most of this gets sanded away. This is with a 1.7mm tip, 50 psi air pressure, and various paint flow rates. This is on lower cowl, after 3 coats of epoxy block sanded to 400 grit (first coat).

Thanks.

I used that primer and it worked very well. Just add some reducer to thin it down and it should spray fine. It was suggested to me to first prime with DP epoxy primer to seal the fiberglass prior to the build primer. Since you've already applied the K36 you can probably shoot sealer prior to top coat. Just ask your paint shop what they recommend for that.

K36

Noah,
I have an Accuspray HVLP gun and found that mixing the primer 5:1:1, Primer:catalyst:reducer works the best. If I recall, the data sheet recommends reducing the mixture. It seamed awfully thin when I first mixed it but it sprays well and doesn't run as I expected it would.
By the way, if you haven't already done so, you may want to take a close look at the 3M PPS system or the DeVilbiss, DeCups system. They will save a ton of time, solvent and materials. It makes using the gun almost as painless as using a puff can!
Carl

Your air pressure is way to high for an HVLP (High Volume Low Pressure) paint gun
PPG wants you to shoot that K36 at 10 PSI (at the cap) with an HVLP
40-50 psi with an old style Syphon Feed gun

BUT....
Something is in the gun, or something is loose..
Aircap may be loose or has dried paint behind it.

Dismantle the gun and clean it very well
Drain the water out of your compressor and lines
Adjust your air preasure
Make sure your gun is assembled propperly (everything is tight)

"Primer" guns usually get ignored during cleaning. And are often only rinsed with thinner at the end of use... 4 days later it needs to be used again and there is a huge wad of dried primer in there preventing good flow... I have a helper that is horrible about cleaning his primer gun (I quit letting him use mine)

K36 is a 2K build primer.. Reducing it will extend its pot life, but basically make it a very expensive sealer.

There are several other options if you are not needing a high build primer

As others have said, clean the gun. Special attention to the air cap. I had the same problem when I had a barely visible ring of paint on the ID of the center (main) hole of the air cap. A toothpick works well. Don't use metal!

Also check the packing nut on the needle. Clean, lube, tighten.

What's the ambient temperature, and which reducer are you using? I was having the same problem. I could spray for about a minute, but then the gun pretty much stopped shooting. Cleaning the gun revealed gooey gobs of paint clogging everything. The paint was setting up in the gun. This was with 870 reducer, in my brutally hot garage. I mentioned this to the guy at Tasco, and he said, "Oh, you're using the wrong reducer".

I recently shot some more, using 895 reducer. Much better results this time, still not perfect but much better. I can shoot for about 10 minutes before the gun has to be unclogged, enough time for 1 or 2 fairings.