Hot Rods Shooting catalyzed primer

I am having trouble getting my DeVilbiss GPG 516 gravity feed gun to shoot catalyzed/high build primer. I have to use a very narrow fan pattern And what seems to me a lot of pressure (over 40 lbs) to get it on wet. Is the primer too thick for my gun, do I need to mess with the air/fluid mixture, or is it possible to thin the primer? Any suggestions would be appreciated.

 

What size tip you running ?

 

Yup what tip? Most high builds spray best with a 1.8 or larger.

 

Hey Belair run by HF and buy that $10 HVLP. It works great for primer. It has the 1.8 tip in it. This one listed below may or may not have the 1.8 tip, it's just an example.

http://www.harborfreight.com/20-oz-high-volume-low-pressure-gravity-feed-spray-gun-47016.html

 

I believe it is a .80 tip. Is that the problem? Thanks for the help

 

You better check that.
But Yea, it should be like 150-200% bigger than a .8

 

If it is a .8 that is extremely small especially for high build. I am surprised you are getting anything out of it. Is this a mini gun or something?

 

Wow, do they even make a tip that small? Is it an airbrush?

 

No, it is a full size. I could have misread it, but I will double check tonight. If it is a 1.8, what am I doing wrong?

 

Might be just too thick and you need a 2.2 for that material. A small amount ofcompatible reducer will help get it out of the gun, but doesn't help the "high build" aspect of what you paid for

 

The only other thing to check before going to a different gun with a bigger tip is the lid. Is the vent the hole in the top of the lid open? Maybe partially clogged? Check that first.

 

My sata klc is a early 1.8and shoots every primer but slick sand well. Only time it doesn't is when the vent gets plugged, easy to do with a full cup and lots of movemen.

 

Yep, that vent plugged will do it

 

If he [op] is new at spraying the primer I think he is better off to thin some and test some..High build I was told can "bridge] imperfections if applied thick, probably old world high builds were problematic and the new stuff is no worry but couple lighter coats can't hurt??

 

Had this exact conversation with the ppg rep the other day. Using the wrong temp reducer actually causes this. If you try to rush it by using a fast reducer, it will bridge instead of soaking in. It will look good for a week or so, then shrink. He kept calling dt870 the antichrist. He kept pushing dt885 because it soaks in more.

 

You could try reducing slightly with urethane grade reducer, but not too much or you lose the high build, and you may have to lay down more coats for a good film build.
or you can get yourself a cheap HF hoser gun say a 2.2 tip, and try with that, open that needle and turn up the air a bit.
I have shot 2 k urethane high build primer with a cheap HF gun with a 1.4 tip, I reduced the primer, with urethane grade reducer about 10%or so, shot on a like a dream, flashed super quick, and shot on extra coats for a good film build with less shrinkage.....good luck

 

You can't beat this site for great advice on how to fix the problem.

Jimbo

 

does your cup have the little filter in the bottom? i have never been able to use them with primer.

 

The cup filter is long gone, I strain it twice to make up for it. I will double-check the vent.

 

And with a HF type 1.8 gun I've used on Hi Fill Catalyzed primer---It LIKES higher pressure. certainly higher pressure than anything with less viscosity does. BILL RINALDI

 

Just shot some primer tonight on my old trucks fender.
This primer is an industrial enamel type, much like a high powered rusto metal primer.
It is super thick, but I reduced it down with straight xylene, and shot it out of a cheap gravity flow HF type gun with a 1.5 tip.
I opened that needle up and turned up the pressure, shot nice, big wide fan, and it was around 75 outside, flashed nice and quick, 3 coats one after the other...