Weird problem when trying my new airbrush.

usmc1371 wrote:

I use a Paasche H external mix airbrush similiar to the Badger 350.  I have a horrible time spraying MM acrylics through it.  The paint drys way to fast and clumps up.  I think it has something to due with the higher pressures needed for the siphon feed, external mix airbrushes.  I don't have as much as a problem with Tamiya acrylics.  I usually have to thin them 1:1.  I also don't have as much problems with the Acryl paints when using my Bader 100 which is an internal mix, gravity fed airbrush.  Of course, the air pressure is much lower with this airbrush.

Jesse, I think you were spot on with this problem. I just got a Badger 200-NH (Internal Mix, Single Action). I hooked up the same exact bottle of thinned paint that was giving me fits with the 350. I had mixed it with Testors Acryl thinner, which probably made it dry even faster. It sprayed just beautifully with the new 200. No problems at all with paint drying on the tip, plus as you said, I could run it at a slightly lower pressure.

  I think I'll dedicate the 350 to spraying laquers and maybe enamels if I ever use any. It sprays Alclad just fine.

 

 Oh, and thanks for your help guys! 

BTW... are you stirring the paint with something, or just shaking it ?  it has to be stirred... a lot. I use a small pallet knife, and depending on how much pigment/solids are intere it can take several minutes of stirring before the solids are dissolved.

I notice the Tamiya paints I have been using recently, dont seem to have as much un-dissolved/settled solids as do the MM acrylics I have used.

I have a badger 200 myself, the only time I ever get this problem is when I am trying to spray testors chrome silver... enamel

I use a Paasche H external mix airbrush similiar to the Badger 350.  I have a horrible time spraying MM acrylics through it.  The paint drys way to fast and clumps up.  I think it has something to due with the higher pressures needed for the siphon feed, external mix airbrushes.  I don't have as much as a problem with Tamiya acrylics.  I usually have to thin them 1:1.  I also don't have as much problems with the Acryl paints when using my Bader 100 which is an internal mix, gravity fed airbrush.  Of course, the air pressure is much lower with this airbrush.

In regards to the paint being to thick, I don't necessarily think so.  I've sprayed Tamiya's Liquid Surface Primer through my Paasche at about 8 psi without the primer being thinned.  That stuff is thick!!!  I really didn't have any clogging issues because the primer wasn't drying on the needle.

-Jesse

What compressor do you use?

 I'm using a small automotive type with a 2 or 3 gallon tank. It's an off-brand, but the tank is pressurized to 150psi. I got it as a christmas present last year, so I spent a few bucks to add a regulator and an inline moisture filter to it. I don't spray when the compressor's running and the tank holds enough air to use it for quite a while at the little bit of CFM the airbrush is pulling. I watched the pressure drop on the gauge and it looks like it drops less than a pound or two(not the most accurate gauge in the world) when I spray.

 

My guess would be a blockage (lump, chunk, dried piece off the bottle, ect) or your paint was not thin enough.

That might be the case. I had a gut feeling that my paint was too thick for the fine tip. I was going for the consistency of the proverbial 2% milk, but I have a hard time judging that.

Later, I carefully inspected the needle and tip under a magnifying glass. It was smooth and clean, but that was after I ran hot water and windex through the brush. I could have had a spot of dried paint clogging it while I was spraying.

 

Fill your cup with thinner (or water) and spray it out on a piece of cardboard to see if it happens again.

Come to think of it, I remember spraying on some cardboard when I was running the hot water and Windex through it. It sprayed just fine. So I guess that would lead to a conclusion that the paint was too thick?

 

dmk wrote:

Hey All, I just got a new Badger 350 and tried it today with Testors Model Master Acrylics and the Testors Acrylic thinner. I'm using the fine tip.   The Badger manual said to run the brush somewhere between 15 and 50 PSI with 30 PSI nominal so I was using between 20 and 30 PSI varying the pressure and tip adjustment to try to get the smoothest spray. It seemed to work best between 25 and 30 PSI.    The weird thing though was the brush would start to paint a line, then stop spraying paint (but would still blow air), then it would start up again and as long as I held the button it would spray fine, until I released it. Then it would again spray a bit, cut out, then resume and continue spraying.   Has anyone seen this before?

Yes, many times. It is a typical description of using an external-mix, siphon feed airbrush with a low power airbrush compressor. Unfortunately, it is the usual combination that beginner user gets. What compressor do you use with the Badger 350? It may be the key.

I see that you have a very methodological approach to arrive at the conclusion that it works best at 25-30 psi. It is good. Check to see if the pressure drops (from 30 to 15 psi or lower) when you start spraying. The compressor needs to supply 0.4-0.7 CFM up to 45 psi to work properly with an external-mix, siphon feed airbrush. Most inexpensive (below US$100) compressor cannot keep the pressure at even very small flow. These inexpensive compressor will work ok with internal mix, gravity feed airbrush, but not the cheaper external-mix airbrush.

If my guess is correct, there are two work around.

(1) Thin the paint as much as necessory, typicall 1/3 to 1/2 thinner ratio for MM acrylic.

(2) Learn to paint in pulses. Release the trigger before the pressure from the compressor drops too much.

That makes airbrushing a chore and not fun at all. I did that for many years and eventually upgraded. Now I wish that I had done the upgrade years ago. Search for "compressor" on this forum and you will find many discussion on this. Good luck.

 

My guess would be a blockage (lump, chunk, dried piece off the bottle, ect) or your paint was not thin enough. Fill your cup with thinner (or water) and spray it out on a piece of cardboard to see if it happens again.