Question about Paasche

If you are getting a "pulse", it sounds like it's coming from your air source. What are you using?

Based on my previous experience, I would suspect it's a piston type (or reciprocating) compressor, in which a piston moves back and forth, compressing the air. This may explain your pulse paint pattern.

If you are using a compressor, you may want to look at having an air "accumulator", which would give you a constant, steady air source. The compressor would fill an accumulator tank, and you would regulate the air pressure coming off the tank. A steady source of air should not pulse. You can buy a 5-gallon portable tank at Wal-Mart, I believe they are under $30. You'll need a regulator, if you don't have one.

Or, if money is not a big issue, you could buy a compressor set-up that has a built-in tank. Here is one on e-Bay, which is where I bought mine.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=22662&item=4355578576&rd=1&tc=photo


Good luck!

1) Too much pressure ... I'd recommend lowering your pressure to around 10 psi if your airbrush will reliably spray at that pressure, and thinning the paint enough so that it will flow at that pressure. At 20 psi the overspray is making your lines wider than they should be. If you can't get 10 psi go as low as you can while still getting reliable paint flow.

2) Angle the airbrush into the area you are painting so that the overspray on the outside of the line is less.

3) I can't think of a way to ask this delicately, so ... Are you experienced with an airbrush? Too many people think that an airbrush is going to give them instant artistic abilities right out of the box. The key to thin, straight, even lines is practice, practice, and yet more practice.

To be frank I'm a rookie with an airbrush use ... but I don't think it's the compressor problem...the compressor is "dry diaphragm" type without lubrication with small air tank.
And about the air press...I tried few set-ups on the airbrush from 10 psi up to 30 psi and still I can't find the right set-up to spray fine line.

QUOTE: Originally posted by MACooke Based on my previous experience, I would suspect it's a piston type (or reciprocating) compressor, in which a piston moves back and forth, compressing the air. This may explain your pulse paint pattern.

It is not piston compressors that do that, it is diaphragm compressors that pulsate.

Mike

My mistake, I didn't read Lionking's post thoroughly enough. What's the difference between a dry diaphragm and piston type? I have an old IR piston compressor, and my lines used to "pulse". Now that I have a compressor with a 2-gal. tank, I don't have that issue.

Sorry, y'all.

I've never used a Paasch SA2000, but looking at the description of it from Paasche's website, it seems to be the moral equivalent of my Badger 200NH, so painting a clean fine line should not be a problem. Have you experimented much with your paint/thinner ratio? When I was first learning to use an airbrush (not that long ago, so I remember my learning curve well), my most consistent mistake was to not thin my paint enough. It almost as though I needed to thin the paint beyond what seemed to me it should be.

SInce you experience the same problem with another AB, I still wonder if your compressor might be playing a role. How does your compressor's output pressure vary from the instant you press the AB's trigger commpared to after several seconds of continuous output? Since it has a tank, I would assume that it should be relatively constant, but I am wondering if that is truly the case.

Sounds an awful lot like a paint flow problem. Did you check the tip?

I use a Paasche H and I find 25psi with the #3 tip closed up to the point where you are just barely getting anything out the best way to go. This requires a relatively thin mixture of paint. If you are using acrylics you don't need much if any thinner but it gets tricky as tip dry becomes a problem (paint drying on the tip and clogging the nozzle). If you keep the brush going you can manage. If you stop for any length of time you have to open the nozzle a little and blow it out, then re-adjust back to the right setting. There are special inhibitors you can get for acrylics to keep them from drying too fast but I haven't had to use them yet. For enamels you really have to thin it out, at least 50/50 or even 2/1 (thinner/paint) mixture. Experiment, practise and have fun!

I noticed on Paasche's web site that the SA2000 has three tip sizes available. Which one are you using? If you are using the small tip it may be too small for model paints to flow through reliably.

I don't think it's the compressor. A tank of any size should buffer any pulsations from the motor and prevent them from showing up in the airflow, or at least minimize them. Since it happens on two airbrushes I think the problem is in technique.

Are you using enamel or acrylic paint? If it is acrylic wipe the tip of your airbrush off with a Q-Tip moistened with thinner FREQUENTLY. I wipe mine down every time I sit the airbrush down. With either type, try thinning it a little bit more and using the same pressure and see if that helps.

Operated by themselves and hooked directly to an airbrush, any air compressor will produce pulsing. A tank in the system absorbs the pulses before they reach the air brush and also maintain a constant volume of air and pressure for a longer time.

Most diaphragm aircompressors (especially the lower priced ones) don't have any form of tank so the pulses are passed directly to your airbrush. You can reduce or eliminate the problem by adding a small tank in your system. Several years ago, I had a modeling friend that was given a small diaphragm compressor by his wife. He liked it because it was fairly quiet but the pulsing and lack of a regulator drove him crazy. As he didn't want the noise and expense of a piston compressor with a tank (they lived in a apartment), we rigged a system with a tank in it for his compressor. I swapped him a small high pressure oxygen tank for a couple of models. The tank had a fitting at the top which contained a guage that showed the pressure in the tank, an open/close valve and the inlet/outlet to the tank. We went to a welding supply shop and purchased an adapter which screwed in to the inlet/outlet opening and gave us a 3/8" NPT pipe to which we added a T fitting (3/8" NPT on one side and 1/4" NPT on the other two). We hooked the compressor up to one side of the fitting and a regulator with a quick disconnect fitting on the other. Worked great. The only change I would make today would be to use a 10 or 20 lb fire extinguisher instead of the oxygen tank. that would allow the tank to be stood next to the desk. (the oxygen tank had round ends so it had to lay on its side). Depending on how good you are at scrounging, you should be able to rig the same type of set up for under $30.

QUOTE: Originally posted by MACooke My mistake, I didn't read Lionking's post thoroughly enough. What's the difference between a dry diaphragm and piston type? I have an old IR piston compressor, and my lines used to "pulse". Now that I have a compressor with a 2-gal. tank, I don't have that issue.

A piston-compressor has, a piston driving the air (no kidding).
A diaphragm compressor has a diaphragm that pulsates in and out sort of like a bellows. That is why they pulsate because of the movement of the diaphragm.
A piston compressor can pulsate slightly but it not near as pronounced as a diaphragm model. You can, as was already mentioned, add any size of airtank to one and smooth out the airflow though. Even a small fire extinguisher bottle will do the job on the compressors that do not put out high psi.

Mike

Hi guys.... THX a lot for your help

I'm using Humbrol Enamel paints (the only option in my country) and I thin them up to 50/50 with synthetic thinner.
Now that I read your comments I think the problem is that the paint is drying in the tip and clogged. it doesn't matter what size of tip I use (#1 or #3) the same phenomenon.
Another thing is I use the metal paint cup which is open and I guess that the thinner is evaporate quickly ... do you seal the paint cup to avoid that???

about my comp ... the comp is running all the time I use it, it have a tank with relief valve ...which means no "over load" on the comp, also I have a press regulator and a water trap on the line to the A/B ... not bad for $100

I don't think the open paint cup makes much difference, I would try thinning the paints more than 50/50 and that should help a lot, especially with Humbrol enamels.