Looking for fine screen to sift sandblasting sand

[u18b]

I airbrush with Nitrogen which is also dry and no need of a trap.

But if you use a compressor with air you MUST have a moisture trap.

Think of it this way.  Compressed air cools when it is released through a small hole (expansion valve).
Well, cooling air condenses the moisture in that air.  So any moisture will form small droplets of water as you airbrush.

[peteski]

If the air compressor has an integrated air tank (like most do), there is usually a highly visible warning label instructing the user to drain the moisture from the tank daily.  Some moisture does condense (and has t be drained) while some remains in the compressed air. Then, like Ron mentioned, will condense into water droplets when it is decompressed (sprayed out of a small orifice in the airbrush nozzle).

[craigolio1]

My compressor is a small one with a tank.  I pull the plug on the bottom prior to every use.  Do I still need a trap in the airbrush line?  How much moisture can be added in three feet of hose, or am I understanding this wrong?  I've painted many many models in both water and laquer based paint with no water issues, that I could recognize anyway.

Craig

[peteski]

My compressor is a small one with a tank.  I pull the plug on the bottom prior to every use.  Do I still need a trap in the airbrush line?  How much moisture can be added in three feet of hose, or am I understanding this wrong?  I've painted many many models in both water and laquer based paint with no water issues, that I could recognize anyway.

Craig

Hey, if you're ok without a moisture trap, there is no need to add one. The moisture is not coming from the hose. It is present in the ambient air the compressor sucks in and compresses. Since the compressed air is denser than the ambient air, it has more moisture per square centimeter. The process of compressing the air squeezes some of the moisture out (which condenses on the cool walls of the tank). But some of the water vapor (moisture) remains in the compressed air.   Spraying that compressed air through an orifice causes it to cool as it decompresses (goes from a higher to a lower  pressure).  That cooling is what will cause the water vapor in the compressed air to condense back into water.  But the amount of condensation might be very small (depending on several factors).

However I don't think that moisture in the air is causing your sandblaster to clog up. The clog is (in my experience) in the suction tube in the jar.  The compressed air is nowhere near that area.  Like I said earlier, I think this due to a bad design of the sandblaster.  I just live with it.

[craigolio1]

Thanks for the physics lesson Peteski. Reading I feel I should have been able to figure that out my self. I agree that the suction tube is the issue. That's where crap gets stuck for me. I'm still going to sift if because I have found chunks.