You might be curious, why the hell is that dude writing all that stuff all over again? Didn’t he write something on how to choose the right air compressor? Yes indeed, but it was a long time ago and to be honest even I don’t remember what it was about. After extending the best airbrush article for price ranges I checked the one about compressors again and found out that not everything has been said.
I decided to take a closer look at the compressors used for airbrushing, go through every piece of the whole compressor machine and question the need of those pieces.
Industrial compressors, have their good qualities (good air pressure and low price) but are still too big and noisy. Because of that there isn’t that many people using them at their home environment.
To convince regular user to build homemade compressor is actually pointless right now but if you want you can find many instructions over the Internet or just follow this or this.
Especially, in our case, airbrush compressors could use oil or be oil-less, another categorization would be piston or diaphragm types. Oil-lubricated compressor is actually something similar to homemade – compressor from refrigerator connected to a nice tank and painted with nice color. The cost is definitely incomparable with homemade machine even though it is actually the same thing.
What is nice about oil-lubricated compressors is that they are really quiet and if maintained well can live longer than you! They can pump at least 0.6 CFM and easily provide max. pressure of 85 PSI (what PSI and CFM means is explained in the right compressor article).
OK, they are pricey to buy but what about oil-less? Yes, there are some pros to it. They are cheaper and because they are oil-less they don’t require that much of maintenance. They are also compact. The noise can’t be compared to the industrial type of the compressor but it is not that close to oil-lubricated compressors. I would say that it is a bit louder than my PC (not usual PC :)).
What I don’t like about oil-less compressors is that it almost became essential compressor for airbrushing. The other thing is that no matter where you buy them from – US, UK, Europe… I am sure the origin is somewhere in Eastern Asia. They just put stickers over with their own home brand.
So, what to look for when choosing the best air compressor?
The most important thing is PSI and CFM.
For all of the kind of painting 30 PSI isn’t really enough because in some situations the compressor might work on the edge. That’s not good, off course, that’s why you should use compressor that has some reserves (for example max pressure from 60 to 85 PSI).
0.35 – 0.45 CFM might be enough for some spraying but quality airbrush with internal mix require at least 0.55 to 0.7 CFM, so it’s also good to have some reserves in CFM too.
More CFM means more money. The optimal configuration for average airbrush painter would be 0.6 to 0.7 CFM and 60 PSI of air pressure.
If you are in the store buying the compressor, all you need is to plug it into power, switch it on, shut the output with your finger and watch. If you don’t see any air leaks then you can pay the money for it.
That’s it about compressor as a whole piece. What about gadgets?
The compressor itself is an “idiot”. If you don’t have some additional accessories for it, it will burn or blow out.
Many diaphragm compressors have thermal-switch that protects them from overheating. In cheap compressors it used to surprise the artist. It might go on and switch the compressor off in the most important moment and sometimes your compressor might go for 4 hours without a break.
Because of that it is very useful to have a pressure switch which can be used only if you have a tank. It will provide some time off for compressor. Of course if the tank will be small the break won’t be that long, but hey, even a short break is something. I wrote couple of articles on that topic. How to make temporary pressure switch and how to set up the pressure switch for your DIY compressor. If you don’t have it then the compressor will pump the air until it will tear up the hoses or maybe blow something out. It depends what additional protection is there.
Regulator is probably the most useful thing in all that setup. Usually it has a gauge on it which is needed to set the proper pressure for certain purpose or paint used. For example if you paint a big area you can set it to 30 PSI or if you’re going to paint a tiny details you may be fine with 5 to 8 PSI using very thin paint.
I would not recommend for 100% to believe those numbers on Chinese gauges but it is not really that important in most cases, after all rough numbers are better than nothing.
All the regulators have a transparent tit on the bottom – it is moisture trap. It should catch condensed water coming from compressor and prevent spitting water from airbrush and damaging the art piece. Sometimes you may see Iwata airbrushes with their own water traps connected directly to air input.
Not all moisture traps work perfectly!
The last piece of this puzzle is tank. You may always read or hear that its main purpose is to smooth the pulsing air coming from compressor, that’s in theory, but practically pulsing air can be solved by using a 3m or longer air hose. Another use is as an air storage and time off for compressor. Well, 3-5 liters tank in some airbrush cases wouldn’t last even a minute. So for these sizes the question of air storage should be opened. On the other side many users complain when the tank is bigger because it takes a lot of time to compress all that air and then to switch the engine off.
When talking about cheap oil-less compressors the only real use for tank is that it will provide additional help for catching a condensed water – a kind of additional moisture trap.
But when we look at oil-lubricated compressors the tank is a must have because it will catch also oil.
To sum it up. My best advice is, as you can expect, to get oil-lubricated compressor. If you don’t have the money, build one or find someone who can do it for you, I’m sure it will be much cheaper than buying one. All those oil-less compressors are good only for playing but not for the real jobs.
That’s it for today. Have I forgotten something?
Please share or comment.
I wonder if it could produce a better compressor, to move the compressor intake outside the tank it is sealed in. Yes it will mean you need to cut it open, drill a hole and put a pipe outside the tank. bit there will be no oil in the intake.
Not a bad idea, have you implemented something like that or have you seen it somewhere? I’ve been thinking how to make an oil-lubricated compressor with less maintenance needed because usually from time to time I need to disconnect the tank and empty it. I’ve been thinking of making a hole at the bottom of the tank and shutting it with a bolt, something like in cars to drain oil when changing it.
I also seen one like you mentioned but it was experimental. A guy connected 0.5lt coke plastic bottle before the tank through the bottle lid and positioned it lower that tank itself. He could actually see all the oil and condensate collecting in that bottle and then just unscrewed the bottle and emptied it. But he was working with small pressures, of coarse.
Well it was the first thing I did with the one I used back in the 60’s — I used a 2 cyl. I found out after opening it. I think today’s compressors are much easier to open and if you use an angle grinder you can do it so no sparks enter the tank. True this ask some sort of workshop and a bit craftmanship but as you say worth a try. — What I found was that the air intake was just a small copper tube that ended some two inch over the bottom of the pot — guess in a closed system, it do not matter if lubricating adn freeze liquid are mixed, but I thought it to be the most important issue, to make sure the oil could not enter the intake., so after opening the compressor and putting a rubber tube on the intake I had to drill a hole for it and put the tp back on again. I agrea it never was as silent as before becaurse I had 3 bended flat steel welded on top and bottom and bolts thru to keep the top in place.Still there was an opening all way round and I didn’t find a gasked that would fit, so it had to stand on some old newspapers as the lubrication oil realy are sprayed around inside. But I think this is the best way — they do not care that oil and the freeze liquid are mixed in the closed system in fact the tank the compressor are sealed in, is a part of the design. It is important to look at how they work in a fridge.
I’ve written before something about the oil in these type of compressor here https://airbrushdoc.com/tipstricks/oil-compressor/
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