What to look for when finding a Compressor / Tank

XKCD

You’ll need some sort of air source for your airbrush, and the following will help you pick one out - there are a few options.

If you’re not planning on using the airbrush too much, just buy a tank – you can bring that to a gas station and use their machine for tires to fill it up. (I get about 3 hours give or take from an 8 gallon tank)

If you're looking at airbrushing a reasonable amount, then get a compressor with a tank attached. A small tank will do, to at least regulate the air flow and give your compressor some down time, while a tank under 10 gallons can still be affordable and give you hours of work time before needing to be refilled.

The following article is going to go into details as to why and cover some other features to look for...

Types of Air Sources

• The cheapest (upfront) is a can of air.
• Very quickly becomes the more expensive option as you use them up. Don't waste any money on these.

• Spare Tire
  wasn't aware of this until I read the LeadHead's airbrushing post
• Instead of an Air Tank, you can use a spare tire... weird, but potentially free. (Or dirt cheap from an auto wreckers)
• Badger sells their "Propel Regulator" which apparently can be a go-between.

• Air Tank
• If you're only doing the occasional work, you can get by with just an air tank.
• A friend/family member with a compressor can fill it for you.
• With the right adapter, you can also fill it yourself at the nearest gas station using the same machine for tires.

• Hobby Compressor
• Found in art, hobby and craft stores. Usually for smaller work than higher end compressors.
• Don’t always have a tank attached, (though you can always buy a separate tank)
• Doesn't get to the higher pressure ranges. Lower end ones may only be good enough for basic airbrushing with thin paints (35psi) so you may need to pay the extra money for a higher end one. (70psi)
• Usually quieter than larger compressors, but without a tank, they’ll be running constantly.
• MUCH smaller than pro compressors, if space is limited.

• Professional Compressors
• Found in hardware stores.
• Usually have a tank attached. (I get about 3+ hours out of an 8 gallon tank)
• Various attachments available for filling car tires, staple gunning, etc. 
• MUCH larger than hobby models, which could be a problem for some.
• Most expensive option, but will probably have a longer life.
• Can usually output enough pressure for multiple people to work at once.

Sourcing
I’ve said on a number of occasions that I subscribe to a certain school of thought that says buy from a hardware store instead of a hobby store whenever I can.

In addition, read my outline in a previous post entitled "Shop Smart"

• New vs Used

I don’t usually have a problem with buying used equipment if it’s the right price. An air compressor however, is something I recommend buying new.

It’s a fairly enclosed device with lots of little parts, o-rings and washers or other more complicated parts that wear out. This makes repairing them a potentially expensive endeavor. Some compressors require regular maintenance (like oil) which damages the compressor if it's overlooked. As for the air tank, you want one that can take the pressure you’ll be putting into it and don’t want something dented up. You also won’t be able to tell if the inside is rusted.

Expensive equipment is best bought new unless you find a crazy deal.

IF you do decide to buy used, don’t get something from a machine shop or a nail salon, because these will probably be well used. A hobbyist who hasn't put a lot of hours on their machine and/or has taken care of it may have a reliable device. Still don't pay too much for it since cash deals don't usually include refunds.

• Local vs Online

There are probably plenty of places in your area for find at least a professional machine. Art, hobby and craft shops won't always carry compressors, but might have a catalogue you can order from.

The problem with buying an air compressor online is the weight. This translates to high shipping costs and anything you save by buying online could be lost in shipping. If it arrives and there’s a problem with it, now you have to deal with contacting the supplier and shipping it back – and guess who’s paying the cost to ship back this heavy item?

• Price

The features you're interested in will determine the price. I recommend at least one with a tank. Est prices listed in CAN / USD. These prices are just a rough guide - they'll vary quite a bit by brand, region, online vs store front, etc.

• Hobby Compressors
• Often price will speak to quality, but it seems to be difficult to judge for these. RESEARCH your brand.
• You could be looking anywhere between $50-200 for a decent one.
• For the cost you're paying, make sure it can output enough pressure to run the airbrush you want, and plan ahead. You don't want to spend $100 now for a 30 psi compressor and have to spend another $200 later for one that can do 70 psi.
• Err on the side of a good quality one - without a tank to regulate your air flow, a sputtering engine can cause sudden bursts or drops in your paint flow.
• Hardware Store Compressors
• You can usually find these for $100-300
• BUT they often go on sale for half that. (Mine cost $150, with an 8 gallon tank and a bunch of air tools)
• Sometimes, these will come with extra attachments that you probably don't need, but will increase the cost of the unit.
• Most of the time, these have a tank to provide a reliable stream of air. (more on this later) The size of the tank will usually affect the cost of the compressor.
• Compressors with a 1-3 gallon tank could be under $100
• While in the 7-10 gallon range you're probably looking at $150-200.
• The cost of these QUICKLY jumps into the $500-1000+ range for higher end compressors with dual-piston, oiled (quieter, longer life) and much larger tanks.
• Do you pay the extra for an extended warranty?
• I did - since I found my compressor on sale, and therefor cheaper than I was expecting to spend, $50 for another year seemed reasonable.
• Kits
• You can often get kits for the mid-high end airbrushes too. They'll come with the airbrush, a compressor, a hose and perhaps some cleaning supplies or mixing jars and such.
• Pricing will vary greatly on these kits, so do a little research before investing. A kit should be roughly the cost of all the items in it, usually with a bit of a discount.
• A plus side is it's everything you need, all in one place. No hunting around.
• On the down side, they don't tend to include air tanks.

• Noise

While reading over the options and features, and deciding what compressor to buy, something to keep in mind is the amount of noise it's going to create. Family and neighbors might not be too happy if you choose something that runs 24/7 and sounds like a chainsaw. (slight exaggeration) I'll mention a few things that impact both the loudness of a compressor, (oiled vs oil-less) and how long the compressor has to run. (using a tank)

Another thing to remember is a lot of areas have laws or bylaws to regulate how much noise you can make and compressors tend to be loud enough that if there is such a law, you could be breaking it.

• Bylaws like this tend to only be enforced if someone complains. 
• Daytime hours are often regulated too, but generally nobody complains so it's not a problem.
• A poor relationship with your neighbors is more likely to cause problems.
• Your city's bylaws will state hours, noise levels (not that the average person has equipment to measure these) and even different laws for specific equipment. (such as "any noise-creating blower power fan or any internal combustion engine")
• However, cities will often have extra provisions preventing "any noise which disturbs or tends to disturb the peace and tranquillity" - which basically means it doesn't matter when and how much noise you're making, if someone complains, you can be shut down. (My city even lists that singing isn't allowed to cross property lines)
• Fines
• Noise violation fines could be anywhere from $50-200+, or just a warning.
• If you talk back to the bylaw officer, use foul language, get complained about multiple times or from multiple people, you're more likely to get a higher fine.
• Some examples:
• Daytime
• Compressors usually won't make enough noise to cause a problem.
• Unless a neighbor works nights and sleeps during the day or is noise sensitive. (migraines)
• Evenings get a little tricky.
• Most people won't care if you're running a compressor from 8 to 10p.
• If you have a family with young children next door, 7p might be the latest you can work without complaint. (another reason for buying a compressor with an air tank)
• Mornings
  (FYI, it's bad for air tanks to leave them full when not in use, so while you could fill a tank before bed, it's not a good idea)
• Most people are up by 7 or 8a.
• But families might have other members such as children who sleep in.
• Start later on weekends.

If you don't think someone will shut you down for using a compressor, I've seen bylaw officers shutdown a Relay for Life (cancer) Fundraiser.

Features

(Not to be confused with in-line devices, which I'll cover in a later post)

• Pressure

Airbrush equipment is usually measured in Pounds Per Square Inch... or P.S.I. (Sometimes as kilograms per centimeter squared) 35 psi tends to be the minimum for airbrushes, up to around 60 psi. Larger compressors could go up to 150 psi or more because there are tools that use high-pressure air instead of electricity.

Always check what the maximum pressure ratings are on equipment so that you don't damage anything. Don't run equipment at a higher psi than it's rated for, or you could blow valves, tubing or even cause explosions.

• Compressor

The compressor

A compressor is a small engine that sucks air in one side (usually through an air filter so that dust and dirt doesn't jam it) and blows it out the other end. They vary in strength from smaller hobby ones (35-70 psi) and go up to higher end models (100+ psi) for heavier duty tool use.

A compressor connects to either an airbrush or a tank and often compressors and tanks are built together as one.

Compressors will have regulators on the output to control the strength of the pressure. While a regulator will prevent air from spiking above your set output, a compressor can sputter and/or hiccup causing the pressure to drop.

• Air Tank

While a regulator should prevent a spike in air pressure, it won’t prevent a drop. Uneven air means bursts of coarse mist and spotting. Air tanks prevent drops and create an even flow of air.

The air tank.

Get a tank. Period. First, you don’t want the noise of a compressor running for hours while you work. (and neither do your family, friends and neighbours) You can’t restrict airflow by putting a box around the compressor either, this can damage it. So, you make some noise and run the compressor for a few minutes to fill the tank, and then the airbrush runs off a constant pressure from the tank that won’t spike or dip. A tank can be filled up outside and brought inside to work.

Most compressors with tanks are a whole unit, but you can find separate tanks. This allows you to work from the tank and store the compressor somewhere else, perhaps where the noise of a compressor is less of an issue. (like a garage) You can also bring this tank to a gas station and fill it with their air machine.

I got an incredible deal on a compressor with an 8 gallon tank, which lasts for many hours. When working late, I’ll take 2-3 minutes to fill it up at 9.30p and work until midnight or 1a. Usually I see small tanks, about 2 gallons – so a little under an hour of work time and an even air flow, which is still a reasonable amount of time to work without a compressor screaming in your ear.

• Pressure Gauges

A compressor will have a maximum pressure that it can output. You want to make sure that its max can cover the range the airbrush requires to work – which won’t be a problem if you get a compressor from a hardware store.

You also want to make sure that you can adjust the valve and gauge to levels for your airbrush. The gauge is a circular meter with a needle that points at the pressure the compressor/tank is set to and you use the valve to adjust this. I’m going to use a clock analogy here:

Adjusting to 4 kg/cm^2 wouldn't be too hard.
Adjusting to 58 psi is a little trickier.

• Take a clock the size of a wrist watch, numbered 1-12.
• It’s really easy to read the numbers, so when you’re setting the clock, you don’t have any problems lining up the hands where they need to be.
• A compressor’s gauge will usually be a little larger than a wrist watch.
• What if that clock went up to 35?
• A basic hobby compressor might go up to 35psi.
• Think about how small the numbers would be and how much harder to read they would be.
• A higher end hobby compressor could go up to 70psi
• That’s a lot of numbers.
• My compressor goes up to 150psi, and the meter goes up to 270psi.

The point of what I’m saying here is make sure the gauge is physically large enough to read the numbers and the scale isn’t so large that you can’t adjust for the smaller psi range that airbrushes require. A gauge with a full-scale from 0-30 for example would be much easier to read than one like mine pictured above where 0-30 is just a fraction of the whole thing. Don't get me wrong, I'm not complaining or saying my gauge is hard to read, especially since you also usually only have to be accurate to the 10’s and 5’s psi. I'm just suggesting you make sure that YOU will be able to read whatever gauges are on the equipment you buy.

• Auto-Fill

For compressors with an attached tank, they usually keep your tank topped up as you use up the air. For example, if I leave my compressor turned on, it’ll fill up to 150psi then turn off – as I use it and the tank hits 100psi, the compressor turns on again and fills the tank back up.

I swear I jump every time I’m airbrushing away, totally in my zone and dead to the world… when suddenly the compressor’s engine roars to life like an Ork screaming “WAAAGGGGGHHHH!!!” in my ear. For this reason, I fill the tank then turn the compressor off. (The tank is sealed at the compressor, so turning it off won’t cause the tank to empty) You do need to keep an eye on your gauge, because once the tank pressure sinks below the pressure your gauge is set to, then your airbrush will only work at the tank's pressure.

So I suggest you fill the tank, then turn the compressor off. When you have a moment, just turn the compressor on again and stretch your legs while the tank fills back up.

• Oil vs Oil-less

An oil-less compressor is easier to maintain in the long run, because there is no maintenance. They also tend to be cheaper than oiled compressors. You need to keep an eye on a compressor that takes oil and regularly replace it. If you haven’t used the compressor for a while, it’ll also have to be replaced.

What’s the difference? Oil lubricates compressors to keep them running smoothly – that doesn’t mean oil-less compressors are going to break down; it literally means an oiled compressor will run smoothly… see: QUIETLY. Most compressors I see are oil-less, which are cheaper but louder. (another reason I like having a tank that I can quickly fill, then work in silence for hours)

• Run Time

Some compressor engines can only run so long before it has to rest. They’ll automatically shut off so nothing overheats. It’s good to know how long you can run the compressor in a sitting, AND how long it has to rest (it's cool-down period) before you can work again.

Once again, another reason to have a tank, so your compressor gets some down time.

• Tubing

You’ll be working from an airbrush hose, which connects easily to a small hobby compressor. A larger compressor usually has a thicker plastic hose that doesn’t bend too well – use an adapter to connect your flexible airbrush hose to the air compressor. You can get a quick release valve if you plan on using the compressor for other things.

With a long enough tube, you can hide the compressor away in another room or a garage. However you will lose pressure over a longer distance, so you may have to turn the pressure up a little OR turn it up a lot and put another pressure regulator (valve w/ gauge) in the room you’re working in. (more on this later)

Compressor tubing will usually have a visible pressure rating on it, which should be higher than the pressure the compressor can output. You may not want to use a hose from one compressor on another - for example, a lower end hobby compressor's hose might be good for up to 50 psi, while a larger compressor's hose could be good up to 200 psi.


Read Instructions

Once again, read the instruction manual! As a heavier duty power tool or an intricate hobby model, there are a few things to keep track of to make sure you use and maintain it properly.

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Take a look at the Wargaming Tradecraft Techniques Page for links to the entire Airbrushing series and other tips, tutorials and information.

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