If your just getting started and considering spraying paint whether it be to spray a car, wood work, or something else one critical expense to start is a proper air compressor. This article will cover the best types of air compressors for painting & painting cars, what your air compressor will require to be able to paint cars, and things to consider when choosing an air compressor for painting.
Number 1 Factor in Choosing an Air Compressor for Painting – Air Compressor CFM
Spraying paint with an air spray gun requires a large volume of air being injected into the paint which creates atomization or break up of paint. Volume is referred to as SCFM or CFM on a compressor. Often people can confuse PSI and think that PSI is what determines paint break up. PSI refers to the pressure that an air compressor provides. When it comes to spray guns and air compressors for painting, the cubic feet per minute is the critical factor to consider, it is also what you typically pay for most when buying an air compressor.
For a quality HVLP Spray Gun you can often need up to 20 CFM of air. If you are using a Conventional Spray Gun you may not need as much air as HVLP requires a High Volume of air (HV) especially compared to conventional spray guns, but a conventional spray gun can still use 10 – 15 CFM. While there are options available for low CFM spray guns, they will typically not provide as good of paint break up which can effect your finish quality.
Number 2 Factor in Choosing an Air Compressor for Painting – Compressor Type
In order to be able to deliver sufficient CFM for painting, you will typically need a 2 stage compressor. A 2 stage compressor will provide approximately 4 CFM of air per horse power of the compressor. In comparison a Single stage compressor (which is what most compressor you will find at hardware stores are) only delivers about 1 CFM per horse power. So if you will be using your air compressor for painting or painting cars, you will want to consider a 2 stage compressor with atleast 5 Horse power to properly provide air to your spray gun.
In addition to selecting a 2 stage compressor, you will also be able to choose between different compressor types depending on the size of compressor. Common 2 stage compressor designs include rotary screw compressors and reciprocating compressors.
Rotary Screw Air Compressors require less maintenance in comparison to reciprocating air compressors. However they are not as efficient (meaning they do not deliver quite as much CFM per horse power). Rotary Screw Compressors maintenance will typically involve oil, oil filter, and oil/ air separator changes. In comparison a reciprocating compressor will require more frequent and extensive maintenance including maintenance items like valves and pistons. However they often provide a longer overall life of use and deliver a bit more air per horsepower. Reciprocating air compressors do have a higher initial cost when considering a larger (above 30 HP) unit compared to rotary screw compressors. If you are selecting a reciprocating compressor for painting they will also offer an option for oil or non lubricated. If it is not allowed to have any oil in your compressed air the non lubricated compressor may be right (though it is a bit more expensive). For smaller compressors (less than 30 HP) reciprocating compressors are often more affordable. Additionally they do not produce as much heat and are cooled by air at lower horse powers. This often makes reciprocating air compressors an ideal choice when you are considering a lower horse power air compressor (which you will probably be considering if your looking for a compressor to get started painting).
Number 3 Factor to Consider when Choosing an Air Compressor for Painting – Additional Options
Once you have made sure to select a proper sized air compressor for painting the next thing to consider is if you are interested in additional options. One potential issue with using a compressor for painting is moisture and oil in your air. Having either in your air line can cause fish eyes or moisture pockets in your paint finish. To address issues like these you can consider a 2 or 3 stage air dryer that is connected to pipe that runs through your shop. However you may also want to consider an optional upgrade like a refrigerant dryer for your air compressor. A refrigerant dryer will rapidly cool and then rewarm the air as it leaves your compressor which will eliminate moisture in your compressed air line. This can be particularly important if you will be using your compressor in a small shop and not have a sufficient length of piping to allow your compressed air to travel before a 2 or 3 stage filter would be connected. If the compressed air doesn’t have a sufficient length of line to travel before reaching a regular air filter you will find your air filter will not be able to properly remove moisture from your compressed air line fast enough.
Ultimately choosing the right air compressor for painting is critical to ensure you provide sufficient air volume to your spray gun to be able to adequately atomize your paint. By having sufficient air volume and choosing a compressor that has any additional options you may want to consider like a refrigerant dryer to remove moisture you can achieve the best results possible in your painting.