Air Compressor Requirements For Painting A Car

There is nothing like a fresh coat of paint to refresh your car. Any shade tree mechanic can swap out engine parts and improve the car’s performance. But it takes a next level technician to master the art of painting a car.

2015 mustang

If you’re looking to enter the auto body repair or automotive painting world you’ve undoubtedly uncovered your need for an air compressor.

Some brief poking around probably points you towards a 60-gallon air compressor. However, 60-gallon air compressors require 220V of power. Industrial air compressors – like these compressors on – can be a pain to setup, with added circuits often needed to support the power draw.

So what is the smallest compressor that a beginner auto body repair technician can get away with?

The challenge with a small air compressor is that you lack the air volume you need to get a consistent layer of paint over the entire car. If you’re working with a smaller tank – say about 20 to 30 gallons – you don’t have enough air to complete the paint without waiting for the compressor to recharge.

As the air pressure drops, it can create erratic spray patterns and ruin the paint job.

I smaller air tank is also going to have greater condensation problems. All air tanks have some water problems: the humidity in the air collects in the bottom of the tank.

However, because the smaller tanks run hotter, they tend to condense even more air, forcing you to drain the tank more frequently.

You will also want to run a dryer on your airline to help remove water and keep it from entering your paint stream.

If you are insistent on painting your car with a smaller air compressor, you should consider using a low-volume-high-pressure spray gun (or HVLP gun).

Low-volume-high-pressure spray guns are preferred in the industry for laying down the clearcoat, and most people don’t think of them as usable for painting. However, they work equally well for the painting portion.

Because they require a lower volume of air – typically in the 3 CFM range – you can get away with a smaller air compressor tank than the standard high-volume spray guns require.

Even with an LVHP gun, something like a pancake compressor that only has 3 to 5 gallons is too small to use. You are still going to want closer to 20 gallons to ensure consistent airflow. I’ve seen some folks claim that you can do it with as little as an 8-gallon unit, but I have my doubts.

The real challenge in painting with a smaller tank comes when you are laying down the clearcoat. If part of the clearcoat dries before you lay down the next pass, the overspray onto the dry portion will leave it with a dull look. This dullness will require more post-painting, buffing, and finishing to bring up the shine.

If you have the money, shop space, and electrical outlets, the ideal compressor is going to deliver 14 CFM or better at 90 psi. Now, there are even some 60-gallon compressors that don’t meet this requirement for air flow so you will want to pay close attention to the specifications to make sure you get the right one.

Now, it might also be worthwhile to discuss the heresy of painting your car with rattle cans. I mean if compressors are so expensive, how about giving it a quick rattle?

Rattle can work is great for small spots. For example, my Honda minivan has a wonderful rust spot by the passenger side sliding door.  I’m sanding it down, applying Bondo and prepping the surface for a quick rattle.

Using the VIN number under the hood, I’ve been able to source what is supposedly an ideal paint match.

For my aerosol can, I’ve purchased a little adapter that connects to the nozzle and gives me a handle to hold. This enables me to have more control and delivers a more consistent spray pattern.

We’re going to start with a hit of primer to make sure that there is a good surface for the paint to bond with, and then I’ll give it a light sanding and tack cloth.

It will then get three coats of paint with 30 minutes of dry time and a bit of tack cloth between each coat. Finally, an hour after the last layer, I’ll hit it with some clear coat.

With any luck, in the next couple of weeks, that rust spot will be gone and, more importantly, will no longer be able to spread and eat a hole in the side of my car.  It’s an easy way to spend a few weekends and doesn’t require that I invest in a compressor and all of the spraying equipment.

However, there is no way that you could talk me into doing more than maybe a door or a quarter panel with the spray can method.

But for those of you with a small tuner car that just want it to look fresh, and reflect all of the upgrades you’ve put into the engine, learning to paint your own vehicle is a great step and a money-making skillset.

The other thing to look at is an LED paint light to make sure you have consistent lighting. If you are working in your shop, you aren’t going to have enough light to ensure that you are avoiding runs.

Like we’ve discussed, you can somewhat cheat the system and get away with a smaller-than-normal air compressor, but it is tough to cheat on the lighting. Lights don’t have to be the most expensive ones, but you’ll want to make sure to set up plenty of light.

The bottom line is, don’t let me scare you.

Get your LVHP gun, and an affordable air compressor to start practicing. If you are serious about learning how to paint, I’d suggest investing a junker off of Craigslist and dig into how to fill holes, pull out dents and lay down a solid layer of paint.

Then, as your skills progress, you can move on up to the big leagues with all the pricey equipment!

Hope to see you on the streets with your shiny rig.


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