Tank size Matters... NOT! the untold truth.
I have seen a few threads asking if adding Tank capacity to the Air compressors will help? Adding Tank capacity is not going to make too small of a Compressor situation any better!
If the air pump itself doesn't put out the air Tools CFM requirements no amount of Tank capacity is going to make up for it!

Take my new compressor as an example it has a Very small Tank of about 50 Gallons BUT My Air pump is HUGE with the right Electric motor and the right size Pulley wheel I can have up to 50 CFM free air from my Pump alone. In its current set up I have around 30 CFM free air but still its more than enough to run any of my air tools alone all by itself with out any air tank at all. NO air tank! maybe not at the correct pressure requirements But that's another function of the air tank and Pressure control switch and pressure Regulators for another conversation.

Think of the Air tank as a Shock absorber on your car, The shock absorber is there to dampen sudden movements to the spring it doesn't help the spring rebound OR Deflect! The shock absorber absorbs and slows down the shock energy from the Pot hole or rock in the road That's all it does! It dampens and slows down the action of the spring so the Spring doesn't Jump or snap back to its at rest position whether its being compressed or deflecting.
An Air tank does the exact same thing! it Dampens the the air pressure loss from your tools usage Or the compressors pump kicking on so you don't get a sudden Pressure spike or pressure loss. You want the Pressure in your Tank to remain fairly stable and constant no matter what the demand.

Think of the Compressor pump as the Spring on your car or truck.
You need a compressor pump that is big enough that it can run any of your tools alone without the air tank, think about the spring as it is holding all the weight of the car or Truck, It doesn't need a Shock to do the job! when it is sitting still IF the Compressor pump or Spring is to small to hold the weight of the car or truck its going to Sag, If a compressor pump wont run your tools without the air Tank it sure isn't going to do it with an air Tank for very long, No matter how big the air tank is!
You will be forced to stop work as soon as you run out of available volume of air and wait for it to charge the tank back up again.

Painting with too small of a compressor is a sure way to mess up a Paint job in a hurry.
And waist expensive paint. Relying on Tank capacity is a sure way to air pressure Fluctuations and Paint job failure.

Absolutely right, Dennis. It's a combination of the two that will give you consistent pressure and volume.

I blame a lot of the misconception about compressors and just what they can "drive" on our big box hardware stores here in the US. A lot of guys that are thinking about getting into this hobby/semi-profession see these compressors in these stores, see all of the air tools around them, and just figure... "Well, I'm only going to shoot the one car so I don't need much compressor to go with those tools." I'll just get that big 26 gallon 2 h.p. rig on wheels there and go at it.....
When everything imaginable goes wrong.... they come here......

Agree with all of the above.

It seems people have a hard time comprehending that air tools have two required minimums to operate correctly, Volume (CFM/SCFM) and Pressure (PSI).

They see a 2HP compressor that puts out 120 PSI and think it will run anything. They never bother to check the volume of air the compressor is capable of maintaining.

Extra tanks will only add "stored" volume and in reality means the compressor will take about 5 seconds longer before it kicks in. When that happens they have lost and continue to lose the necessary volume of air to run the spray gun or tool because the air compressor cannot supply the necessary CFM.

I went this route when I first started and my DA would die after a minute or so, plus the spray gun would start pulsing in sync with the compressor.

'68 Coronet R/T wrote:I went this route when I first started and my DA would die after a minute or so, plus the spray gun would start pulsing in sync with the compressor.

I think a Lot of us started this way convinced we could do a paint job cheaper! and we all learned the hard way!

The Truth is Ya you can save a Lot IF you do it yourself AND have all the right tools AND all the RIGHT equipment AND SELL paint on the side! Then ya you can save a bunch!

I have to admit I tried the little compressor that Lasted me Two days! and I went out and got a Big one.