Teach me about Spray guns

[Rick Fisher]

I have a spray gun which I bought at the AWFS woodworking show. Another member here told me it was good, so I figured.. eh..

Its a CA Technologies CAT gun with a 3M PPS Gravity cup ..

Can I spray paint with that gun ? I know it will spray lacquer ...

I'm building and want to spray some paint.. Not huge amounts, some shutters, stuff like that ..

I get the feeling that gun won't work .. what will work ?

[Wayne Lomman]

Rick, any spray gun will spray paint as well as lacquer - the limitations are more to do with the viscosity of the coating. I take it the paint you want to spray will be the average water borne paint for exterior residential building work. If this is the case, then you are correct, the gun you have purchased is not ideal for the job. It is really a fine finishing gun.

The average house paint is really designed to be applied by brush and/or roller or else with airless spray. However, you may get away with it if you:

1. Either have or can get hold of a 1.9mm nozzle and air cap for the gun - it is available with some of the kits so you may have it or at worst, order a replacement part in that size

2. Thin the paint a bit more than usual - experimentation required here

3. Open up the fluid control as far as possible

4. Adjust the fan and air flow controls until you get the best combination you can.

Thinning the paint means you will need to apply more coats to get the thickness you need so that the paint protects as is intended.

There are plenty of options if you want to throw money at it - I don't do that but if your budget can stand it, a pressure pot set up is fairly cheap and simple and can deal with delivering high viscosity products. The CA Tech H2O CPR kit is an example of this. I would expect one of these CA Tech ones to cost an arm and a leg, but here in Australia you can get Chinese ones that work OK for about AU$100. The gun will be fairly crude but it will handle the painting and leave your finishing gun for lacquer or fine high gloss work. Cheers!

[Larry Edgerton]

Rick, I used to use High dollar Devilbus and Sata guns, but the rebuild kits cost twice what a cheap set of guns cost. I buy the cheap ones at Car Quest, 99$ for a set of two, one primer one finish. The primer gun is good for thicker viscosity paints and varnishes, the finish gun for lacquers and other thin finishes. When they start messing up I throw them away and buy a new set.

If I was going to be spraying the same finishes all the time I would invest in an airless finish setup, but I don't. I am always doing something differernt. My buddy that make Rittenhouse furniture uses one and it is awesome, but he uses that same finish all the time.

[Curt Harms]

Rick, any spray gun will spray paint as well as lacquer - the limitations are more to do with the viscosity of the coating. I take it the paint you want to spray will be the average water borne paint for exterior residential building work. If this is the case, then you are correct, the gun you have purchased is not ideal for the job. It is really a fine finishing gun.

The average house paint is really designed to be applied by brush and/or roller or else with airless spray. However, you may get away with it if you:

1. Either have or can get hold of a 1.9mm nozzle and air cap for the gun - it is available with some of the kits so you may have it or at worst, order a replacement part in that size

2. Thin the paint a bit more than usual - experimentation required here

3. Open up the fluid control as far as possible

4. Adjust the fan and air flow controls until you get the best combination you can.

Thinning the paint means you will need to apply more coats to get the thickness you need so that the paint protects as is intended.

There are plenty of options if you want to throw money at it - I don't do that but if your budget can stand it, a pressure pot set up is fairly cheap and simple and can deal with delivering high viscosity products. The CA Tech H2O CPR kit is an example of this. I would expect one of these CA Tech ones to cost an arm and a leg, but here in Australia you can get Chinese ones that work OK for about AU$100. The gun will be fairly crude but it will handle the painting and leave your finishing gun for lacquer or fine high gloss work. Cheers!

I agree with Wayne. You may need to thin paint more than recommended though. How much thinning is too much? I'm sure it depends on the formulation but I've heard 10%. I have an Earlex HVLP setup with 2 tips, 1.5 mm & 2 mm. I use the larger tip - have considered the 2.5 mm - and adjust the fluid control as required. I use a combination of distilled water & Floetrol to thin and haven't had an adhesion problem so far. An airless sprayer is the correct sprayer for paint but it's hard for me to justify the $$ for very occasional use on small items plus airless cleanup is more involved. My oldest sprayed outdoor project is a flower trellis made of SPF 2X3s and sprayed with acrylic enamel. It's been probably 5 years and still looks like new. Spraying a diluted coating requires more coats but given reasonable drying conditions a sprayed coat will be dry to the touch in about an hour (or less) so it's easy to apply multiple coats per day.

[Rick Fisher]

Thanks for the feeback. Great Info ..

I might just buy an Earlex 5500 for paint.

[Rick Fisher]

I wonder.. How does an Airless compare to air for clear finishes ? Laquer ..etc.

[Curt Harms]

Thanks for the feeback. Great Info ..

I might just buy an Earlex 5500 for paint.


Couple things to be aware of with the Earlex. One is that it's a two stage turbine so not a lot of pressure - 2 psi sticks in my mind. The cup is pressurized which helps with more viscous materials. There is no fan width control like on conversion guns and higher end turbine HVLP. Fan width is controlled by how far you hold the gun from the work. That took some getting used to when spraying narrow pieces such as rails & stiles. Hold the gun closer and reduce the fluid flow. A simple trick but one I found useful was to put a mark on the fluid control knob. It's difficult to know how much I moved it otherwise.

One thing I had a hard time wrapping my mind around was given how much air comes out of the gun how little overspray there is. I sprayed a couple doors in a closed garage and except for some drips on the floor - which were operator error - there was no evidence of paint on any uncovered surfaces.

[Wayne Lomman]

Rick, an small air assisted airless is good for clear lacquers. I can't comment on HVLP. They are not a big thing in Australia. Cheers