Mixing/spraying paint

[Code54]

I recently purchased a HVLP spray gun, inline filter, gun water filter and all the little things to attempt to learn to paint. What I am not too sure of is how do I learn the proper way to thin paint to spray it. I was playing around tonight and thinned the paint (Valsar tractor and implement paint) 1:8 as the can said. What I noticed is it seemed very thin and the gun was surging when I was painting so I know it was not correct. Is there a standard mix out there and/or a mixing chart somewhere? Also what causes the gun to surge (sprayed fine but would spray, pause, spray, pause, etc...)
Thanks and any info on spraying paint is helpful because I know absolutely nothing.
Oh the compressor is an IR 80 Gal, 2 stage, 24 CFM, so air flow should not be an issue (at least I think....)

 

[JimRB]

You mean 8 ounces of naptha for a gallon of paint and some hardener?

 

[JimRB]

Follow up. A few years ago I mixed some Valspar implement paint according to the directions on the label and used a cheap gravity feed HVLP spray gun. It sprayed nicely. I do not have any empty or partial cans to read the mixing instructions. I used a much smaller compressor. A 20 gallon tank or so Binks pump.

Here is an article that is interesting. Good Stuff! | Amateur radio - Teardrop trailers, Vintage Shastas, Martin Luther Miller, TN and more

 

[JimRB]

Another follow up. You can get mixing cups that have the mixing ration on the side. You dump so much color in, add the thinner and then some catalyst. Paint Mixing Cup Set 13 pc
Video that explains the mixing cup
[ame=http://www.youtube.com/watch?v=nbywJIEYNfQ]Auto Painting : How to Mix Auto Paint - YouTube[/ame]

 

[ETpilot]

For mixing paints you need to follow the manufacturers recommendation. It will be on the can. Different paint systems mix in different quantities. Some just add thinner, others add thinner and hardener. I mix an aircraft paint, 3 parts, by weight in grams.

As for the spray gun surging, that is usually an air leak in the gun. Most often it is the fluid nozzle that is not tight enough. Look at your gun manual. It may list a torque value for the fluid nozzle. The fluid nozzle must have a good seal. Also the packing for the needle and air valve need to seal. Usually you add a little oil to the packing. Again check the gun manual.

After use do a thorough cleaning of the gun.

 

[murphy1244]

After use do a thorough cleaning of the gun.------He ain't kidding about that.
If your pulsating you have a air leak. I shoot at around 40psi with my devilbliss.

 

[Rustywreck]

It has been awhile, decades in fact, but when painting cars I used a viscosity cup. The paint can had a viscosity number on it and you used a viscosity cup to measure if additional thickening or thinning was needed.
I haven't looked at an automotive paint can in a long time so I don't know if that system is still used - it worked pretty well.

 

[flusher]

It has been awhile, decades in fact, but when painting cars I used a viscosity cup. The paint can had a viscosity number on it and you used a viscosity cup to measure if additional thickening or thinning was needed.
I haven't looked at an automotive paint can in a long time so I don't know if that system is still used - it worked pretty well.

A VC came with the Harbor Freight HVLP gun I use to paint my old, restored tractors.

 

[Code54]

Great information, thank you.
As for the gun, it is from about 1991, and had not been used since then so the idea of an air leak sounds spot on. I also have a brand new gun but did not have the fittings on it yet so I figured I would use the old one - guess I better get the new one out and start practicing mixing paint.

 

[woodlandfarms]

One additional question. Do you need to put any sort of dryer or something like that on your tank line? Or is paint now pretty much immune to those issues?

If so, what kind of drier are people using. Again, I am keeping this in the vein of tractor painting, not precision auto.

Carl