spray finishing

[michel99]

Can someone tell me what size compressor (33 or 60 gal.) I need for some semi-pro work. I don't need a constant feed but at least enough to finish the drawers then the case etc.. Thanks

[PaulMarcel]

That depends heavily on your gun. Your gun should have a pressure requirement listed and CFM at that pressure. Make sure your compressor's SCFM rating at the pressure exceeds the CFM required by the gun. The size of the tank is just a buffer and can lessen the amount of cycling the pump does.

I use an LVLP gun (a conversion HVLP that takes a lot less pressure) and it works well with my 20 gal compressor that has 7 SCFM @ 40psi (IIRC). That compressor couldn't handle most guns without excessive cycling, if at all.

Another consideration is the finish you plan on spraying. This past weekend, I sprayed GF Polycrylic on two cabinets with 3 tray drawers. Cabinets are 5' high, 3.5' wide. Polycrylic has high solids so for me to get good transfer, I needed a 2.5mm nozzle (my next smallest is 1.8mm which was too dry). I also opened up the fluid draw considerably. That said, this was probably one of the more air-hungry spray sessions I've had in awhile. My compressor kept up.

In retrospect, look around at a lot of guns especially pressure pots vs gravity feeds. If I were buying a compressor today, I'd make sure it could handle the larger SCFM requirements of a pressure pot even if my immediate plan was to use a conversion HVLP.

[michel99]

Thank you very much for the fast reply now I know that you can't take for granted everything a salesman says to sell a big expensive compressor !!!

[AceHoleInOne]

Not sure what the definition of semi pro is :)

However if your a hobby woodworker and you don't use air tools. A simple 2 cylinder pump on a 20 gal tank is good enough to spray drawers and a case, using an hvlp gravity feed spray gun. Just make sure you purchase a good line dryer to catch the water condensation and oil vapor that can collect in your air-line.

I use a 1.4 needle and nozzle in my spray guns, I have sprayed a lot of General Finishes water based topcoats without thinning the product, and have had no issue. That's just me.

-Ace-

[hhanger]

Don't overlook the virtues of a HVLP system. It will have much less overspray than a conventional gun. Mine is a bit overkill, a Fuji 4 stage, but I'm always a bit amazed about how smooth a layer it puts down. It can make anyone get professional results.

[Pete Bennett]

Hi I have had a three stage Fuji Q3 for about a year now. If the four stage is any better I'd love to know how? Fuji kit is superb. Most of my spraying is with AC laquer but I'm thinking of going over to a water base. Any one out there with experience of the differences I would sure like to hear from you please.

Pete