I'm spraying water base pigmented lacquer using a 4 stage turbine HVLP Fuji Q4. I would like to achieve something smoother and I'm thinking of buying a low volume, low pressure gun. Can somebody tell me how they're different from HVLP gun in terms of performance? I have a small shop.
From contributor J:
In my opinion, HVLP or LVLP are good for applying stains and toners, but are not very good for applying heavy body finishes. There is nothing as good as an air-assisted airless.
However, more air will help break up your paint particle, thus creating better atomization. So by using less air like a LVLP, you may not get as much particle breakup and your speed will be reduced, but your overspray will be reduced.
My personal favorite for the coating you're describing would be an Airmix gun. It uses medium fluid pressures (like 300psi to 500psi) instead of 20psi or 30psi like HVLP. Then it uses about 10 or 12 psi of atomizing air with only 3 or 4 CFM to further break up the fan pattern. This type of system offers you the speed of an airless with the control of an HVLP, but has better transfer efficiency than both. They are a lot more money than an HVLP or a LVLP, but I think you would like the results far better, if it's in your budget.
Comment from contributor S:
I'd like to clarify a few points contributor T made. Specifically, it's the psi more than the cfm that creates atomization. This is why you are having difficulty breaking up the higher viscosity materials with your turbine HVLP; just not enough pressure. Some LVLP guns (the Iwata LPH50, for example) operate on as little as 1.8 cfm, yet still produce a highly atomized finish with properly reduced materials. Even some of the more production models operate on less than 10 cfm but at a psi nearing 30.
One more comment to eliminate confusion is that the AirMix gun recommended is an air-assisted airless gun, not an HV or LVLP. An airless tip combined with an air cap produces a very nice finish at higher production rates. There are some decent portable models made by Graco and Titan, but be sure to specify you want the AAF or AAM tips. Do not use RACX system tips, they do not produce as nice a finish and do not allow for fan width adjustment.