HVLP needle/cup sizing and other details

[Carlos Alvarez]

Right, I guess the line to be drawn is "painting small stuff" which they say is fine, and "painting walls." I believe I'm painting small stuff, no? The biggest thing I'd do is that shed. Otherwise it will be trim and such, or small areas.

[Patrick Chase]

Right, I guess the line to be drawn is "painting small stuff" which they say is fine, and "painting walls." I believe I'm painting small stuff, no? The biggest thing I'd do is that shed. Otherwise it will be trim and such, or small areas.

The shed is in between IMO :-).

Seriously, the bottom line that everybody is telling you is that you can make it work with enough thinning and patience. I would recommend sticking with Fuji's recommended nozzle size, which will give you reasonably good atomization at the cost of lower speed.

[Carlos Alvarez]

LOL, fair enough. The dust collector shed will be my practice with this gun. It has almost zero impact, because it's in a place that will never be seen. I'll get the larger n/n set for latex on trim and for the shed. Thanks everyone.

[Curt Harms]

There's really no substitute for experimenting. I thin more than recommended but it seems to cover okay and I coat with unthinned or lightly thinned water based Poly for additional protection. I've never sprayed walls, just trim and small utility cabinet type stuff.

[Rob Young]

Only a small cheap detail gun. I also don't have enough hose to reach some of the areas to paint, and the compressor is a floor-mounted monster.

I guess what's emerging here is that Fuji basically lied about it being reasonable to spray latex?



Sorry, I'm not understanding how this is different from how the included viscosity cup works?

Wasn't sure your kit came with a #4 cup or not. Use what it came with.

[Julie Moriarty]

So I guess what I'm saying is that I *will* be using this gun for it, and what is the best choice of cup and needle?

When I need to know what air cap will be needed for a particular finish, I try the website of the finish manufacturer first. General Finishes is great for this. I have a Fuji HVLP with an XPC gun and downloaded all their info on the specifics of air caps for the XPC. With that information in hand, the right air cap size is a no brainer.

If the paint manufacturer doesn't have spraying information, maybe you can find a website that has a product with a similar viscosity and go from there.

[Patrick Chase]

When I need to know what air cap will be needed for a particular finish, I try the website of the finish manufacturer first. General Finishes is great for this. I have a Fuji HVLP with an XPC gun and downloaded all their info on the specifics of air caps for the XPC. With that information in hand, the right air cap size is a no brainer.

If the paint manufacturer doesn't have spraying information, maybe you can find a website that has a product with a similar viscosity and go from there.

Fuji provides viscosity-based guidelines as well in their manuals, though they're generic for each gun so you have to scale a bit based on your turbine. Jeff Jewitt also has pretty good guidelines on his site (at the end of the doc). One thing I like about his is that he addresses pressure-assisted guns (like your XPC and the OP's Semi-Pro) as a separate category. They really do behave a LOT differently than unassisted gravity or siphon guns as in most conversion setups.

One gotcha with viscosity-based guidelines is that because they're generic they don't take individual finishes' flow-out characteristics into account. A finish that self-levels after spraying can tolerate worse atomization (and therefore higher viscosity with any given setup) than one that doesn't. The guidelines typically assume that the finish has to be flat "as sprayed", so they often end up being conservative.

To the OP: Jeff Jewitt's doc (linked above) is directly relevant to your situation. Your gun falls into his "pressure-fed" category. At 5 psi it's on the weak end of HVLP, so you'd probably want to skew towards the low end of his ranges.

[Carlos Alvarez]

That was very useful also, thanks.

[Curt Harms]

Interesting. The Earlex 5000 is a 2-stage ~5 psi design like the Fuji Semi-Pro2, but IIRC the Fuji uses a larger, higher-power turbine (1400W vs 600W spec). The Fuji will likely require roughly the same amount of thinning, but it may be able to go a bit faster if the increased power translates to more cfm.

To the OP: Of all of the feedback here including mine, Curt's is most relevant to your situation. He's right on about the pressurized cup, which both the Earlex and your Fuji have. A 5 psi gun without pressure feed would be a lost cause for Latex.

Curt, how much do you need to dilute with your Earlex (and which brand/paint?)

Brand was whatever was on the shelf, I don't recall. As for how much, I'd estimate 15% - 20% with floetrol and a little distilled water. I know the maximum recommended dilution is 10% but the higher dilution seems to be holding up. It did turn out quite flat but it was overcoated with a water based poly that didn't need much dilution and brought back some gloss.