Why doesn't my HF siphon feed gun like latex?

[dbhost]

Okay this is giving me fits. I have 2 guns, a Husky Pro Multipurpose Siphon Feed or Pressure Feed Spray Gun model HDS50099AV, and a Central Pnuematic 32 oz. Automotive/Industrial Air Paint Spray Gun with Internal Mix Nozzle item #91011.

I bought the Central Pneumatic mostly because I was paranoid about ruining the Husky while I learned to spray.

I have been able to use both. So far I have run Duplicolor "Paint Shop" automotive primer and paint through it (color match painting the toolbox to match my truck), oil based household paint, lacquer, and latex house paint...

Both guns spray great. The Central Pneumatic is actually quite a bit easier to clean after use, but I have one problem with the CP that is REALLY bothering me...

The Central Pnuematic gun does NOT like to spray latex paints...

I reduce the latex down with Floetrol and mix it well until it flows easily through a paint strainer funnel, not as thin as I have seen some guys on Youtube spraying latex, probably about 1 cup floetrol to 1 gallon paint. The Husky sprays it perfectly. A borrowed HF HVLP gun, I think item #47016 sprays it perfectly, but my neighbor wanted his gun back... But my 91011 just does NOT want to spray this stuff. It spits out of the gun like the orafice is jammed, but it's perfectly clear...

I am afraid to reduce the paint any further, but I need to get this process down. I have ceiling corners that I need to get painted, and follow that up with the cabinets for the shop I am building will need paint. You may recall I have started painting my shop cabs to reduce the darkening effect the plywood cabs was starting to have in my shop...

Is this gun just not a friend of latex? Do I run the risk of ruining my Husky with the stuff?

So far the gun that sprays it best is that little purple HF HVLP gun. Would I be best off just grabbing one, okay a couple of those and flogging the snot out of them? I need fast coverage of LARGE areas, and I want something MUCH easier on the back than a roller on an extension pole.... If I could get this thing to spray, I would be way ahead of the game...

[cabinetman]

You might need a larger tip, or a needle and tip. Some guns you might need to change air cap too.

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[dbhost]

This gun lists a 1.7mm needle. The HVLP that I borrowed that sprays this fine has a 1.5mm needle. The Husky has an assortment of needles. The one I have used with Latex is 2.0mm.

I need to configure the Husky for pressure feed operation and see if I can get it to work at odd angles. I am trying to spray up into hard to reach corners, chances are those areas are going to need to get hit with a brush...

[woodturner]

But my 91011 just does NOT want to spray this stuff. It spits out of the gun like the orafice is jammed, but it's perfectly clear...

A couple of things to check:

1. Air pressure and volume. The specs say it wants 1.5 cfm @ 30 psi, but should be run at 50 psi. Make sure you are really at 50 psi and that your air compressor is rated for 2 psi or so at that pressure.

2. The nozzle may not be finished to the same degree as the other guns, so that it is cavitating when latex is used. The finish could have corroded a bit inside the nozzle, etc., several possibilities. Not sure how you could check this, but you can fix it, if present, by carefully broaching the opening with a reamer. I would use a reamer 0.001" larger than the stated nozzle size. The reamer can also be used to clean the nozzle after use, to make sure it is really clean.

[cabinetman]

But my 91011 just does NOT want to spray this stuff. It spits out of the gun like the orafice is jammed, but it's perfectly clear...

They are two different guns. That one should spray the latex fine considering you thinned it. Try just plain water for a test. The HVLP works off high pressure to the gun, but lower output pressure from the gun. The CFM output @ 30 PSI, would be less at higher PSI. Specs say 1.5 CFM @ 30 PSI, @ 50 PSI it wouldn't be in PSI's but in CFM's.

You can adjust the feed and air for spitting, or too much fluid, by turning down the fluid knob. Or, starting lower on the fluid knob adjustment and increasing the air mix. You should see a difference in the atomization.

.

[JimD]

I almost bought a bigger nozzle set for my Fuji before trying flotrol but that solved my issue with a heavy primer from Hood finishing (a very nice stain hiding fast drying primer). I haven't tried it on latex yet. I got it to spray without the flotrol but I had to adjust the material delivery setting (screw on the back of the Fuji gun) to a more open position to get atomization and it was still not so good. With flotrol it sprayed well.

I've also read that stainless likes latex based finishes more than aluminum. I'm pretty sure the HF is aluminum but what about your other gun? I use my Fuji exclusively now. It is blower system and works much nicer than my Wagner.

Jim