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Poor Atomization from HVLP turbine

robert Member

I am attempting to spray ML Campbell Clawlock and Resistant. I have had to thin both far greater than I would like to in order to achieve a fine mist. Usually, it's something like 9 sec. with a Ford #4 before the finish starts to level out nicely. Otherwise, I have a pebbly surface.

I am spraying with a 1.5 mm nozzle and air cap in a Fuji bottom feed gun with Fuji Q3 Gold turbine. According to some guidelines I've found online I should be able to get good results with this setup only thinning to 18-20 seconds with a Ford #4 viscosity cup.

Is it possible that the turbine is simply not providing enough pressure to the gun, or a leak somewhere in the hose? Something else I'm not considering? Much thanks in advance.

3/9/15       #2: Poor Atomization from HVLP turbine ...

I'm not familiar with this particular gun, but with mine, the #1 problem is the vent at the top of the cup getting clogged.

3/10/15       #3: Poor Atomization from HVLP turbine ...

Turbines are notoriously weak and slow. Clawlock is thick with very high solids. One thing that would help to a small degree is to heat the finish container in hot water reducing the viscosity.

3/10/15       #4: Poor Atomization from HVLP turbine ...
robert Member

Yeah I can definitely see how thick the material is in the can, but having to thin it almost 75% seems crazy.

I'm beginning to understand the drawbacks of HVLP. What I don't get is that if one of the main benefits of HVLP is less overspray, and thus less material going into the environment, you're defeating the purpose if you have to add twice as much solvent compared to a compressor driven gun.

I'm wondering if I need to look into spraying from a pressure pot so that at least the cup itself is pressurized by our compressor, and maybe I'll get more air at the gun that way.

3/10/15       #5: Poor Atomization from HVLP turbine ...
herb johnson

sorry you r have trouble spraying clawlock with your system

the turbine does not sufficient energy to break apart a higher solids mdf primer

you need at minimum a pressure tank, even better if you have the bucks for an air assist unit

the turbine is not meant for a primer like clawlock

good luck

herb j

3/10/15       #6: Poor Atomization from HVLP turbine ...
Leo G

1.5mm tip is to small. Bring it up to a 1.9 or a 2.1mm.

I don't know if it can be done but over pressurize the system if you can to force a better atomization. To counteract it from drying to quickly use Reducer instead of thinner.

3/11/15       #7: Poor Atomization from HVLP turbine ...
Paul Snyder  Member


You should be getting great results by thinning the finish to 18 seconds in a Ford #4. I'd suspect the same thing as Pat, the air line that feeds pressure into the top of the cup is blocked somewhere.

There's a small air hose that goes from the gun body to the top of the fluid cup (see picture below). That hose supplies just enough air to the cup to keep the finish flowing freely when the trigger is pulled.

Test the air flow to make sure it's getting into the cup. The hose can get clogged inside the gun body if you tip the gun too far, inside the check valve in the middle of the hose, or inside the small air inlet in the cup lid. to test, attach the gun to the turbine and turn it on. Detach the hose from the top of the fluid cup lid and feel it to see if air is getting through the hose. If it is, check the air passage in the lid to make sure it's not blocked.

If you are getting a good air supply to the fluid cup, then the fluid passage inside the siphon tube or gun body may be blocked. Follow the gun stripping and cleaning directions to check.

Also, make sure the seal on the lid to the fluid cup is not leaking. It needs to be sealed well so the air supply to the cup will provide enough pressure to make the finish flow freely.

Another possible problem is the air hose from the turbine is crimped or too long.

When the gun is working properly, you should be able to spray any coating with excellent results as long as it's the correct viscosity. The 1.5 N/N is a good size to use when the viscosity is in the 18-20 second range using a Ford #4.

View higher quality, full size image (495 X 1024)

3/11/15       #8: Poor Atomization from HVLP turbine ...
Robert Member

Thanks for the responses everyone.

Paul, I'll check those things. I did have some finish sneak into my check valve at one point, and though I did my best to clear it completely maybe it just isn't performing perfectly. I ordered some replacement check valves and cup parts from homestead finishing today. Jeff told me he thinks the main problem was that I shouldn't have been using the mesh strainer at the fluid intake. I've never used a gun with a strainer before and was not aware that they shouldn't be used with pigmented finishes. Apparently the white particles aren't ground finely enough to make it through the mesh with ease. Hopefully that was my main problem.

Pat, how long do you think would be too long for the hose? I believe we're using a 25 ft. Which allows the turbine to be located just outside our booth.

3/11/15       #9: Poor Atomization from HVLP turbine ...

You should be able to spray the Resistant thinning it roughly 30%. Clawlock as the others said is heavy, so you may have to get closer to 40%. I did this for years before finally "splurging" for the AAA setup, (best move I ever made BTW). Unfortunately thinning this much also creates a ton of overspray, while putting less actual finish on the surface:(

I agree go through the gun and make sure there's no blockages. Those plastic pressure tubes, more specifically the little check valves in them, clog up very easily. I replaced them fairly often.

good luck,

3/13/15       #10: Poor Atomization from HVLP turbine ...
Sean Jackson Member

I shoot unthinned thick (CV) MDF primer all day long with a Fuji Q4 turbine with a 2.5m tip, it loves it. I cannot speak for 'clawlock' but the fuji is the best HVLP i've used to date.


3/13/15       #11: Poor Atomization from HVLP turbine ...

Have you also used a accuspray (3m) 10 gun? Or one of the newer applo guns? What is your opinion?

3/13/15       #12: Poor Atomization from HVLP turbine ...
Sean Jackson Member

Jim I've no experience of either, the apollo i used to have was low end.

3/14/15       #13: Poor Atomization from HVLP turbine ...
Denny J

I have the Accuspray model 10 GP gun that I run with the PPS system ans it sprays incredibly well. Most times superior to either of my AAA units but it doesn't have the volume they do.

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