Help with Finish Viscosity for Turbine Spraying

[Paul Canaris]

I have what I THINK IS A Ford #4 cup; water runs through it in 10 seconds. I am going to be applying General Finishes High Performance Polyurethane Water Based Top Coat. When I run it through my Ford#4 it takes around 70 to 80 seconds which seems way to thick to spray. Does 70 to 80 seconds even seem possible? Perhaps I did something wrong? Using a Apollo 1050VR with a 7500 gun to apply finish. Can this be thinned with water?

[John TenEyck]

I measure 65 - 70 seconds with a Ford #4 cup so your results are pretty similar. I thin it 10% with water to get it down to about 45 seconds so I can spray it through my 1.8 mm gravity feed HVLP conversion gun. The can says you can thin it up to 20% with water.

John

[Paul Canaris]

65 to 70 could have been what it actually was. I simply gave up looking after it hit 60 seconds. The booklet that came with the Apollo said 25 to 30 seconds for a Zahn #2 and I did not have a conversion chart. A Zahn must have a really big opening.

Good to hear you get good results.

Now I need to figure out what needle/nozzle combination to use. I was leaning towards a 1.5.

Thanks for the feedback, very helpful.

[John TenEyck]

A Zahn #2 reading of 26 seconds is 34 seconds through a Ford #4 cup, making it a pretty low viscosity finish. What orifice size is that recommendation for? You would have to think HP Poly a lot more than 10% to get it that low, and even though GF says you can add up to 20% water I would look to get a larger orifice/needle to avoid doing that.

John

[Jim Becker]

I agree with John...get the gun setup so it's right for your intended finish. Thinning a water borne finish is to be avoided if at all possible and no more than 10% if you have to. Why? Because despite the name on the container, "water" isn't the base/solvent for the finish. It's the carrier. When you add water, you're spreading out the actual finish molecules that are suspended in that carrier. Beyond a certain point (that proverbial 10%) you potentially start to have issues with the quality of the "finished finish", as it were... Once the water evaporates, the finish cures in the manner it's designed to do and if that finish is spread very thinly on the surface, it's just not going to look or feel right.

[Charles Neil]

Keep it simple, If it will go thru a medium mesh strainer about as fast as you can pour it in , your good to go.

I use GF High Performance all the time and an Apollo 1050VR. with a 1.5 needle/nozzle, I use it right out of the can..