Can a 3 stage turbine with the Appollo 7500C spray gun spray HD Polyurethane

[Bill A]

I have an Advance Machinery 300S, 3 stage turbine (these are the folks who make the Apollo systems- they made this unit about 5 years ago under the company name). I'm using a 5010 spray gun and trying to spray General Finishes High Performance water based Polyurethane.  I've tried to thin the poly by 10%, but the atomization still didn't look right (it didn't flatten right). Apollo says the tip size I'm using is OK.  I'm not happy with the results, even though all parts of the system seem to be working. I'm finishing furniture.

I wonder if I change spray guns to the 7500, if I will get good results.

I would like to avoid buying another turbine if I can solve the problem with a new gun ($300 vs $1200-$1500)
Any one have any thoughts or experience in this area?

 

[tiralie]

Bill:
Welcome to FOG.
I don't use General Finishes, but I spray Target Polyurethane which is close.

I've tried to thin the poly by 10%, but the atomization still didn't look right (it didn't flatten right).

You shouldn't have to thin to spray polyurethane with a 3 stage machine.

What did you thin with? The recommended thinner is EF extender.
What do you mean "it didn't flatten right"? Is it rough to the touch but even? A picture would help.
What was the temperature when you sprayed? If it's too cold it will increase the viscosity and make it difficult to spray.
Is this the first coat of the polyurethane you have sprayed on this furniture or one of several? If not the first, how long did you wait between coats?
What is the base coat?

I wonder if I change spray guns to the 7500, if I will get good results.

If previously you got the results you wanted with your 5010, I wouldn't change the gun.

Tim

 

[Bill A]

This was the first coat and it was on bare wood that had been finished up to 220 grit. I thinned the water based poly with tap water , per general finishes recommendation. The droplet size was really large which made the finish look bumpy instead of flat. I was spraying in the summer, so the shop would have been 80+ degrees.

Do you spray with a turbine based help system?

 

[tiralie]

Do you spray with a turbine based help system?

Yes. I have a Fuji Q4. I have to turn the air down to spray polyurethane.

Bill:
Sounds like you are not getting enough atomization.
Check the air cap on your gun. If you hold it up to the light you should see light through the tiny holes surrounding the main (needle) hole.
If these are plugged soak your air cap in a water bourne line cleaner or solvent that will dissolve the dried coatings in the holes. I have found that brushing with an old toothbrush usually dislodges the crap but it takes a couple soakings and brushing.
Tim