HVLP Still Learning

[Mike Goetzke]

I recently purchased a new Fuji Q4 Pro system. I posted a few questions before but now have had some time to play with it and have even more questions:

1) I was getting some air bubbling on red oak veneer ply with Target USL.

http://img.photobucket.com/albums/v212/mbg/My%20Tools/Fuji%20Q4%20Pro/IMG_2945.jpg
http://img.photobucket.com/albums/v212/mbg/My%20Tools/Fuji%20Q4%20Pro/IMG_2953.jpg


2) I soaped up my gun and found an air leak. Fuji CS has been great answering my questions. They said a small air leak at this joint is normal. After looking at the parts diagram I tend to think they are correct - there is no positive air seal between the fluid block and gun body.

http://img.photobucket.com/albums/v212/mbg/My%20Tools/Fuji%20Q4%20Pro/IMG_2929.jpg

3) Fuji sent me a new seal and suggested I use a sealer like de-waxed shellac. So I purchased some new Target EM6000 (formerly USL) and shellac. I had some scraps of extra ply so experimented by leaving some bare, stained some, shellacked some, & stained/shellacked some. I was disappointed when I was finding air bubbles again (most do smooth out). I wasn't about to give up so I dug up more samples and discovered if I increased the air or lowered the fluid level the bubbles were gone. Does this make sense?

The finish looks wet going on but guess I should get a gauge to see if the thickness is there.

I never had this problem with my older Titan 4-stage HVLP system but the Titan gun has the air control on the gun and it really didn't allow much variance - it was either on or off. So maybe since I had plenty of air with the Titan I didn't have the problem I'm experiencing with the Fuji.

Something else I learned from this experience - it is well worth it to apply a shellac seal coat first. It's unbelievable the difference between the grain detail, color, and depth on the samples I sprayed.

Mike

[Phil Phelps]

Mike, I really don't understand folks who get air bubbles in their clear coats. I don't think it matters if it's shellac, lacquer, or poly, you are either spraying with too much pressure and or, too thick material. Do you have an in line air regulator on your gun? It's hard to tell from the photos, but the middle pic of the oak apperars to be orange peel caused from too much pressure. You need to find the right mix of material and air pressure. I'd start with the proper reduction on your material. I'd choose thinner over thicker material anytime. Maybe a little teflon tape on the connection threads with stop those air leaks.

[Mike Goetzke]

Mike, I really don't understand folks who get air bubbles in their clear coats. :confused: I don't think it matters if it's shellac, lacquer, or poly, you are either spraying with too much pressure and or, too thick material. Do you have an in line air regulator on your gun? This is a turbine system. It has a ball valve at the gun inlet but no gauge. It's hard to tell from the photos, but the middle pic of the oak apperars to be orange peel caused from too much pressure. You need to find the right mix of material and air pressure. I'd start with the proper reduction on your material. My Fuji came with #3, #4, #5, & #6 air caps/tips/needles. I measured the viscosity (16 sec. in the Fuji cup) and tip #3 or #4 should work. I have tried both with similar results. I'd choose thinner over thicker material anytime. Maybe a little teflon tape on the connection threads with stop those air leaks. It's hard to explain but teflon tape will not seal the air leak. The fluid is sealed off well but this fluid block is surrounded by air and the air can escape where the block in fastened to the gun body.

Like I said above I lowered the fluid flow and the bubbles seemed to go away. I'm somewhat frustrated because I had a Titan 4- stage HVLP turbine system that worked fine. I'd set the fluid by eye and start spraying. I picked up the Fuji because I still got quite a bit of over-spray from the Titan and wanted a more efficient air cap design. Maybe it's user error, user inexperience, or a problem with the gun. I'm trying to make sure it's not an equipment problem. Might just be this system has a larger range of air pressure control that my old system didn't that takes a learning curve. On the positive side seems like I'm getting closer on how to tweak the guns settings.

Mike

[Caleb Larru]

I recently purchased a new Fuji Q4 Pro system. I posted a few questions before but now have had some time to play with it and have even more questions:

1) I was getting some air bubbling on red oak veneer ply with Target USL.

http://img.photobucket.com/albums/v212/mbg/My%20Tools/Fuji%20Q4%20Pro/IMG_2945.jpg
http://img.photobucket.com/albums/v212/mbg/My%20Tools/Fuji%20Q4%20Pro/IMG_2953.jpg


2) I soaped up my gun and found an air leak. Fuji CS has been great answering my questions. They said a small air leak at this joint is normal. After looking at the parts diagram I tend to think they are correct - there is no positive air seal between the fluid block and gun body.

http://img.photobucket.com/albums/v212/mbg/My%20Tools/Fuji%20Q4%20Pro/IMG_2929.jpg

3) Fuji sent me a new seal and suggested I use a sealer like de-waxed shellac. So I purchased some new Target EM6000 (formerly USL) and shellac. I had some scraps of extra ply so experimented by leaving some bare, stained some, shellacked some, & stained/shellacked some. I was disappointed when I was finding air bubbles again (most do smooth out). I wasn't about to give up so I dug up more samples and discovered if I increased the air or lowered the fluid level the bubbles were gone. Does this make sense?

The finish looks wet going on but guess I should get a gauge to see if the thickness is there.

I never had this problem with my older Titan 4-stage HVLP system but the Titan gun has the air control on the gun and it really didn't allow much variance - it was either on or off. So maybe since I had plenty of air with the Titan I didn't have the problem I'm experiencing with the Fuji.

Something else I learned from this experience - it is well worth it to apply a shellac seal coat first. It's unbelievable the difference between the grain detail, color, and depth on the samples I sprayed.

Mike

Mike, I have the same system and it took me a while to figure out how to apply with it without getting bubbles and that orange peel look.

My problem and from the looks yours also was that I was using enough pressure but not enough fluid. The size of the fan makes a huge difference also. Make sure you leave the air flow valve on your gun completely open. It also looks like you have your cap that controls your fan open too much. I leave mine screwed out at least 3 threads when doing large surfaces. It seems to help the bounce back.

When applying the spray I like to spray thick enough it looks like (for lack of a better term) a "pond" on top of the surface but not thick enough it runs. Holding the gun too far away will also give you the orange peel look. I try to keep my gun at least 6 inches and no more than 8 inches away. To be honest, the closer the better. When dry I have a very smooth finish very little between coats sanding or steel wool needed.

one more thing, my gun leaks air in the same spot. It doesn't seem to affect anything though.

[Mike Goetzke]

Just as an update. I think I have it figured out. I picked up a wet mil thickness gauge as suggested. Results showed I was indeed applying too much finish. It's recommended to apply a 2-4mil layer but I was getting almost 6. I was then careful noting the needle valve setting and air cap setting (used gold air cap and full air). I was then able to easily duplicate my results with a perfect finish. I think my paradigm was that this Fuji gun produces so much less over-spray than my old HVLP system. I now have a great finish and much less over-spray!

Thanks to all,

Mike