Oxford USL Spraying much better now - created 03-29-2009
Ryan, Michael - 03/29/2009.09:34:27
Never waste the challenge of a big mistake
Well, Long convoluted story.
I had not been achieving the finish I wanted with Oxford USL gloss on 2 OM guitars. Problems with sags, runs, bubbles. It is a fairly good finish but not great.
This is my 4th gun. I do like this gun but there was lots of sanding, rubbing down, buffing.
I currently need to reshoot part of the current guitar due to scratches (another story I wont bore you with) and had buffed thru. The finish after sanding out the scratches
My Spray gun is a Asturo HVLP eco/sx with 1.4 tip set. The gun is on a PC 4.5 hp electric oiless compressor. 25 of hose.
I spray at around 70 degrees this time of year.
I had never found water in my pressure tank and the drain is put in an untenable spot for me to reach and the compressor is in a weird hard to reach just right size spot. Well, I had not been draining it.
SO, Yesterday, I pulled out the compressor, drained it of a lot of rusty water - oops, put on a drain extension so I can reach it.
I also discovered I had my paper water throwaway filter on the wrong side of the regulator - another oops.
Now, I am getting 20-22 PSI at the gun trigger pressed - was only getting 15 before.
Once I got the amount of finish dialed in I am getting very even, very well atomized finish now. Hope that lasts. The finish goes on easily and does not sag nearly as much and I can get the perfectly homogeneous milky look I want regarding film thickness.
For anyone else with finishing problems, I feel stupid for so many errors in setup but watcha goin to do and I sympathize.
"Milky look" is, IMO too thick for USL, go a little bit lighter on each coat and it will lay down much better. It sounds like the fixes to your compressor helped a bunch, but spraying thick enough coats to see milkyness is asking for runs.
I should call it "slightly turbid" I have measured and the 2-3 mil thickness recommended has a slight homogeneous turbid or milkiness and it dries quickly and perfectly so far with my tuned up system.
If its working for you... do it your way, sorry for sounding like i know your setup better than you, spraying can be really frustrating, and im glad you have it sorted.
I am always open to input. I only have this going well for the moment. We will see if it stands the test of time and repeatability.
I also read on oxford's forum to have the slight turbidity indicating OK film thickness. I find if I don't spray wet enough I get a rough finish which seems to dry too quickly. I also spray my enduro wat-r-base to a wet look and slightly milky and it rarely sags. I kind of use for a rule of thumb that the finish dries within 10-15 minutes and can be sanded at 30-45 minutes as the right thickness also. Kind of reverse but does seem to work.
It seems that the difference between wet and saggy and just wet ain't much.