Spraying Black Stain: Special Techniques

Expanding my knowledge of how to spray different finishes through an HVLP system, I decided to spray black water-borne stain on a 90-gallon aquarium stand I'm making for a local aquarium store.  I decided to use black stain not just for giggles - I'm also experimenting with a number of different ways to achieve a nice black finish on cabinets.  I've tried a few already: oil-based black stain and varnish (troublesome), latex paint and polycrylic (sticky), and black-pigmented polycrylic over grey latex primer (the best so far).

My only problem with using black-pigmented polycrylic is that it masked the grain of the wood.  This isn't a bad thing per se, but I wanted to find another option that would allow the grain the show through, while still getting a jet-black color.

So I loaded half a can of black water-borne stain into my HVLP pot, and started up the turbine.  Of course, it took a little trial and error to dial in the proper air pressure, using a garden hose flow-control valve on the air hose.  Then I adjusted the pin travel on the gun, and the amount of air coming out of the air cap.  Eventually, I had good settings, and the spraying was going well, with minimum overspray and good coverage, with no splattering.


But then a problem cropped up: every once in a while, no stain would come out of the gun.  The air was still flowing, and the air pressure in the pot was still good, but for some reason, stain wasn't moving through the gun.  Could it be that the fast-drying stain was clotting in the gun somewhere?  or were clumps of pigment jamming the works somewhere inside the gun?

I stopped spraying and checked the gun - all clear.  Then I added a few tablespoons of water to the pot and mixed it well.  When I went back to spraying, I still had good coverage and color, but fewer "jams".  I think diluting the stain a bit helped.

As for the result: I am very happy.  The process turned my white birch case jet-black, but I could still see the grain underneath.  Now I just need to find a good water-borne clear coat that won't wash out the rich black color of the stain.  My plan?  I'm going to color some polycrylic again.  But THIS time, I'm going to use dye, rather than pigment, to give the poly its black color.  I hope this lets the grain show through, without imparting a wan, washed-out look to the piece.