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designing and building with wood channels my creativity and challenges my mind.
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Friday, March 11, 2011

New Discoveries in Blackness

I have been searching for the "perfect" solution to putting a jet-black, satin finish on the aquarium stands I have been building for custom clients and Skipton Unique Aquaria and Reptiles, in Boston, MA. 

I have tried many different finishes and sequences over the past months, but now I have made a major breakthrough that should be helpful to anybody who wants an easy, satin black finish.

My first attempt, several months ago, began with a coat of shellac sanding sealer, then water-borne black stain, followed by a coat of high-end polycrylic.  I was dogged by bruch marks and the constant desire to touch up my work, which inevitably led to another coat of finish, just to make things "right".   The end result was alternating coats of stain and clear coat, and I was exhausted.

After I purchased a used HVLP system (3M Accuspray), I was able to spray on my finishes, which helped a lot.  My first attempt with the sprayers consisted of grey gripper primer, followed by latex interior black paint, followed by polycrylic clear coat.  The paint stayed soft for a long time, and picked up smudges easily.  Not good for salt water tank stands!

When I went to spray on the poly, I found that I got a huge amount of overspray.  If I adjusted the needle travel and fan pattern down to minimum, I got dribbles of finish and runny coats of poly.  After a call to Duane at 3M (in tech support - he is incredible), I tried a suggestion: putting a garden hose ball valve into my air line, so I could adjust the PSI at the gun.   This worked great for controlling the spray, but the clear coat was still going on unevenly - shiny in some places where the coverage was thick (almost runny), and matte in places where it had gone on in tiny droplets.

I wanted to avoid having to rub out this finish, which would have given it an even gloss.  But rubbing out isn't an option for these base-model stands.

Finally, i hit upon my current solution: clear polycrylic, dyed with black UTC (universal tinting color).  Genius!  The black poly (and it was BLACK), went on evenly, and imparted a powder-coated look to the stand.  It was as fast-drying as un-dyed polycrylic, and there was no need to re-coat.

I am very pleased.  My next test: try the dyed poly without any paint underneath.  Perhaps just primer, or perhaps just a coat of shellac.  This is less expensive than using water-borne black stain (which works very well but is too expensive), but I'm hopeful about getting a nice deep satin black.

here are pics:

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