I've been having some trouble spaying shellac. When it gets humid, I get water damage in the shellac finish. I have a filter on my air compressor, but sometimes water gets through it. I have a belt drive 5.5hp two-stage compressor.
What is the best way to remove the water from my air compressor output?
The moisture extractor should be at least 25' away from the compressor. You need some distance in order to allow the moisture in the air to condense. After the extractor, you connect the hose to your spray equipment. I don't think an extractor does very much good located on or close to the compressor.
Also, it helps to incorporate a simple drop leg of pipe with a drain valve to collect moisture in your air line before it goes through your extractor. This way your extractor won't have to work as hard. Again, put this downline at least 25' from the compressor.
If you still have a little moisture getting through your extractor, you can get a disposable in-line air filter. This is a small filter that installs at the end of your hose that connects to the gun. Ones I use are little blue plastic-cased things made by Sharpe. They come 2 to a package.
I'm also told if you use a better grade of alcohol when you mix shellac, it sprays better and helps prevent the blushing.
A lacquer retarder added to your shellac solution will help, as will using a slower evaporating alcohol like isopropanol, which can be added to your existing finish. Also, spray lighter coats.
Comment from contributor J:
A way to avoid blushing in bleached shellac ethanol solutions is to add them ammonia in order to decrease surface tension on the film. Solutions must be diluted to 10% of solids or less to avoid "orange skin" microgelation trouble. Decolorized shellac solutions can be treated with ammonia regardless of concentration probably because natural polymer is less acid (pH at 10%w/w 4.77).