Sunday, May 19, 2013

PVA Resist Finish, or "Do You Think We Can Tell the Homeowner Batik Is Coming Back?"

I found this photo a few moments ago in a folder of files from the first digital camera I owned, about 12 years ago. I'm glad I found it, as it's an excellent illustration of something I tell my students all the time:

Don't remove excess glue with a wet rag! That's what the cabinetmaker did to this face frame.

The principle is simple: the water dilutes the glue and spreads it around, so you've just created an area of finish-resistant wood, which won't show until you apply finish. 

This was on a set of cabinets I finished for a cabinetmaker who wasn't willing to apply anything other than quick-dry poly. The homeowner wanted a stain somewhere between rosewood and cherry, and so I was called in to apply a water-based dye stain (a mixture of cherry, rosewood, and blue) under a clear coat of acrylic. The cabinets were soft maple, and looked great until I put the stain on. I took this picture as a way to help explain to the cabinetmaker why the job would take a week longer than he'd planned - - I had to sand everything he had built until the dye would take uniformly, which was a trial-and-error process. The finish-resistant area is invisible, though usually it's palpable, with the affected area feeling slightly slipperier than the bare wood. He must have used a sopping rag to wipe up his squeezeout, because the diluted glue had soaked deep into the wood.

I look back upon that extra week with those 30-plus cabinets and doors as one of my most miserable experiences in woodworking. 

The same principle is at play when you pretreat wood before staining it. Some use a thin coat of shellac for this, others buy various proprietary concoctions, but I have had great success with glue size. Mix 9 parts water to one part ordinary PVA glue (yellow or white wood glue), and wipe it on as the first coat of finish. Keep the whole surface saturated for a minute or so, then wipe it all dry. This tends to raise the grain a bit, so next scuff-sand with 220 grit, then apply your water-based stain. Add a coat of Zinsser's Seal Coat, then 2 coats of Ceramithane, and you have something to rival a cabinet factory finish, especially on figured maple:

Oh, and of course, as always, practice on scraps!

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