We finish our table, desk, and cabinet tops with polyurethane varnish to build an impervious layer of protection.
Polyurethane varnish is superior to the lacquers and other materials commonly used for furniture finishes in these ways:
Because of the difficulties of application, varnish finishes are known for their thick and thin places, runs, laps, lines, and roughness from dust. We have learned to create a varnish finish without these defects with a surface that equals or rivals the best sprayed lacquer finish. "We have learned." Three words, many years. The breakthrough was the VOC scrubber we built to remove solvents from the air of the finishing rooms. This allows us to maintain temperature at 75 degrees and relative humidity at 45–50%. We filter and re-circulate our conditioned air.
The application of varnish is extremely sensitive to temperature and humidity. At the optimums we maintain, it dries quickly, but also flows out smooth. If varnish dries too quickly (higher temperature), laps and lines do not flow out. If it dries too slowly (lower temperature or higher humidity), it drips on the edges and captures dust. And if it dries too slowly, you must wait two days before sanding and recoating for it will "gum up" the sandpaper and cause other mayhem. A surprising additional benefit to the scrubber was its dust filtering efficiency. We have built a low tech clean room, scrubbed of vapors and dust.
Cleanliness is imperative. We vacuum. We blow the dust from clothes and tools before entering the room. All mixing and pouring of the material is meticulous to avoid contamination.