The trick to clear-coating a project quickly, says finishing expert Bob Flexner, is in the second coat. The first application of any finish acts as a sealer, filling pores and locking any errant wood fibers in place. But the second coat begins to add visual depth and protection. In a time crunch, you need a finish that cures to a sandable hardness fast enough for you to apply that critical second coat.
A few caveats, though: Film-forming finishes start their journey to film-dom when solvents or thinners begin to evaporate, a process that happens best in warmer temperatures. In cooler-than-ideal conditions, accelerate the drying speed by circulating the air around -- not on -- your project using small fans. This keeps air flowing without blowing dust directly into the drying finish.
You could run into the opposite problem in a warm shop: Dry winter weather causes some finishes to dry too quickly, broadcasting brush strokes and locking drips in place. Where necessary, thin finishes for easier application.
And crack a window or door to keep a fresh air exchange even if it means cranking up the heat for a time. Then check the calendar and choose one of the following fast-drying finishes.
Three days before Christmas: Aerosol Lacquer
Because it cures by evaporation, lacquer dries extremely fast, but the high solvent content means continued off-gassing of noxious fumes that could knock Santa on his bowl-full-of-jelly backside. So wrap up a lacquer finish with a couple days to spare.
Spray the first coat starting with the nooks and crannies, moving to edge and end grain, and finishing with wide flat surfaces. Begin each sweep off the wood, moving across the project, and then off the other side, overlapping the spray pattern as you progress.
After the first coat dries (30-45 minutes in a warm, dry shop, 60-90 in a cold or humid shop), sand with 320-grit sandpaper, remove the dust, and apply a second coat. No more sanding after that first coat, and you can recoat as quickly as the previous one dries. Let the project sit in a well-ventilated area on the 23rd and 24th before dropping it under the tree.
The downsides: Aerosol lacquer works great for small giftables but becomes pricey for large projects. And lacquer's fumes necessitate both ventilation and a respirator when spraying.
Two days and counting: Shellac
Another evaporative finish, shellac dries nearly as quickly as lacquer. But the fumes from Shellac's solvent -- usually denatured alcohol -- aren't nearly as potent, allowing you to push your deadline a bit.
Pre-mixed shellac found on home-center shelves usually comes in a 3-pound cut (three pounds of shellac flakes for each gallon of alcohol). To speed drying and improve brushability, thin this to a 1 1/2-pound cut, mixing equal parts finish and denatured alcohol.
Then use a natural-bristle brush and spread the shellac quickly to avoid noticeable brush strokes. If you leave gaps of unfinished wood in your stroke pattern, don't try to rebrush them; catch them on the next coat.
Allow the first coat to dry for 90 minutes in a warm and dry shop (two hours in a cold or damp shop). Then sand lightly with 320-grit sandpaper, cleaning or switching the paper if it starts to gum up. Remove the dust and repeat for the remainder of the day -- coat, dry, sand -- until you are satisfied with the buildup. Give your project a rest on Christmas Eve and give it away on Christmas.
The downside: Shellac has a limited shelf life (around three years). So, if you can't find a manufacturer's date on the can, ask the retailer about the freshness of their stock on hand.
'Twas the night before: Water-based Poly
Water-based polyurethane has many advantages: It dries fast, builds fast, and puts off only minor fumes, so you can finish indoors.
For best results, stir the can well, and apply with a synthetic or foam brush. Use a brushing technique similar to that for shellac: Work fast, apply a thin coat, and avoid overworking the finish.
Allow two hours for the first coat to dry. If the grain raises noticeably, don't sweat it. Sand it smooth again with 220-grit sandpaper, remove the dust, and apply the next coat. Water-based poly builds fast, so two or three coats usually suffice.
The downside: Because it dries so quickly, water-based polyurethane can be finicky to brush. It is temperature-sensitive. And it raises the grain. But follow the steps above, and when the last coat dries, the minimal fumes mean you don't have to wait. Drop the gift under the tree, nestle yourself snug in your bed, and watch visions of sugar-plums dance in your head.
Bob Flexner's book Wood Finishing 101 offers a step-by-step look into a variety of finishes. Buy it here:
Tip of the Day
You've glued some solid-wood edging on a set of plywood panels and now it's time to trim the edging... read more