Staining and Varnishing Wood Floors

Intro

Finishing a wood floor requires a number of preparation steps, but the result is a wood floor with all its warmth and richness.

If you're planning to refinish an existing floor, pull up a floor register to make sure you have enough wood for another sanding. Standard hardwood strip flooring can be sanded several times, but if your floor is only slightly more than 1/2 inch thick, consult a professional. The same goes for engineered flooring. It can be refinished, but its top layer is quite thin.

Take inventory of the existing floor and mark and repair popped nails and damaged areas. Because depressions in an old floor are inevitable, they'll show up as you're sanding them. Mark them so you can resand them if necessary.

Even if your floor is brand new and unfinished, it will require sanding and preparation. In almost all cases it's easier to use a pad sander rather than a drum sander.

Prestart Checklist

Time
2 to 4 days, depending on conditions and size of the floor and your skills and experience

Tools
Pry bar, putty knife, hammer, pad sander, random orbit sander, vacuum, finish applicator, paintbrush

Skills
Preparing, sanding, and finishing wood

Materials
Finishing nails, wood putty, stain, sandpaper, varnish

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Step 1

Remove shoe molding and baseboard (if desired). Rough-sand the floor with a heavy-grit paper, keeping the sander moving and working with the grain. Change sandpaper often to keep the cutting surface fresh. A sander equipped with a dust-removal system will speed the work.

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Step 2

When the floor is sanded to a rough-cut smoothness, fill the entire surface with a wood filler as recommended by your floor products retailer. Let the filler dry.

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Step 3

Rough-cutting the floor will leave the edges slightly higher than the main body of the floor. To even out this difference in floor levels, scrape down the edges so they're level with the sanded surface. Change blades often and pull the scraper toward you with firm pressure on the wood.

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Step 4

Buff the floor with a 100-grit screen to remove any remaining imperfections and to bring the floor to a consistent level from edges to center, leaving the surface at its finished smoothness. Vacuum thoroughly and remove dust with a tack cloth.

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Using a Drum Sander

Drum sanders require a specific technique to produce a smooth surface. Start about two-thirds of the way along the length of one wall and sand with the grain, pulling the sander towards you. Then, push the sander forward and overlap its next path slightly. After sanding the section turn the sander around and repeat the process.

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Step 5

Stain the floor (optional) with a rag or the applicator recommended, removing the excess if required. Let the stain dry. Using a lamb's wool or other suitable applicator, apply the finish coats, letting each coat dry. Scuff-sand and vacuum each dry coat before applying the next one.

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Choosing the right finish

Interior stains are generally wiping stains applied to bare wood with a protective clear coat.

Wiping stains:
-- Apply to bare wood with a rag or brush in maximum 2-foot sections. Let stand 5 minutes; wipe excess with rags; allow to dry overnight.
-- Darkness will depend on stain, color, porosity of wood, time left on before wiping, how hard it is wiped, and number of coats.

Oil finishes are based on drying oils such as tung or linseed oil.
-- Apply to bare wood, often over wiping stain, with brush or rag. Let stand for 5 minutes; wipe excess with rag; dry overnight.
-- Provide a rich satin finish and moderate water resistance.

Varnishes -- solvent base
-- Applied to bare or stained wood with natural bristle, nylon, or polyester brush.
-- Stir matte finishes without making foam; do not shake.
-- Let first coat dry 24 hours. Sand first coat to ensure adhesion.

Varnishes -- water base
-- May be milky white in the container but dry clear. May appear more like plastic than solvent-base varnish.
-- To remove whiskers that come up when applying the coating, predampen bare wood.