Short answer: Yes, on flat, solid wood surfaces you can usually sand varnish off without a stripper. Carvings, turnings, spindles and veneer are different. Sanding blurs detail on carved pieces, and it can sand straight through a thin veneer.
When sanding works well
Sanding is a good choice when:
- the surface is flat and solid wood
- the varnish is thin enough to cut through without a lot of effort
- you don’t mind losing some of the old patina
Sanding is slower and riskier when the finish is thick, the surface is detailed, or the piece is an antique. For antiques, read what not to do to antique furniture first. On those, a chemical stripper or a card scraper can be a better choice.
Grit sequence
Start coarse enough to cut through the varnish, then work finer in steps:
- 80 to 100 grit for thick or stubborn varnish. For thinner varnish, start at 120 or 150.
- 120, then 150 to remove the coarse scratches.
- 180, then 220 to prepare the wood for a new finish.
Don’t skip more than one grit. Starting too coarse is not a shortcut either, because deep scratches from coarse paper take much longer to remove.
Keep the paper from clogging
Varnish clogs ordinary sandpaper quickly. Use stearated, or no-load, paper, or an open-coat aluminum oxide. Change or clean the discs when they glaze over or start to heat up. Friction softens old finish and gums up the paper, which makes it cut less and burnish more.
A random-orbit sander suits flat surfaces. Finish by hand with the grain, because hand sanding removes the swirl marks that a random-orbit sander can leave. A card scraper removes varnish quickly on flat panels, with little clogging and little dust.
Veneer, edges and corners
Modern veneer is often about 0.6 mm (1/42 in) thick or less. Edges and corners sand through first, so keep the sander flat and go lightly. If you can see the core, or the grain pattern changes, stop. Is it better to sand or strip veneer? compares the two methods for veneered pieces. How to tell solid wood from veneer furniture explains how to check before you start.
Carvings, turnings and spindles
For carved or turned pieces, use a chemical stripper rather than sandpaper. Sanding softens crisp edges and fills in the detail you want to keep. How to strip varnish from wood furniture safely covers the stripper options and safety steps.
Sanding to recoat instead of removing the finish
If the old finish is sound and you only want a fresh coat, you don’t need to remove it. Clean the surface, then scuff-sand lightly with 220 to 320 grit to dull the sheen and give the new coat something to grip. Sand just enough to dull the surface, and don’t cut through to bare wood unless you intend to.
Compatibility matters. Oil-based polyurethane over old oil-based varnish is usually fine after cleaning and scuffing. Water-based finish over oil-based varnish needs more care. Let the old finish cure fully, scuff it, and test adhesion on a hidden spot first. Some manufacturers recommend a barrier coat of dewaxed shellac, so check the product label.
Dust and lead safety
Old finish dust can be irritating, and older paint layers can contain lead. Test for lead before sanding any painted piece made before 1978. Wear an N95 respirator or better and use dust extraction where you can. Keep the work area clean so dust doesn’t spread through the house.