How to sand timber properly, grits, grain and technique

September 8, 2026

How to sand timber properly

Sanding is the least glamorous job in any timber project and it is the one that decides how the finished thing looks, because paint, stain and varnish all sit on top of whatever you leave underneath them. A dining table with years of wear in it, a chair somebody has loved to death, a set of doors that have gone dull. All of them come back with sanding, and none of them come back without it.

What sanding is actually doing

Two jobs at once. It takes the damage and the old finish off, and it gives the new finish something to hold onto. A stain going onto a surface that has not been sanded goes on patchy, because it soaks in unevenly, and paint over old gloss will lift the first time something knocks it.

Grits, and why there are so many of them

The number on the back of the paper is how coarse it is, and lower means rougher.

40 to 60 is coarse. This is for taking old finish off, levelling rough sawn timber, or shifting real damage. It leaves scratches, and that is fine, because the next grit removes them.
80 to 120 is the working range. Most of your time goes here, smoothing out what the coarse grit left behind.
180 to 240 is finishing. This is the pass that makes the difference you can feel with your hand rather than see with your eye.

Work up through them in order and do not skip more than one step, because a jump from 60 straight to 180 just polishes the coarse scratches rather than removing them, and you will see every one of them once the stain goes on.

By hand or by machine

For a small job, a sanding block and a sheet of paper is quicker than getting a machine out, and it gives you far more control on edges and mouldings. Wrap the paper around a block rather than using your fingers, because fingers make dips.

For anything with real area to it, a power sander earns its keep. The trick with a machine is to let it do the work. Pressing down does not sand faster, it just digs a hollow and burns the paper out.

Prep before you start

Wipe the surface down with a barely damp cloth so you are not grinding grit into the timber. Pull out any nails or staples, which is particularly worth doing on recycled timber, because a staple will tear a sheet of paper and will take a chunk out of a sander pad. If there is old paint or varnish on it, a scraper or a stripper first will save you a lot of abrasive.

The technique, which is mostly one rule

Sand along the grain, never across it. The grain is the direction the lines run, and scratches that follow it disappear into the timber while scratches across it stand out like a signature, especially under stain.

Keep the pressure even, keep moving, and check with your hand rather than your eye as you go, because your fingers will find a ridge your eyes will not.

For spindles, carvings and internal corners, fold the paper or use a sanding sponge, which will follow a curve in a way a block never will.

Finishing up

Get all the dust off before you put anything on it. A vacuum with a brush head, then a clean cloth. Dust left on the surface ends up suspended in your first coat and you will be sanding it again.

The safety bit, and it matters more than people think

Goggles and a mask, every time. Timber dust is not harmless and fine dust off a power sander hangs in the air for a long while. Old paint is the bigger worry, because anything from before the eighties may carry lead, and sanding that back releases it. If you are not sure what is on there, get it tested rather than guessing.

Sanding also makes a mess of a room, so if it is a decent sized job, set up in the shed or outside.

Shop related products

Supercraft Sanding Sheet Multi Tool 93mm, 12 pack. Assorted grits for a multi tool, which is the one that gets into corners.
Katana 18V Cordless Heat Gun. For lifting old paint off before you sand, which saves a lot of paper.
Uni-pro 25mm Utility Paint Brush. For the stain or varnish that goes on afterwards.
Supercraft 63mm Synthetic Paint Brush. Wider brush for flat surfaces once the sanding is done.
Uni-pro 5-in-1 Caulk Tool. Scraping and filling before the first pass with the coarse grit.

Did you know we keep the abrasives in store and they are not on the website. Sanding blocks in fine and medium, delta sheets in assorted grit, sanding belts in 40, 80 and 120 grit, Norton finishing sheets, and flexible abrasive discs from A36 through to A100. Give us a ring on (08) 8536 4333 to check what is on the shelf, or bring the job in and describe it and we will work out what you need. There is more in the hand tools range and the power tools range online.

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How to sand timber properly, grits, grain and technique