How to patch and sand timber before you stain it

January 22, 2025

Stain is unforgiving in a way paint is not. Paint sits on top and hides a multitude of sins, and stain soaks in, so every dent, every scratch and every bit of filler you did not quite get flush comes up darker or lighter than everything around it. The prep is the job. The staining is the easy bit at the end.

Patching the holes and cracks first

Nail holes, gouges and splits all need filling before you go near the sander, because sanding is what makes the filler flush.

Pick a filler you can stain over. This is the one that catches people. Plenty of fillers take stain differently to the timber around them and end up as a pale blob. Either get a stainable filler, or match the colour to the finished timber rather than to the raw timber.
Press it in properly. A putty knife, and press firmly so it fills the whole cavity rather than bridging the top of it. Leave it very slightly proud, because filler shrinks a little as it dries and you can always sand a high spot back.
Let it dry all the way. Sanding filler that is still soft in the middle drags it out of the hole and you start again.
Deep holes go in layers. Anything more than a few millimetres deep, do it in two or three goes with drying time between, or the outside skins over and the middle stays soft for days.

Sanding

Sanding does two jobs here. It levels the surface, and it opens the grain evenly so the stain goes in at the same rate everywhere. That second one is why you cannot skip straight to a fine grit.

Start around 120 grit to take out the rough and level the filler.
Finish at 240 or finer. Going too fine on softwood can actually close the grain and make the stain sit patchy, so 240 is usually the right place to stop for staining.
Always with the grain. Cross grain scratches are invisible on bare timber and glaringly obvious the moment stain goes on. This is the single most common reason a stain job looks wrong.
Do not lean on a power sander. Let the weight of the machine do it. Pressing digs swirl marks in that you then have to sand out by hand.
Edges and corners by hand. A block and a bit of paper. A machine will round an edge over before you notice.

Getting the dust off, which matters more than it sounds

Vacuum first, then wipe down with a barely damp cloth and let it dry. Dust left in the grain gets sealed under the stain as little dark flecks.

A damp wipe also raises the grain slightly. If you are after a really smooth finish, let it dry, knock it back very lightly with the fine paper, and then stain. That extra 10 minutes is the difference between good and very good.

Check it before you commit

Run your hand over the whole surface with your eyes shut, because you will feel a ridge you cannot see. Then look at it in raking light from the side rather than straight on, which shows up every scratch and dip.

Test the stain on an offcut or somewhere that will not show, and test it on a patched area, because that is where it will look different if it is going to.

Shop related products

V-Tech Wood Filler, Natural 50g. The one to reach for on timber you are staining rather than painting.
V-Tech Wood Filler, White 50g. For anything getting a painted finish instead.
Uni-pro Aluminium Oxide Sandpaper Roll, 80 Grit. For the heavy levelling before you step up through the grits.
Medium Sanding Block, 98 x 69 x 26mm. For the edges and corners a machine will ruin.
Diggers Timber Cleaner 1L. If you are working on something weathered rather than new.

Did you know we also carry a full abrasive range in store that is not all on the website, including Norton orbital sheets in 40, 80, 120, 180 and 240 grit, sanding belts, flexible discs and fine and medium abrasive blocks. Give us a ring on (08) 8536 4333 to check what is on the shelf.

What is online sits in hand tools and paint and accessories.

Picking the stain

We can talk you through which finish suits the timber and where it is going. Come in with the offcut if you have one, because it is much easier to answer looking at the actual timber than describing it over the phone.

More on timber

I have sanded across the grain on a tabletop and not noticed until the stain went on, and there is no fixing that except starting again.

Cheers,
Candeece

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Hardware

The everyday bits that hold a place together. Gate hooks and barrel bolts, pad bolts, door hinges, cup head bolts and nuts, and the odd thing you only need once every few years. Galvanised gear is what you want outside. Zinc plated is for indoor work and anywhere that stays dry.

If you are not sure which hinge or bolt suits your gate, bring the old one in to the Strathalbyn shop and we will match it at the counter.

Also worth a look: Fasteners and Fixings and Building Materials.