Remodelaholic | Painting Wood Furniture: How to Permanently Cover Knots and Stain

Remodelaholic | Painting Wood Furniture: How to Permanently Cover Knots and Stain

Painting Wood Furniture: Preventing Tannin Bleed-Through

(How to Permanently Cover Knots and Old Stain)

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I love to build DIY furniture. Sometimes it’s new, raw wood and sometimes I’m covering up an old finish.

Either way, I’ve had painted wood furniture projects that looked great to begin with then, especially with white or light paints, the tannins started to bleed through. Frustrating!

So just what are tannins?

Tannins are naturally-occurring compounds found in wood and other plants, including those in coffee, tea and grapes/wine. They help prevent disease and regulate the plant’s growth.

Because of their chemical nature, the tannins seep to the surface, even after the wood is completely dried and carefully painted. The chemicals in wood stain do the same.

Stained wood, such as the mahogany finish on the wood pictured below, is the worst culprit. Knot holes are also repeat offenders!

More than once, I’ve gone through the recommended steps for painting wood furniture: sanding, applying primer, two coats of paint AND 2-3 coats of clear finish, just to see little pink spots coming to the surface.

It’s infuriating! Sometimes it’s even large, discolored blobs from knots in the wood.

I’ve tried just about every kind of primer you can buy, even “stain blocking” primers and the only product that has yet to fail me is my old standby shellac.

Painting Wood Furniture: Preventing Tannin Bleed-Through with Shellac

I first used shellac to get a smooth finish when painting MDF, but it also makes an amazing tannin-blocking primer as well. It comes in a brush-on formula or in an aerosol can.

Shellac can be covered in any kind of finish (oil-based paint, water-based paint, lacquer, etc.).

I have started applying a coat or two prior to painting every time I’m using a light color.

It dries very quickly so you can move on to painting without losing a ton of time. It’s worth the little bit of extra time, trust me!

Note: As always, follow the application instructions on the can carefully, following all guidelines.

How to Cover Knots When Painting Wood Furniture

Now what if you just have one or two problem spots, such as knot holes?

When I built my modern bachelor chests, I primed the raw wood with BIN stain blocking primer and thought I was good. Sadly, after a couple months, the knots started to show through!

My secret weapon? Clear nail polish! Clear Nail Polish Cover Knot Wood Tanin Stain WM 3000

Painting Wood Furniture: Preventing Tannin Bleed-Through with Clear Nail Polish

For a piece with just a few problem areas such as wood knots or spots that have been touched up with a stain pen or wood repair marker (which I’ve discovered is almost impossible to cover), the simple top coat you use for your manicure will do the trick!

Brush one or two coats of clear nail polish onto the areas, no need to cover the entire surface. Then fill in any gaps or indents (like around a wood knot) with wood filler.

In the sample board below, all the dark pigment is safely sealed beneath the nail polish and a first coat of paint. The indentation from the knot can now be easily smoothed over with wood filler.

Next time you pull out the white paint, remember to tackle the tannin bleed through first! A simple covering of shellac or a few spots of clear nail polish give you a simple prevention for bleed-through.

More woodwork and finishing tips and inspiration:

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This content was originally published here.