Painting Wood Furniture: How to Permanently Cover Knots and Stain


Painting wood furniture has its difficulties! Learn to permanently block tannin bleed-through from wood stains and knot holes with these two tried-and-tested options.

Also helpful: How to Choose the Best Paint for furniture  –  How to Refinish Wood Furniture (no sanding!)  –  Must Know Tips to Prep and Refinish Furniture

Red Brown Tannin Bleed Through White Paint Fix WM 3000

Painting Wood Furniture: Preventing Tannin Bleed-Through

(How to Permanently Cover Knots and Old Stain)

by Elisha of Pneumatic Addict

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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!

Dark Red Mahogany Wood Stain, prevent Tannin staining by Pneumatic addict on Remodelaholic

 

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.

Painting Wood Furniture, Prevening Tannin Bleed Through, Pneumatic Addict On Remodelaholic

 

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.

Brush Shellac Tannin Stain Primer for painting wood white from pneumatic addict on remodelaholic

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.

Zinsser Shellac Primer under White Paint prevents Bleed Through by pneumatic addict on Remodelaholic

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.

White Paint Shellac Primer Prevent Bleed Through WM

How to Cover Knots When Painting Wood Furniture

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

Knot Hole Tannin Bleed prevention for White Paint on wood by pneumatic addict on remodelaholic

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!

Knot Hole White Paint Tanin Stain Wood WM

 

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.

Cover Knot Hole Nail Polish Hack to prevent Bleed Through, pneumatic addict on remodelaholic

 

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.

Painting Light Paint Over Raw Wood, permanently hiding Knots in wood, pneumatic addict on Remodelaholic

 

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:

Please pin this for future reference!Painting Furniture, How To Permanently Cover Knots Holes, Stain, Red Wood By Pneumatic Addict On RemodelaholicOriginally published 04.11.2018 // Updated 04.16.2021

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About Elisha Albretsen