What Are The Pros and Cons of Shellac Wood Finish?

What Are The Pros and Cons of Shellac Wood Finish

Have you ever heard of a lac beetle?  Actually, that is something of a misnomer because it is not actually a beetle – it’s a scale insect.  It is found in the trees of India and Thailand and lives for only six months, eating, propagating, and secreting a resin known as lac.  The female lac beetle produces this resin and secretes it to form a protective shell for its larvae.

So what, you ask?  This is a woodworking site, not a site about insects.  And yet, these insects produce one of the earliest known wood finishes, a wood finish still used today.

What is Shellac?

Protective shell + lac = shellac

Someone figured out long ago, sometime around 1590 in India, that if this resin was good enough to protect the insect’s larvae, it would be good enough to protect wood.  Its uses expanded to include dyes, but primarily its use now is to convert it into shellac.  The resin is dried and processed into flakes that are then dissolved in alcohol to create liquid shellac.

Shellac is an excellent finish on furniture, but its use in today’s world does not end there.  It is possible you have it in your medicine cabinet.  Pharmaceutical companies use it to coat tablets, and cosmetic companies use it to manufacture hairspray.

If you buy a box of chocolate covered raisins at the movie theater, you’re ingesting the shellac used to coat them.  Nutritional supplements and coffee beans are also coated with shellac.  The dye made from lac also appears in many products, including chewing gum, frozen foods, wine, and jams.

If you’d like to learn a bit more about where lac comes from and how it is produced, we found a video that will walk you through this process.  It’s actually quite interesting and notes how it takes 300,000 insects to produce 1 kg of lac from which will come the shellac finished product.

The tree from which the lac is taken determines the color of the resulting shellac.  Shellac’s natural colors will range from a dark garnet (reddish, the birthstone of January) to dark brown, orange and yellow.  An amber or orange shellac adds richness to walnut and mahogany.

You can tint shellac with any color.  This comes in handy when you are trying to match an existing color or repair a piece of furniture.  All shellacs produce a glossy sheen.

But today, we want to talk about shellac in the woodworker’s shop as a finish for wood.

Is Shellac A Good Wood Finish?

As we mentioned earlier, some really smart people decided that if it was good enough to cover and protect an insect’s larvae, it would be good enough to protect wood from the elements (water and the sun’s UV rays).  He or she then learned it also made the wood look good.

Shellac enhances the natural grain of wood and is very versatile and easy to use.  It adds a smoothness to the surface of wood, acts as a sealer and moisture barrier, and does not create the “plastic” appearance of a polyurethane or lacquer

Shellac does not fade or yellow over time.  It is resistant to the sun’s UV rays, one of wood’s enemies, and so it maintains its integrity.

On Sale
Rust-Oleum Zinsser 304H 1-Quart Bulls Eye Clear Shellac
  • This product adds a great value
  • 1 quart
  • Seals, preserves wood, art, Statuary & metal
  • Traditional finish and sealer

It is very easy to apply and produces a fine and mellow finish to woods.  It is an excellent finish choice for walnut and mahogany woods.  Shellac also polishes well and is associated with traditional French polish finish on the finest furniture.

Shellac is reasonably durable and offers a high gloss finish.  We say shellac is reasonably durable because it is sensitive to heat – a hot mug of coffee or a hot pan can leave a white ring on a shellac finish.  If you are smart and careful and use a coaster or a trivet, this becomes a non-issue.

As for application, shellac can be brushed on, although serious cabinet and furniture makers prefer to rub it on with a cloth.  They also tend to be picky on the measure of cutting shellac – a little denatured alcohol is used for this purpose. 

Here’s a furniture maker demonstrating the application of shellac on a video we found for you.  He allows sufficient time for each of the 7 coats he applies, although shellac is quick-drying and uses 400 grit sandpaper and a soft steel wool treatment during the application process.

The first coat seals the wood; the second coat adheres to and bonds with the first, providing enough body for light sanding without disturbing the base coat.

Is Shellac Waterproof?

While shellac is not waterproof, it is highly water-resistant.  Its ability to withstand water for a few hours before being wiped dry makes it so.  Even if it leaves a white “shadow” or stain, the stain will fade as the surface dries completely.  Even if it doesn’t, a shellac finish is very easy to repair, much more so than lacquer.

Does Shellac Penetrate Wood?

This can be a little bit misleading when discussing wood finishes.  All wood finishes “penetrate” wood to an extent.  But shellac, just like lacquer, varnish, and water-based finishes, are “film-building” finishes.  The base coat will penetrate into the wood and lift the grain slightly.  Subsequent coats form a film on the surface of the wood.

Interestingly, some are used in combination with each other.  A shellac finish can, in turn, be finished with a coat or two of polyurethane.  Shellac, as we have noted, enhances the natural grain of woods, a feature you would want to preserve and protect. 

As an aside, we’ve written about polyurethane in earlier pieces, most recently here.

Polyurethane offers a clear, hard, and strong finish that will protect that feature.  However, the shellac coat applied last should be a dewaxed shellac, as the polyurethane will not adhere to waxed shellac.  If you watched the video we recommended earlier in this piece; you will hear the wax content of lac discussed.

Is Shellac Wood Finish Toxic?

If you’ve eaten chocolate-coated raisins or nuts, taken a medicine tablet, ground your own coffee beans, chewed gum, and are reading these words, you know the answer to this question.

Shellac comes from the lac, resin secreted by an insect.  It is 100% natural, although not vegan if that is important to you.  It is also 100% non-toxic and has FDA approval for use in coating foods, medicines, and cosmetics.  This makes it safe to use on children’s furniture, for instance.

It contains no volatile organic compounds (VOC), as distinguished from oil-based polyurethanes, although water-based polyurethane contains virtually no VOCs.  So no gasses or fumes are emitted from its use.

How Long Does Shellac Last On Wood?

Rust-Oleum Zinsser 304H 1-Quart Bulls Eye Clear Shellac

A base coat of shellac will seal cracks and crevices in the wood surface.  The second and subsequent coats of shellac will build upon the protection of the base coat and can be sanded lightly with high grit sandpaper to “shave” any raised grain in the wood.

A well-applied shellac finish will provide years of protection for the wood.  Repairs also become an easy process.  Applying denatured alcohol to a damaged area with a cloth will strip the shellac completely.  Then, apply a new coat of shellac to the stripped area with a fine brush for precision.

The alcohol will act as an “eraser” just like you were correcting a spelling error, and matching the color of the shellac with the existing color makes it new.  Scratches, stains from prolonged water exposure or heat, disappear, and the piece of furniture, the project you worked so hard on, is returned to its original finish.

Shellac vs Varnish

We now know shellac.  Varnish, on the other hand, differs from shellac in that it cures as it dries, resulting in a finish that is impervious to solvents.  It is harder and heavier than a shellac finish and requires fewer coats.  A shellac finish will generally be smoother than a varnish finish, as well. 

What Are The Disadvantages of Shellac As A Wood Finish?

If you’ve gotten the impression we like shellac as a wood finish choice, you are correct.  However, we’ve noted a couple of cons, and to be clear about them, they are:

  • Shellac is not as durable as other wood finishes and can be damaged. However, we’ve also discussed how easy it is to repair; shellac can be over-coated with a stronger finish.
  • Shellac is not heat-resistant. But, as long as you don’t put your hot coffee cup or a hot pan on the surface, it won’t matter.
  • Shellac is not water-resistant. Water stains will create a whitish, ghostish (if that’s a word) appearance.  But, again, it’s so easy to repair.

So, notwithstanding these disadvantages, shellac is still a wood finish option we like.  Don’t let these cons dissuade you from its use.

Making Your Own Shellac

De-Waxed Super Blonde Shellac Flakes 1 lb. (16 oz.)

Shellac flakes are available for purchase, and they come in dewaxed form as well as all-natural, usually at about a 3% ratio.  They also come in various colors, as we mentioned earlier, colors determined by the tree the lac came from.  You will find them for sale both online and at the usual DIY big stores.

Mix your own shellac in a “cut”:  the ratio of shellac flakes (measured by the pound) to alcohol (measured by the gallon).  One pound of flakes mixed with 1 gallon of alcohol will produce a 1-pound cut.  A 2-pound cut will give you a thicker shellac and a quicker build (coat upon coat).

But if you don’t need a gallon of shellac, though, go lower – 1 oz of flakes to 8 ounces of alcohol will produce a 1-pound cut, and 2 oz of flakes to 8 ounces of alcohol will give you a 2-pound cut.

Simply add the flakes to the alcohol in your chosen cut and color, and seal the container to allow the flakes to dissolve, about 24 hours.  Strain to remove any flakes that did not dissolve.

Making Your Own Shellac

By making your own shellac, you have the ability to produce your desired color and your desired amount.  This will make your furniture project truly yours, as well as make repairs very easy to match color-wise.

You can spray both your own mixed shellac and pre-mixed shellac on your furniture or cabinet project.  If you have an HVLP turbine system or an HVLP gun and compressor, this makes application easy.  You can even purchase pre-mixed shellac in spray cans (wax-free) for crevices you can’t reach with a brush or a cloth application.

As another aside, we have written about HVLP in a past piece which you will find here.

Easy to apply, easy to repair, showcasing your wood’s grain, drying to a glossy sheen, part of the traditional French finish, polishes beautifully, and you can make your own to color and thickness preferences in whatever volume you need.  Shellac has a lot going for it, to be sure.  Make it a part of your wood finish repertoire to give your furniture projects a touch of class.

Last update on 2022-09-25 / Affiliate links / Images from Amazon Product Advertising API