Shellac - What, When, and Why?

Jimsky

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Before the advent of modern spray-on one-coat varnish, hand-padded shellac-based finishes were used to create a flawless, aqueous gloss. As you can guess, today's discussion about wood finishes is designated to Shellac, which is the most underrated of all finishes.

Shellac (/ʃəˈlæk/) is a resin secreted by the female lac bug on trees in the forests of India and Thailand. (The word lac means "one hundred thousand," referring to the number of insects found on a single branch. Approximately 1.5 million bugs must be harvested to make 1 pound of shellac.) The resin is scraped from the twigs and branches of the trees. It's then melted, strained to remove bug parts and other foreign matter, and formed into large thin sheets that are broken up into flakes sheets. Those sheets are processed and sold as dry flakes and dissolved in alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze, and wood finish. Shellac functions as a tough natural primer, sanding sealant, tannin-blocker, odor-blocker, stain, and high-gloss varnish. Shellac was once used in electrical applications as it possesses good insulation qualities and it seals out moisture. Phonograph and 78 rpm gramophone records were made of it until they were replaced by vinyl long-playing records from the 1950s onwards.

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It is well known for its weaknesses-short shelf life and poor resistance to water, alcohol, heat, and alkalis. It is seldom mentioned for its strengths, which include some attractive characteristics:
  • Shellac is the only finish with a proven track record for longevity. It was the favored finish for quality furniture throughout the nineteenth and early part of the twentieth century. Much of this furniture has survived with its original shellac finish in very good shape.
  • Shellac forms an excellent barrier against water vapor (humidity) exchange, silicone contamination, and existing stains caused by water, grease, crayons, or natural wood resins. Many professional refinishers use shellac regularly for their first "sealer" coat because of this quality.
  • Shellac is unsurpassed as a touch-up material for repairing rubs, scratches, and gouges in other finishes. It bonds well to almost all finishes without damaging them, and it dries quickly.
  • Shellac resin is so safe it is approved by the Food and Drug Administration (FDA) for use as a coating on candy and pills.
  • Shellac's solvent, denatured alcohol, is not as polluting to the atmosphere as mineral spirits or lacquer thinner, and it is not harmful to you unless you drink it or breathe excessive amounts of it. (As with most liquids in the shop, you should also protect your eyes.)
THE LOOK: Shellac is more of a process than a look in itself.
SEEN ON: A wide range of 18th- and 19th-century antiques, especially French polish and European pieces.
HISTORY: Shellac was first used in ancient China for varied applications, including as a base for lacquer, as a glue, to pigment cosmetics, and to preserve food. Europeans discovered it when trade routes opened up during Marco Polo’s time. It’s since been used as a base for finishes and varnishes—and to re-create the look of Chinese lacquer.
GOOD FOR: A sealing coat before other finishes (for instance, a coat of shellac serves as a great buffer between an oil stain and an oil finish). It’s also used as the base of many wax or oil finishes and is the main ingredient of French polish.
PROS: Protean product with myriad applications that’s nontoxic and dries quickly, yet is quite forgiving to use. Mixed with color, it provides an easy way to repair and upgrade almost any piece or to execute spot touch-ups.
CONS: Does not provide total protection against water, alcohol, or heat.

Categories of Shellac

Natural shellac resin is orange in color and contains about 5 percent wax. You can buy shellac with its color intact or bleached out, with its wax included or removed, and in liquid or solid-flake form.

Coloring​

Shellac is either orange (also called amber, garnet, or button) or bleached (called clear or white). You can use orange shellac to advantage on dark woods to add warmth. Clear shellac is better for light, or bleached, woods when you don't want the finish to add color. See the image of Shellac flakes color below.

1280px-Shellac_varities.png


The orange color is the remainder of a red dye which gave shellac its original value. The dye was separated from the resin and used to color cloth. Orange shellac is a natural toner. It will darken the color of the wood without obscuring it. You can also add your own alcohol-soluble dye to make shellac any color you want. As long as you keep the color weak, you can usually brush the toner on without causing streaks. Otherwise, it's better to spray it on.

Wax in Shellac​

Most shellac still contains its natural wax. This wax settles to the bottom of the container. When you stir a can of shellac, you often see the lighter-colored wax rise to the top and become mixed in with the finish. (The wax makes clear shellac appears white, which accounts for the name "white” shellac.)
The wax reduces the transparency of the shellac on the wood. It also makes the shellac even less water-resistant, and it prevents good bonding when non evaporative finishes (varnish, water-base, and conversion) are applied over shellac. You can buy dewaxed clear shellac (often sold as "blond” shellac), but dewaxed orange shellac is difficult to find in small quantities. You can dewax your own shellac by letting the wax settle, and then pouring or siphoning off the clear part (straining is less effective). If you pour the dewaxed shellac off, do so very gently. The wax is easily stirred up. You can see what you're doing better if you work from a glass jar.

Liquid and Flake Shellac​

You can buy shellac as a liquid or as solid flakes that you make into a liquid yourself. Liquid shellac is sold in 3, 4, and 5-pound "cuts." The cut is a measuring term used universally to indicate how many pounds of shellac flakes are dissolved in 1 gallon of alcohol. The higher the cut number, the more concentrated the shellac and the thicker the solution. For example, you are getting twice as much shellac in a quart of 4-pound-cut solution as you are in a quart of 2-pound cut solution. Most of the shellac sold in paint stores is 3-pound cut: 3 pounds of shellac to every gallon of alcohol. You can use the shellac right out of the can, or you can thin it to whatever degree you want. You should use denatured alcohol, sometimes sold as shellac thinner, for thinning.
The problem with buying shellac in liquid form is that it is seldom very fresh. Shellac is like milk: It has a shelf life. From the moment the shellac flakes are combined with alcohol, the resin begins losing some of its water resistance and its ability to cure hard. For some time the curing is just slowed. Eventually, the shellac refuses to cure at all. It remains gummy on the wood.
The process is very slow, you couldn't measure it day-to-day, and there's no clear point at which the shellac should no longer be used. Just as with milk, the deterioration is accelerated by higher temperatures. If shellac is kept cool, it may cure hard for a couple of years. (Some manufacturers claim up to three years.) But the curing will definitely take much longer. It's a common rule among finishers never to use shellac that is more than six months old without checking it first.
To check shellac for freshness, put a drop of 2- or 3-pound-cut shellac on the top of the shellac can or another non-porous surface such as glass, and let it cure overnight. If you can push your fingernail into any part of the drop the next day, the shellac is questionable. Wait several more days to make sure the shellac will still cure hard before you use it.
Clear (bleached) shellac has a shorter shelf life than orange shellac. The bleaching that's done to take the color out of the shellac causes it to deteriorate faster. You should be more diligent in checking clear shellac for its ability to cure hard. Unlike orange shellac, bleached shellac deteriorates in flake form as well as in liquid form. You will have difficulty dissolving old bleached shellac flakes, and the solution may not cure hard.
If you find out after you've applied the shellac that it doesn't cure hard, you'll have to remove it with alcohol or paint-and-varnish remover and begin all over again with fresh shellac. You cannot fix a gummy shellac finish by applying a new coat of fresh shellac on top. Though this may give the appearance of correcting the problem, it will lead to greater problems later. The fresh coat will begin cracking much sooner because of the soft coat underneath. One of the oldest painter's rules is, "Never apply a hard finish over a soft one."

One way, and probably the best (IMHO) to ensure maximum freshness, is to dissolve your own shellac from solid shellac flakes. Here's how to do it:
  1. Using a non-metal container, combine the correct proportions of shellac flakes and alcohol for the pound cut you want. Suggest you begin by making a 2-pound cut, adding I pint of denatured alcohol to a quart jar containing 1/4 pound of shellac flakes. This will give you the feel of how to do it. You can then try thicker solutions.
  2. Stir the mixture several times during the next couple of hours to keep the flakes from solidifying into a lump at the bottom of the jar.
  3. Keep the jar covered when you're not stirring the shellac so moisture from the air isn't absorbed by the alcohol.
  4. When the flakes are totally in solution, strain the shellac through a paint strainer or loose-weave cheesecloth into another quart jar. This will remove impurities.
  5. Write the current date on the jar so that later you will know when you mixed the shellac.
  6. If you want to dewax the shellac, let the wax settle (this could take weeks). Then pour or siphon off the dewaxed layer into another jar. If you're in a hurry, you can try straining the shellac several times through tightly woven cloth until the solution is clear.
Applying Shellac

Shellac is very user-friendly. You can brush or spray shellac easily as long as the shellac is not too thick. By adding a drop or two of oil to a rubbing pad, you can apply the shellac to wood by a method called French polishing. French polishing is time-consuming, but it produces excellent results, and it is fun to do. In addition, the common thinner for shellac, denatured alcohol, doesn't smell bad and is not harmful to breathe in moderate amounts.

I hope this was informative for you, to expand your knowledge in wood finishes. Should we continue our discussion covering another finish - Lacquer?

*** All credits to C. Pourny and B. Flexner for knowledge sharing in their wonderful books.
 
Basics course, always good. I think french polishing is ball matting, in Germen "Ballen Mattierung", whereby a hand-sized bundle of cotton fabric is formed and soaked. The wood is processed with this bundle. A very accurate possibility. This has been done in Germany for generations, and not just with shellac. I use this method too, not just on ships. Thank you for your contribution, very useful!
 
Basics course, always good. I think french polishing is ball matting, in Germen "Ballen Mattierung", whereby a hand-sized bundle of cotton fabric is formed and soaked. The wood is processed with this bundle. A very accurate possibility. This has been done in Germany for generations, and not just with shellac. I use this method too, not just on ships. Thank you for your contribution, very useful!
Thanks, Mash. Since you bring up the 'French Polish' I'd like to describe this method of finishing so our members are aware of it.

French polish is a classic historical finish for fine antiques. In terms of beauty, it is without peers. The resulting surface is so pure it seems as though you could reach right inside the grain. The basis of the technique involves shellac, alcohol, pumice, and a few drops of oil, but all refinishers have their own French polish recipe and are emphatic that their way is the right way. You can simply ruined numerous furnishings trying to apply this deceptively simple method, but if you’re
less pigheaded, you can stop at any step in the process and finish the piece with wax.

THE LOOK: A deep, transparent, mirror-like shine. Variations of the technique involve mixing pigments with the shellac or working with a colored background to
create intoxicatingly deep hues.
SEEN ON: 18th- and 19th-century European pieces, mahogany furniture from the 19th century, and überglossy Art Deco pieces.HISTORY: Cabinetmakers have always sought the purest finish to enhance their creativity. Efforts to copy the high shine of Asian lacquer techniques achieved the greatest level of refinement in France with this particular process and combination of ingredients.
GOOD FOR: Enhancing the clarity, tone, grain, and patterns of the most refined antiques, pieces with beautifully figured wood or elaborate marquetry. Equally
transformed by French polish: Victorian furnishings, which can be found cheaply in antique stores and flea markets, not to mention vintage pieces with bad finishes.
PROS: Offers unparalleled clarity and beauty: Think water on bare wood. Although technically not the most resistant finish, it doesn’t require maintenance. French
polish can be repaired, patched up, upgraded, and enhanced without prior stripping or cleaning. Can be used as the base for other finishes.
CONS: Technique needs experience and practice and can be tedious. Offers low resistance to abrasion and liquids as well as heat damage.

 
Thanks, Mash. Since you bring up the 'French Polish' I'd like to describe this method of finishing so our members are aware of it.

French polish is a classic historical finish for fine antiques. In terms of beauty, it is without peers. The resulting surface is so pure it seems as though you could reach right inside the grain. The basis of the technique involves shellac, alcohol, pumice, and a few drops of oil, but all refinishers have their own French polish recipe and are emphatic that their way is the right way. You can simply ruined numerous furnishings trying to apply this deceptively simple method, but if you’re
less pigheaded, you can stop at any step in the process and finish the piece with wax.

THE LOOK: A deep, transparent, mirror-like shine. Variations of the technique involve mixing pigments with the shellac or working with a colored background to
create intoxicatingly deep hues.
SEEN ON: 18th- and 19th-century European pieces, mahogany furniture from the 19th century, and überglossy Art Deco pieces.HISTORY: Cabinetmakers have always sought the purest finish to enhance their creativity. Efforts to copy the high shine of Asian lacquer techniques achieved the greatest level of refinement in France with this particular process and combination of ingredients.
GOOD FOR: Enhancing the clarity, tone, grain, and patterns of the most refined antiques, pieces with beautifully figured wood or elaborate marquetry. Equally
transformed by French polish: Victorian furnishings, which can be found cheaply in antique stores and flea markets, not to mention vintage pieces with bad finishes.
PROS: Offers unparalleled clarity and beauty: Think water on bare wood. Although technically not the most resistant finish, it doesn’t require maintenance. French
polish can be repaired, patched up, upgraded, and enhanced without prior stripping or cleaning. Can be used as the base for other finishes.
CONS: Technique needs experience and practice and can be tedious. Offers low resistance to abrasion and liquids as well as heat damage.

I wonder how stable it would be in high humidity and high temperature locations. As noted water may present problems and particularly with annual repeated cycles. ????? Some parts of China would possibly have those present. Rich (PT-2)
 
I wonder how stable it would be in high humidity and high temperature locations. As noted water may present problems and particularly with annual repeated cycles. ????? Some parts of China would possibly have those present. Rich (PT-2)
Hello Rich, I think by applying shellac you can protect the wood piece from high humidity. However, it will not protect from water and high heat.
 
Basics course, always good. I think french polishing is ball matting, in Germen "Ballen Mattierung", whereby a hand-sized bundle of cotton fabric is formed and soaked. The wood is processed with this bundle. A very accurate possibility. This has been done in Germany for generations, and not just with shellac. I use this method too, not just on ships. Thank you for your contribution, very useful!
French polishing using the "Ballenamattierung" method is good for flat surfaces, e.g. concert piano, and less for curved surfaces. French polishing is an art and requires a lot of experience to achieve a high-gloss finish without streaks and white spots.

I used shellack on my Endeavour and will continue to use it on my future models.
 
Der Jim
This article is just comprehensive and thorough, which will no doubt help us along the way. thanks :)
 
French polishing using the "Ballenamattierung" method is good for flat surfaces, e.g. concert piano, and less for curved surfaces. French polishing is an art and requires a lot of experience to achieve a high-gloss finish without streaks and white spots.

I used shellack on my Endeavour and will continue to use it on my future models.
Not just for straight things. I also use it on curved furniture parts or entire cabinets with carvings. It is true that it takes a lot of experience and patience. The bale must also have the right composition. Today one no longer has to resort to "mysterious" tinctures. The ready mixes give the same result, optically and for a medium-term period.
 
Awesome discussion! I learned a lot! Thanks. I am still partial to my water based satin or matte sheen polyurethane…I am a neanderthal when it comes to finishes on my models…sigh! :)

If poly works for you and you're happy with the results, then that's the best method.

It's always nice to play around and experiment with other techniques, but when it really matters, stick with what you know.

Just my 2 cents.

Charles
 
If poly works for you and you're happy with the results, then that's the best method.

It's always nice to play around and experiment with other techniques, but when it really matters, stick with what you know.

Just my 2 cents.

Charles
Normally this is correct - never change a running system :). But if I want or have to give my model a certain impression or color, because that's how it looked in reality, I cannot avoid a broader level of knowledge. Or I just build a "fantasy ship".;)
 
Normally this is correct - never change a running system :). But if I want or have to give my model a certain impression or color, because that's how it looked in reality, I cannot avoid a broader level of knowledge. Or I just build a "fantasy ship".;)

My apologies if my response left you with the impression that I was discounting the value of knowledge. I assure you that was not my intent.

I realize that context is difficult in an environment like this, but with respect to my response to Daniels post, it was only meant to counter what I perceived as a bit of disappointment on his part that he still only works with Poly.

Your point about building a realistic model or a "fantasy ship" really goes to the heart of the matter, that being what you are trying to achieve.

In the case of the subject of this post, shellac (or finishes in general) on wooden model ships, the Japanese philosophy of "Kaizen", the constant pursuit of improvement, might well apply, especially given that we are still applying shellac in pretty much the same way that it's been done for what, hundreds of years or more?

Just my added 2 cents submitted with due respect to all.

Charles
 
My apologies if my response left you with the impression that I was discounting the value of knowledge. I assure you that was not my intent.

I realize that context is difficult in an environment like this, but with respect to my response to Daniels post, it was only meant to counter what I perceived as a bit of disappointment on his part that he still only works with Poly.

Your point about building a realistic model or a "fantasy ship" really goes to the heart of the matter, that being what you are trying to achieve.

In the case of the subject of this post, shellac (or finishes in general) on wooden model ships, the Japanese philosophy of "Kaizen", the constant pursuit of improvement, might well apply, especially given that we are still applying shellac in pretty much the same way that it's been done for what, hundreds of years or more?

Just my added 2 cents submitted with due respect to all.

Charles
Hello Charles, everything is fine. Probably just a misunderstanding in the idiom. Sorry, it's not my mother tongue, I often have to use Google. As always, there are dozens of opinions on a topic - as long as we can "argue" about it peacefully, that's a fine thing :)
 
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