Featured Carved Table or Chair Leg - Origin?

I think there has been a mix up. French polish, shellac, and lacquer are all the same substance, a bug eats the sap of a tree and poops out a hard resin, this resin is cleaned and pulled into sheets and then broken into flakes, this is called shellac. The shellac is then mixed with alcohol/meths to make all 3, French polish, shellac, and lacquer, they are just different names for the same thing. French polish is a product, French polishing is a process, nowhere did I say French polishing, all I said was French polish. French polish, shellac or lacquer can't really be applied in one coat and to my knowledge I have never seen it produce this crazing. I am speaking from 15 years of experience using, stripping, refinishing, French polishing with shellac. The only thing I can think of is maybe the shellac was mixed with wax or oil or both, violin makers used to make a substance like this.

Ok, further research, It seems a varnish was made from oil and pine resin that produces this effect over time, this is a link to a thread of violin makers talking about it so it looks like this "varnish" and the process of making it is the problem
https://maestronet.com/forum/index.php?/topic/320096-severly-crackled-varnish/

 

Ah, so we know the Mercier bridge well....and where to gas up !!

 

I do know what shellac is.

The surfaces that show the type of alligatoring/crazing I am referring to are generally much older than your 15 years of experience. Here are some typical recipes for shellac varnishes, from Varnishes and Their Components, by Robert Selby Morrell, published by Henry Frowde, 1923 :

- Shellac knotting varnish [for sealing wood] – orange shellac 112 lb, medium rosin 56 lb, methylated spirit 28 galls [denatured alcohol]

- Cabinetmakers’ varnish – pale shellac 5 lb, mastic 7 oz, methylated spirit ¾ gall.

- French polish – orange shellac 76 lb, manila resin 10 lb, pale French rosin 10 lb, methylated spirit 50 galls

Looking at several other relevant texts in my library from the first quarter of the 20th century, it is clear that the recipes could be quite variable, and often included additional resins or gums. But shellac (from the lac bug) was the primary ingredient in varnishes used for interior woodwork until the development of synthetic resins in the mid century.

The recommended processes include several steps for the preparation of the wood (filling and sealing), as well as careful instructions for the application of the final layer(s) of shellac varnish. At each step, the authors stress the importance of letting each application thoroughly dry (sometimes for several days) before adding another layer of filler/sealer/varnish.

I suspect the problems of crazing and alligatoring may have resulted from workmen rushing the ideal process, and/or applying too many or too thick layers of varnish. Differential drying of the layers can cause the upper layer to "crawl" over time. Similar unfortunate effects can be seen in some oil paintings on canvas, where the artist disobeyed the rule of painting "fat over lean".

 

"I do know what shellac is" it would seem you don't, all through this thread you have mixed up the product "varnish" with "shellac" ......." It looks like an old shellac coating" "I have seen instances of this type of shellac deterioration on interior woodwork (doors, window frames, baseboards, etc.) before - definitely not high end "French polish" pieces of furniture. It was a simple mixture of lac dissolved in alcohol, painted on as a varnish" "The shellac finish on household woodwork was a simpler process. As noted in the article I linked to, the deteriorated coatings remain soluble in alcohol, indicating this was the original solvent. Shellac was a very common varnish before the development of synthetic resins. I have also seen similar crazing/alligatoring on scientific instruments where tinted shellac was often used as a lacquer coating"
It is only now you use the word varnish as a product "Shellac knotting varnish" "Cabinetmakers’ varnish"
Varnish is different than French polish, lacquer and shellac, some recipes for varnish do include shellac but that doesn't make them French polish, lacquer or shellac.
It would seem like my 15 years of working with shellac did come in handy and oh BTW the pieces I work on that have a shellac finish are up to 200 years old and never result in this type of crazing.

 

Shellac is derived from the excretions of the lac insect. It is processed and refined into sheets which are broken up to create flake shellac. Shellac in this form must be dissolved in a solvent (typically some form of alcohol) to use as a varnish. Shellac is an ingredient, varnish is the product which includes a solvent and, historically, may include other ingredients as well. The terms have often been used interchangeably, although they have more specific technical definitions. The term lacquer is even more problematic - it can mean a solution of shellac, a synthetic resin, or, in Asia, urushi, which is lacquer based on the urushiol oil derived from Toxicodendron vernicifluum.

"French polish" is one form of varnish based on shellac. It is distinguished more by the process of application than by the ingredients. There have been many other varnish formulations using shellac. All I have said is that there have been formulations of varnish, based on shellac, that have been used on interior woodwork that deteriorate in a characteristic way. If you read the link I provided from the Wisconsin Historical Society, it describes this as a known phenomenon. Just because French polish may not deteriorate in this way, it does not mean that other formulations of varnishes based on shellac do not.

I really don't understand your objection to the observation that some forms of shellac varnish deteriorate. In fact, my hypothesis that the fault in these deteriorated finishes derives from poor application techniques would support the superiority of the French polish technique, which relies on multiple thin layers of varnish, dried and rubbed between applications.

My initial comments may not have been as precise as they could have been. I was making a casual observation on the op's object. I did not expect to be writing a dissertation.

Here are some additional references -
https://cameo.mfa.org/wiki/Shellac
https://cameo.mfa.org/wiki/French_polish
https://cameo.mfa.org/wiki/Varnish

 

I did try and say there had been a mix up, to me (and the English speaking world) the term varnish isn't the same as shellac, French polish or lacquer. I wasn't trying to be pedantic or argumentative, maybe it's just the difference between US English and UK English.
For me it was an enlightening thread, I now know far more about finishes than I did yesterday.

 

There is often something lost in translation, including between English and English.

 

It does say something about the chair/table leg 1) the finish is a old one and 2) it was probably made to go outside, I can't see why someone would varnish a inside piece.

 

Often done just to enhance the grain, and provide a "protective" coating.

 

So different, it must just be a European thing. Nothing inside the house here is varnished apart from the backdoor wooden threshold step but wooden items I want to keep nice outside are varnished. Every finished stick of furniture has a non waterproof French polished based finished surface unless it's modern and that has some plastic based finish. It's strange that the US uses varnish inside especially when it's so hard to get a good finish.