Amber varnish

[rob streeper]

Has anybody made amber varnish? I'm tooling up to give it a shot and would appreciate hearing from anybody who's made some.

[rob streeper]

Nyits? Nobody? Guess I'll have to go it alone then. Results posted here later.

[Skew ChiDAMN!!]

You've piqued my curiosity here! What do you plan to use it for?

The only 'amber varnish' I can find (google is my friend :D) all refers to it as an artist's medium, for final coat or mixing paint.

I did find one interesting article (http://www.conservation-wiki.com/wiki/II._Traditional_Artists'_Varnishes) but it concludes with “It is known in the trade that only a very small quantity sold under this name really contains amber at all” (Hurst 1922, 409).

[rob streeper]

You've piqued my curiosity here! What do you plan to use it for?

The only 'amber varnish' I can find (google is my friend :D) all refers to it as an artist's medium, for final coat or mixing paint.

I did find one interesting article (http://www.conservation-wiki.com/wiki/II._Traditional_Artists'_Varnishes) but it concludes with “It is known in the trade that only a very small quantity sold under this name really contains amber at all” (Hurst 1922, 409).

I'm planning on using it on my saw handles. I've Googled around and found amber varnish also has been and is used on violins and other stringed instruments. There are some recipes available that, in a nutshell, involve melting the amber (~300 oC), pouring off the liquid onto a metal plate, then dissolving the congealed material in heated linseed or walnut oil. Alternatively amber is dissolved directly without fusing, again at ~300 oC, in one or the other of those oils. Apparently pretty tricky as the auto-ignition temperature of the oils is just a few degrees above 300 oC. I'm planning an experiment wherein amber will be heated in linseed oil with stirring under argon and refluxed for a time. Pending the results of that exercise I'm planning to use Soxhlet extraction to dissolve the amber. I just received 5 lb of very dark Indonesian amber as a test article.

[ian]

could you use CO2 or Nitrogen as you O2 shield?

[rob streeper]

could you use CO2 or Nitrogen as you O2 shield?

Probably, I have a tank of argon for TIG welding so for me it's a convenience.

[ian]

this has piqued my interest also.

a bit of googling found

http://www.conservation-wiki.com/wiki/II._Traditional_Artists'_Varnishes
(http://www.conservation-wiki.com/wiki/II._Traditional_Artists'_Varnishes)
There are many old recipes for amber varnish, but there is some question about whether amber was distinguishable from hard copal resins, and whether such a valuable material as amber would have actually been used in a varnish (Merrifield 1849 (http://www.conservation-wiki.com/wiki/II._Traditional_Artists'_Varnishes#ref35), ccliv-viii) ... it has been pointed out that a true amber varnish would work poorly as a varnish for paintings (Toch 1934 (http://www.conservation-wiki.com/wiki/II._Traditional_Artists'_Varnishes#ref50), 149–50)

so it is likely that the traditional "amber varnish" as used in the 17th century was named for the colour rather than the use of fossilised amber -- perhaps "amber" referred to the colour and the varnish was actually a copal varnish

http://www.jamescgroves.com/copalvarnish.htm
Our "19th Century Copal Varnish" is similar to our "16th Century Amber Varnish", though it is formulated with the very same copal that has been common to European varnish makers and artists since before the time of Columbus.


http://www.williamsburgartconservation.com/historic-varnishes-and-resi.html
Varnish Resins
Resins are often confused with gums and many historical documents and recipes used the terms interchangeably.

Copals: a resin from ancient, extinct Dipterocarpaceae trees. This semi-fossilized resin was historically dug from the ground. The resin ranges from soft copals, soluble in alcohol, to harder Zanzibar copals, which need heat to fully disperse them, to amber, a fully fossilized resin. Copals are found around the world. Used in both spirit and fixed-oil varnishes.





I'm interested in seeing / reading your results -- just don't burn the shed down.

[rob streeper]

Here's some things I've found.

http://www.archive.org/stream/violinvarnishhow00foucuoft/violinvarnishhow00foucuoft_djvu.txt

http://alchemistmediums.com/products_instrument.php

http://www.oldwood1700.com/ficha.aspx?id=6

[Skew ChiDAMN!!]

Thanks for the info, Rob. Your first link has some interesting reading!

I'll be pulling up a seat for this one. :)

[rob streeper]

I got a little time today to mess about with this project.


Now for the mandatory safety warning: Don't do this, the temperatures are high and the chance of fire is great.


On reflection I realized that the original makers of amber varnish didn't make use of inert gas blankets so I decided to give the process a go without Argon.


First the test material. This is black amber, available at a good price on eBay.

359483


Pretty ugly stuff in reflected light but transmitted light reveals something more.

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I placed a small chunk in a beaker and started heating.

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At 15 minutes I noted that fusion had begun. This may be the so-called amber oil forming.

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Hard to get an accurate read on temperature but this seemed pretty consistent.

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Like most natural products amber has a fairly wide fusion temperature range. A little while after the above picture the temperature was nearing 500 oF.

359482


As fusion progressed I slowly added more pieces of amber until I had about 125 ml of fused material. The melt temperature seemed to stabilize around 470 oF or so. Solids were still present at this temperature. I suspect that the solids are what was called 'amber colophony'.

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I let the melt stand and cook for a while under cover and I noticed a ring of condensate about midway up the beaker, Tears of Amber? The smell was very earthy with a hydrocarbon undertone, is this what the dinosaurs smelled?

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After about 30 minutes it was clear that nothing else was happening so I decided to start adding boiled linseed oil to the melt. Dropwise and with great care of course.

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As I added BLO the material floating on top of the melt dissolved. This observation is consistent with the amber oil / colophony literature.

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I added in ~125 ml of BLO and all solids had apparently dissolved.

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I decided to let it cook with stirring and I added in a Teflon coated stirring bar.

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To be continued...

[rob streeper]

I was able to work on this some today. In doing some more reading and thinking on the subject I decided to make the first batch up using fused whole amber. The workflow was.

amber(s) --600 oF--> amber(l) + linseed oil (l) --500 oF--> Solution A


Solution A is composed of 50% v/v amber in linseed oil. Solution A forms a thick suspension on cooling, far too thick for use as varnish. Following the breadcrumbs on the subject available online I re-heated Solution A to ~500 oF.

200 ml of gum turpentine was warmed in a water bath to ~180 oF. 200 ml of Solution A was slowly added to the warm turpentine keeping the solution just below the boiling point. Final composition 50/25/25 (v%) turpentine/linseed oil/amber.

The solution was filtered hot through cheesecloth to remove dirt.

Here's the product.

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There was a surprising amount of insoluble material in the amber.

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I decided to test it's performance on this saw handle.

360090

More later.

[rob streeper]

I finally got back to this project today. I've been making a saw for a customer using a nice piece of very hard rosewood and decided to give the amber varnish a shot.
I've made some modifications to my preparation procedure. I made this batch by fusing some amber, scooping out the lighter colored chunks that I think are referred to as 'amber colophony' in the various links posted above, then I take the dark brown melt and dissolve it in turpentine. I went through several application methods and dilution factors and this is the product at the end of the day. The film build and gloss are great, I've got to do something to slow the setting of the coating that will allow for better leveling.


362028

[soundman]

Have ya thaught of just disolving the amber in thinners.

Just throw a few lumps in a jar of thinners and see how it goes.

I did some work on Black Japan some years ago ...... I did a small batch more or less to tradition, disolve the asphaltum in turps, disolve the shelac in meths, mix both together and add linseed oil ...... ahh just chucking the asphalt, shelac flakes and linseed oil in with some thinners worked better.

OH no need for gum terpentine ...... spare ya brain cells, white spirit or mineral turps will do the same job.

cheers

[soundman]

You'll probaly find amber would have been replaced with beetle droppings when trade opened up with the middle east and shelac became the resin of choice for many things.

cheers

[rob streeper]

The melting process is referenced in the historical materials cited above as necessary because the heat alters the amber destructively, i.e. after melting you don't have amber anymore. Fusion is also the only practical means of separating the colophony from the oil.

Turpentine is listed as the only useful solvent. I haven't tried mineral spirits but the references I've reviewed say that it doesn't work. For the record, mineral spirit is dangerous too (neurotoxic).

Amber varnish is preferred by some luthiers, particularly those that make violins.

[rob streeper]

The first saw completed with this finish is here: http://www.woodworkforums.com/showthread.php?t=198312&page=3
I rubbed this handle with rotten-stone to produce a satin finish per customer specification.

[D.W.]

Under the weather and taking the afternoon off both with the flu and a migraine. But not good at laying in one spot, so looked up amber varnish for a reason that I can't now recall. I think to see if anyone had successfully cooked it.

Rob are you still around?

I cooked amber varnish in 2023, approximately 45% resin and 55% linseed and then thinned with about 12 oz of turpentine. ....oh, and the resin and oil were about 20 oz total after cook.

I think to claim you made amber varnish is mostly seen now as not credible, but I made 16 batches of varnish last year and by the time I got to amber, I'd sawed through a couple of very high melting point copals, one of them with dirty resin and amber in pencil eraser size bits was actually easier.

The key to the run was tolerating 650-700F temperatures on the thermocopule at the bottom of the pot, letting the cook go wherever the behavior of the resin said it needed to be, and then as the resin darkened but was stable, truncating the run and leaving the 10% or so of the resin that didn't want to melt alone to be strained out. Put simply, trying to get all of that melted would ruin the rest.

I doubt anyone is interested in the process I followed, and it is dangerous. Running baltic amber is also the smelliest thing I've ever encountered in my life, and I did actually get knee deep in a hot summer dumpster at a high school job, and have smelled "in your face" half rotted animals. the smell of the resin running is so bad that a day after I did it 50 feet from my house, I hung outdoor lighting for a completely unrelated issue and the gutters of the house stunk like amber when I got on the ladder. It is the worst smell I've ever encountered, bar none, choking and gagging and heaving if you accidentally get a small whiff of the smoke.

As soon as its' ready for linseed oil, if you can get the oil in it, that smell is gone.

I have the better part of a quart when all is said and done. it's about 65% solid, maybe a little more as the turps boils a little bit when added late in the cycle and some of it probably cooks off. You thin the varnish with more turpentine when making some to use, and I pour off something like 4 ozs in a separate jar and add drier. That batch will probably be unfit for use in 2 years, but the full jar from the run that does not have driers should outlive anyone on this board by far.

ALCHEMIST™ Amber Varnish Clear in linseed oil Mediums, Binders & Glues | Kremer Pigments Inc. Online Shop (https://shop.kremerpigments.com/us/shop/mediums-binders-glues/79900-alchemist-amber-varnish-clear-in-linseed-oil.html)

My varnish is almost a 1 to 1 ratio resin to oil, and kremer's is a much easier to get to look good 1 to 4 ratio. A softer and less hard varnish will result, but given it's amber, it's probably still fine.

the price is astronomical. I've seen other violin varnish makers who are doing it as cottage industry charge $1 per ml.

In my county, it is not legal to make varnish and sell it without setting up a cookery hood with a 1000F or something gas flue temp to burn off the stinky volatiles mentioned. So hobby is all it will be.

that said, most of the stuff for violin use seems to be long oil, which looks lighter in color. I suppose it would be possible for me to take this batch, put it back in the pot and boil off the turps and add more oil, but I want it hard.
https://ofhandmaking.files.wordpress.com/2023/08/wp-1691537555381.jpg

The when the resin total is higher, the varnish is very dark - an orangey color a little bit.

The look of the film on the side of the jar shows what it looks like unthinned.

https://ofhandmaking.files.wordpress.com/2023/08/wp-1691537640169.jpg

On louro preto (color similar to rosewood), it looks like this with a thin coat - the varnish when dry is extremely hard with a ridiculously high melting point compared to modern finishes, and it's waterproof before it's even fully dry, and very solvent and abrasion resistant.

it is not as user friendly as something like a good quality lacquer, though, but like the non-dryer store that remains in the jar, the applied finish should outlast anyone here if applied to furniture.

Makes a great quick and dirty wipe on finish for a chisel handle, though, and should also make a knife handle that would not be harmed by an accidental cycle in a dishwasher.