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 ) all refers to it as an artist's medium, for final coat or mixing paint.

I did find one interesting article 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 ) all refers to it as an artist's medium, for final coat or mixing paint.

I did find one interesting article 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

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, ccliv-viii) ... it has been pointed out that a true amber varnish would work poorly as a varnish for paintings (Toch 1934, 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.williamsburgartconservati...-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/violin...cuoft_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.

black amber from Indonesia.jpg


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

too dark and fractured for jewelry.jpg


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

starting at ambient.jpg


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

15 minutes and first fusion.jpg


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

fusion starts at 399.jpg


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.

fusion progresses.jpg


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'.

surface temp 468.jpg


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?

Tears of amber.jpg


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.

dropwise addition of BLO.jpg


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

the fluffy stuff slowly clears.jpg



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

all melted and dissolved.jpg


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

add stirring bar.jpg


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.

amber varnish version 1.jpg


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

aber varnish dirt.jpg


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

bubinga saw handle for varnish testing.jpg

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.


first coat of amber varnish.jpg

[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.