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Varnish making - questions for the chemists


Jacob

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"Purified" drinking water is not distilled and can have a pretty high mineral content. Distilled water actually doesn't taste very good, although it is possible to get used to it. Distilled water, if done properly, has virtually no contaminants except dissolved air and higher solvent properties than mineralized (including most softened) water. I think that is the point of Oded's request.

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Yes cap'thook's got it. I'd like to know what, if anything, remains dissolved in the oil after washing. Distilled water is a very powerful chemical. For instance I use distilled water (from my de-humidifier) in my aluminum glue pot. This causes the pot to become bright and shiny, everything has been stripped off the aluminum and even perhaps some aluminum has dissolved in the water.

 

I quite certain that this cannot damage the oil. It may even improve it. .And it may have been used by the ancients in the form of rain water

 

de-ionized water is even better if you can find it.

 

Oded 

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de-ionized water is even better if you can find it.

 

I don't believe so..  Lab water distillers have a deionizer before the still, to keep mineral crud from building up in the still so fast, and to keep volatiles (chlorine and organics, etc) out of the boiler, but distillation in glass is still (PI) the gold standard for purity.  "Deionization".  is a filtration step, and trace contaminants get through it. 

 

BTW, there are a number of home water distillers on the market now.  Google "water distiller" :)

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By the way, since we were talking about golden ground and the possibility it was just a very thin layer of varnish, I melt some rosin until it was dark brown put clumps of it on a white piece of paper to follow the coloration. Once the spots were solidified they are very prone to chip and when they do they leave a yellow stain  :)

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By the way, since we were talking about golden ground and the possibility it was just a very thin layer of varnish, I melt some some  until it was dark brown put clumps of it on a white piece of paper to follow the coloration. Once the spots were solidified they are very prone to chip and when they do they leave a yellow stain  :)

That's interesting.   Could a varnish make it's own ground?  In one of my test samples I applied homemade varnish to bare wood.  Now when the varnish flakes off it leaves something in the surface wood fibers.  It is not yellow though. 

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Several people described here how they use their varnish mixed with some minerals (pumice, tripoli etc) as the ground.

Here is the picture of the rosin during cooking and the stain left after it chipped. (I should have simply used some maple or spruce to see what color it would be on wood. But it's definitely yellow/brown on a white paper).

the other thing is that this would fit nicely with the microscopy picture from Echard work where there was no much of a layer between the wood and the varnish.

that is why I am still curious to know if those of you who saw many Cremonese instruments believe there is a golden ground under the fingerboard (or where the original fingerboard was)

post-29661-0-24209500-1374320916_thumb.jpg

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By the way, since we were talking about golden ground and the possibility it was just a very thin layer of varnish, I melt some rosin until it was dark brown put clumps of it on a white piece of paper to follow the coloration. Once the spots were solidified they are very prone to chip and when they do they leave a yellow stain  :)

Robert, it's very common to use a thin layer of varnish or varnish with filler as the last stage of the ground process. It gives a rather slight darkening/ colour enhancing effect, but nowhere near enough to produce the cremonese gold colour.

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Ernie,

No.  There are lots of options.

Joe

I'm re-reading some of the older posts on the subject...so far one option is glycerin but you need a reflux still condenser to avoid the glycerin from boiling off.

hmmm...now who do I know who has a still condenser? just kidding. I guess that ones out of the question.

 

Another option is adding alum to the cook...from an older post... "Bease explains, that the rock alum serves as "a clarifying ingredient used to settle impurities".

Question...If the oil/resin is properly prepared and clarified what other purpose does the alum serve?

 

A quote from Joe..."When using commercial colophony, as Melvin sites, cook with lime or zinc oxide for best results. How much? The normal parameters are 2 - 10%. Geary Bease's observations about liming the linseed oil are accurate for linseed oil but not for varnish....and Geary always used walnut oil....

 

From Geoff...If you add some lime - I use calcium hydroxide - you raise the melting point of the rosin. In a back yard style set up though - as opposed to carefully controlled conditions, its a bit hit and miss - as the temps needed to fully react lime with rosin are up around 280 c.

I've had good results with 5 gms lime to 100 gms rosin - cooked at about 210 c in the rosin for about 40 mins - then about 220 c with the oil added for about the same time.

 

My understanding is the closer to ph neutral the harder the resin becomes. so some acidity is desirable. Also every resin has different acid values so experimentation is necessary to know how much is too much or too little.

 

I don't recall if Roger limed his rosin or not. I'll have to re-read his posts.

 

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