Madder Alum Rosinate


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1 minute ago, Don Noon said:

I haven't had much luck cooking the alizarine rosinates into oil... but I have been using the higher alizarine concentrations.  I tried dissolving the rosinate into a solvent, mixing with oil, and then cooking the solvent out, but the rosinate wanted to fall out of solution too.  Perhaps the lower concentration would cook better.

I remember you mentioning that, maybe in the iron rosinate topic (incidentally the topic that set me down the rabbit hole). I was using the standard 15% solution of alizarin, seems plenty colored to me. I also didn't cook it that hot, all things considered - 120°C. I got this figure from John Geddes Macintosh's book.

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22 hours ago, Andreas Preuss said:

This makes me really curious because I have seen long ago I. think it was a Tononi cello which had this kind of detachment.

So if I understand correctly hot varnish is cooking resins and oil for a very long time. Cold 'varnish' is the resinate type of thing?

 

"Cold mix" is combining oil and rosin without heating needed to induce molecular  crosslinking. If you heat a Michaelman rosinate,  it deteriorates. So that is why he did a cold mix. 

 

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Michael, if you would be so kind, please say more about the deterioration of rosinates under heat. I know Nunzio doesn't use the cold mix method, so I assume he does some kind of cooking. I have also been cooking rosinates, as of course has Don. I got the cooking technique from the book I mentioned in my previous email post, now in the public domain. The relevant section, note the proposed use for rosinate varnishes:

Preparation of Rosinates. — A rosin soap is made by heating 100 parts of pale rosin with 33 parts of soda crystals in 1,000 parts of water, and adding to the solution cooled to 50° a solution of colour ing matter ; a solution of a metallic salt is then added such as the chloride of magnesia, and the solution is filtered from the insoluble coloured resinate which is well washed and dried at a very gentle heat. The dried product constitutes in reality a true coloured lake. For toys, tin boxes, etc., cheap and quick-drying varnishes are re quired, and in the preparation of these the resins and even common rosin have been replaced by rosinates which dissolve readily in warm linseed oil, and some of these, more especially the resinate of zinc in particular, is very durable. These rosinate varnishes are made by dissolving the rosinate in linseed oil heated to about 120° C. and then diluting with the necessary quantity of spirits of turpentine. The resinates most usually employed are those of lead, zinc, man ganese and lime. A great number of aniline dyes being soluble in solutions of certain rosinates, coloured rosinate varnishes may be made of any desired hue. Fused rosinates are made by heating rosin with metallic oxides (e.g., what is called hardened rosin is made by heating rosin with quick-lime ; the product will dry better if a little manganese be stirred in at the same time).

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2 minutes ago, Michael_Molnar said:

The deterioration, I thought, is explained in Michaelman's book. There is an electronic google version. Look for it, if you do not have the hard copy. I'm not at my computer where I keep that link. Anyhow, I presumed he was right and never tried cooking them. 

I've got a copy, which I have read many times, and yet missed this. It happens! I'll look again when I get home from my wife's concert

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Upon returning home and revisiting my copy of the book, the only references I can find to decomposition are in the section Other Resins and Soaps, and don't refer to rosinate varnishes. The first describes that benzoin doesn't hold up well to cooking, the second relates to the necessity of some measure of decomposition in the process of cooking unmodified rosins into oil. 

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On 12/6/2018 at 10:37 PM, JacksonMaberry said:

Upon returning home and revisiting my copy of the book, the only references I can find to decomposition are in the section Other Resins and Soaps, and don't refer to rosinate varnishes. The first describes that benzoin doesn't hold up well to cooking, the second relates to the necessity of some measure of decomposition in the process of cooking unmodified rosins into oil. 

The second paragraph in Chapter XVI (p. 149) explains that his wet process avoids the high temperatures of dry fusion that will decompose (most) organic colors. This is why he uses the wet process.

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1 hour ago, Michael_Molnar said:

The second paragraph in Chapter XVI (p. 149) explains that his wet process avoids the high temperatures of dry fusion that will decompose (most) organic colors. This is why he uses the wet process.

Michael,

The section you reference deals with preparing the rosinate itself, not a rosinate varnish, which is what you mentioned with regards to the use of heat in this subject. 

Edit: the temperatures used in dry fusion of rosinates greatly exceed the temperature McIntosh lists for cooking rosinates into oil.

On 12/6/2018 at 7:19 PM, Michael_Molnar said:

"Cold mix" is combining oil and rosin without heating needed to induce molecular  crosslinking. If you heat a Michaelman rosinate,  it deteriorates. So that is why he did a cold mix. 

 

 

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4 hours ago, JacksonMaberry said:

Michael,

The section you reference deals with preparing the rosinate itself, not a rosinate varnish, which is what you mentioned with regards to the use of heat in this subject. 

Edit: the temperatures used in dry fusion of rosinates greatly exceed the temperature McIntosh lists for cooking rosinates into oil.

 

McIntosh temperatures?

Cook some up with alizarin or cochineal and tell us what you get.

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On 12/6/2018 at 4:26 PM, JacksonMaberry said:

I'm intrigued by the rosinates and have experimented with them to a small degree. I would like to do so further! I have used chlorine salts, called for in Michelmans later addendum, rather than sulfates. I can't comment on aluminum rosinates because either have never made any! I have made iron rosinate using a ferric chloride  precipitant and, like Don Noon, find it to be a nice reddish brown when cooked into linseed oil at a rate of 1:1 by mass. 

I have made alizarin rosinates using a zinc chloride precipitant and a zinc chloride/ calcium chloride precipitant. The former came out a cooler hue and the latter a hotter one. In both cases, I found that the longer I cooked the alizarin rosinate in the oil, the deeper the color became. If one keeps going it turns ugly. The best color I got in this way was with the Zn/Ca precipitant and cooking just until it began to pass from crimson into "blood". 

As regards stability or adhesion over time, I can't comment yet. These varnishes we're all cooked within the last six months. 

Michael, I'm sorry to repeat myself, but this is all from this very topic.

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Looks nice. However, I did not see that you were cooking at low temperatures. I go up to 290 C to get the foaming action that cross linking produces. Some makers add the rosinate after cooling to a lower temperature like yours.

Again, nice varnish. Are you happy with it on a violin?

Edited by Michael_Molnar
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4 minutes ago, Michael_Molnar said:

Looks nice. However, I did not see that you were cooking at low temperatures. I go up to 290 C to get the foaming action that cross linking produces. Some makers add the rosinate after cooling to a lower temperature like yours.

Again, nice varnish. Are you happy with it on a violin?

Thanks. I havent tried the alizarin varnish on any fiddles yet, as I'm not fond of red. I made it just to see if I could. I did put a couple very thin coats on top of some iron rosinate varnish made in the same way, which looked kinda nice but still too red for my taste. I will see if I can locate that particular chip of maple and post a photo.

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I recently dissolved rosin in alkaline solution and precipitate with Fe SO4. Air oxidises the Fe2+ quickly to Fe3+ which so redbrown. I added a little rosin and cook this briefly together, then added an equal amount of linseed oil and heated this for one hour. I get a relatively hard sticky substance that dissolves in turpentine.

20181212_115937.jpg

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22 hours ago, JacksonMaberry said:

I will give that a shot. I've considered making some green copper rosinate varnish, just for giggles. 

To darken a color you need to add its complementary color. The ideal complement for red madder and  cochineal lies around turquoise. Your copper rosinate should do the trick. Have fun. I'm looking forward to your results.

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On 12/5/2018 at 9:08 AM, Don Noon said:

If you do the Michelman cold solvent method, you eventually get islands of varnish with wide expanses of bare wood between them.  I think it's probably more related to the cold solvent method, rather than the resin itself.  I have tested iron rosinate cooked in oil (no other resins), and so far it seems very hard and stable, after a few years on glass.

Don has recalled an important issue.  A number of years ago, John Masters revealed what time had done to the Michelman varnish.  It shrinks, cracks, falls off etc.  I think John lives in Cincinnati and saw first hand what age does to the varnish (and reported it on Maestronet).  Michelman lived in Cincinnati  and published his book in 1946; so plenty of time has gone by.  In other words, the Michelman varnish is unstable.

Is the Alizarin you are using really alizarin crimson (which is already a lake)?   

Why not look at the quinacrodones--they are very light resistant.  Since you are already getting away from what the Italian masters used, you might just as well look at a pigments which could never have been used by the masters since they were invented about 60 years ago.

Mike D

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8 hours ago, Mike_Danielson said:

Don has recalled an important issue.  A number of years ago, John Masters revealed what time had done to the Michelman varnish.  It shrinks, cracks, falls off etc.

.....

Oh, my God!!

What about bad execution?

I used the Michelman varnish, following the book closely, for many years from ca. 1988 and on. That's quite long ago. The only serious deficiency that I find with it, and the reason I stopped using it, is tackiness.

Michelmans impregnation with linseed oil, however, was probably a failure. I think this may be the cause of the roumours here on Maestronet about his varnish. 

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1 hour ago, Salve Håkedal said:

Oh, my God!!

What about bad execution?

I used the Michelman varnish, following the book closely, for many years from ca. 1988 and on. That's quite long ago. The only serious deficiency that I find with it, and the reason I stopped using it, is tackiness.

Michelmans impregnation with linseed oil, however, was probably a failure. I think this may be the case of the roumours here on Maestronet about his varnish. 

I share your perplexity, I have enough experience to know that the same varnish applied differently, with different dilutions, different thicknesses of the layers, different drying times between layers and all others possible variables in the application process can give very different results, from the perfect varnish to the worst aligatoring.
So it is difficult to make absolute claims based only on a couple of cases, even if reported by reliable and experienced people.
 
Having said that, also in my opinion it is not a good idea to follow Michelman's book to the letter, but the basic ideas are not to be thrown away.
I also suspect that the causes of the bad alligatoring  can be found otherwise, for example if the impregnation with oil suggested by the book was used as a ground, it could be this to have caused problems and not the varnish itself, or insufficient drying time between layers or a too thick layer or......or.....or......:rolleyes:
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