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Cooking Colophony Down For Color, Low and Slow?


Berl Mendenhall
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EM, be patient, the varnish will be perfectly clear after several weeks, and will be good for more than just a "ground varnish".

That would be nice. It dries the same as my last batch...one day in the sun and this batch has a longer open time compared to the last one. I left it a little thicker. Does the viscosity need to be thin in order to help it clear? Thanks Jacob!!

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Ernie, italian literature from the 1700`s mention that the ceramic pot must be new to cook varnish, the explanation is,  once taken to a certain temperature the ceramic becomes full of tiny cracks where the varnish lodges in, and ruins your next batch of varnish.

 

My limed varnishes precipitated and became clear in the pot, perhaps a little precipitation in the jar later on, but not too much, it appears to me that once it begins to precipitate on the jar it is better to let it be for a while, because once the varnish has been poured into another jar it appears that precipitation stopped (or it was a coincidence).

 

Once again early literature mentions these sort of varnishes getting better with time, 20 years is mentioned quite a few times.

 

Good luck!!

Carlo

I found the info in the old literature about ceramic pots very interesting. I finally had a chance to do some research into vitreous enamel cookware. In a nutshell most enamel coated metal cookware can develop cracks when cooked at high temperatures. I did find one company who claims that there enamel can handle higher temperatures...Xtrema ceramic cookware. I am going to replace my pot and will try one of these modern ceramic pots. I don't know if it work on an induction cooktop. I need to do more research. Thanks again for posting that information.

http://the-ceramic-cookware.com/xtrema-ceramic-cookware

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Hello all,

I have been "side-lined" for a while, but I have kept up with this topic. 

A few thoughts....

As usual, I am reminded that there is no magic bullet.  No one temperature, cook time, resin, rosin or balsam that will produce the perfect color and clarity every time you cook it.  As with the rest of this trade, it is more complex than that.  I make 13 rosin/raw pine resin/larch resin varnishes.  There are 4 different "resins" and 7 different cooking [resin preparation] methods for that group of varnishes.  Makes me glad that part of my research is in the past!  So if you are to find the proper method and material for making your own varnish: get lots of the raw material and take good notes.

 

If you are adding lime in some form to the resin cooking and the final product is cloudy:

1 the cook is incomplete

and/or

2 the amount of lime is wrong for the resin

and/or

3 there is another mineral in the lime like excess calcium or magnesium.

but...when the process is correct the resin is clear and bright...

 

If the final varnish is cloudy and the material settles out then the varnish is probably fine to use...but the next time you make it correct the cooking so the varnish is clear from the start.

 

on we go,

Joe

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Ernie, glad you found it, and thanks for the tip on the Xtrema, very interesting, I could not find it but maybe you did, how high a temperature before cracking...or may need to call the company, it may be a great solution, even if only for the low/med temperature varnishes.

 

Joe, thanks for the clear and experienced opinion.

 

:)

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Peter

 

Increase the color (as in the photo) when you apply the first coat.

A single coat of varnish with pigments (burnt sienna, burnt umber, dark red madder).

3 coats of clear varnish to finish.

 

www.kreitpatrick.com

 

Thanks. It's incredible how dark the varnish/colors have to be! Roger have also pointed this out many times here and in his double bass thread.

 

I think my grounding this time got too dark (more UV and Casein/lime mix to change the color) to get that kind of result.

 

post-37356-0-49721900-1405932628_thumb.jpg

 

Second coat with lots of more colors and it could have been even more

 

post-37356-0-18815700-1405933790_thumb.jpg

 

 

 

 

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Thanks. It's incredible how dark the varnish/colors have to be! Roger have also pointed this out many times here and in his double bass thread.

 

I think my grounding this time got too dark (more UV and Casein/lime mix to change the color) to get that kind of result.

 

attachicon.gifpost-38156-0-38922100-1405875252.jpg

 

Second coat with lots of more colors and it could have been even more

 

attachicon.gif2014-07-21 11.16.11.jpg

Looks great, are you going to scuff it up an ancentify it?

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Carlo

I found the info in the old literature about ceramic pots very interesting. I finally had a chance to do some research into vitreous enamel cookware. In a nutshell most enamel coated metal cookware can develop cracks when cooked at high temperatures. I did find one company who claims that there enamel can handle higher temperatures...Xtrema ceramic cookware. I am going to replace my pot and will try one of these modern ceramic pots. I don't know if it work on an induction cooktop. I need to do more research. Thanks again for posting that information.

http://the-ceramic-cookware.com/xtrema-ceramic-cookware

Ernie,

A ceramic vessel won't work on an induction cook top. You need to have a conductive  pot that the induction cooktop can induce eddy currents into , thus creating the heat. You could put a block of iron into the ceramic vessel, but it probably wouldn't work very well because of the inverse square law magnetism losses. The iron should be in intimate contact with the cooktop surface to avoid this.

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Ernie,

A ceramic vessel won't work on an induction cook top. You need to have a conductive  pot that the induction cooktop can induce eddy currents into , thus creating the heat. You could put a block of iron into the ceramic vessel, but it probably wouldn't work very well because of the inverse square law magnetism losses. The iron should be in intimate contact with the cooktop surface to avoid this.

Interesting Bill. Are you familiar with the Xtrema ccokware? From what I have read the cookware is made of metal and ceramic. But nothing mentioned if it will work with an induction cooktop. My current cookpot is enameled cast iron and it works fine on induction. I think if a magnet sticks to the bottom of the pot it will work on induction. However I don't know enough about the new Xtrema cookware or how it is made. I have always liked cooking in the LE CREUSET cookware and haven't ever noticed the inside of the pans cracking until Carlo mentioned it. I still don't really understand how that would spoil the next batch of varnish either. If the modern ceramic cookware can handle temps above 500F then I'll give it a try. And if it doesn't work on an induction cooktop that's OK too. I'm looking to buy a laboratory hot plate that will get above 500F. This last batch of limed rosin varnish only got to 480F and my cooktop was at the highest setting which is 575F. It would go to 500F if I kept a lid on it.

Can you recommend a lab hot plate? As you know the last one I bought wasn't a hotplate at all. I really don't know anything about them or what kind to purchase. Electronics is not my cup of tea.

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What really makes the laboratory hot plate useful is having an external temperature probe that can be immersed in the sample. Then you can control the temperature much more accurately. It's tricky because sometimes the temperature probes can be as expensive as the hot plate. In my searching I haven't found a probe that will go much over 200 C. There are plenty of hot plates that will go higher, just look for the rated temperature or wattage rating.

I've been able to run copal at 400 C with a 1500 watt hot plate from Fred Meyer. But when I'm doing a low and slow cook I have a Dataplate 730 series laboratory hot plate with a temperature probe which I bought on eBay.

Personally I like to cook in stainless pots, or in Visionware glass cookware. The Visionware is rated to 400 C and can be cheaply bought at thrift stores. I like the idea that the glass is completely non reactive. I've only ever had one break and that was because of user error.

Michael

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Interesting Bill. Are you familiar with the Xtrema ccokware? From what I have read the cookware is made of metal and ceramic. But nothing mentioned if it will work with an induction cooktop. My current cookpot is enameled cast iron and it works fine on induction. I think if a magnet sticks to the bottom of the pot it will work on induction. However I don't know enough about the new Xtrema cookware or how it is made. I have always liked cooking in the LE CREUSET cookware and haven't ever noticed the inside of the pans cracking until Carlo mentioned it. I still don't really understand how that would spoil the next batch of varnish either. If the modern ceramic cookware can handle temps above 500F then I'll give it a try. And if it doesn't work on an induction cooktop that's OK too. I'm looking to buy a laboratory hot plate that will get above 500F. This last batch of limed rosin varnish only got to 480F and my cooktop was at the highest setting which is 575F. It would go to 500F if I kept a lid on it.

Can you recommend a lab hot plate? As you know the last one I bought wasn't a hotplate at all. I really don't know anything about them or what kind to purchase. Electronics is not my cup of tea.

I don't really know much about hot plates and such, just the principle of how the induction cook top works. I don't know why microscopic cracks (or even larger cracks) in the ceramic would be deleterious to the varnish. The cracking is due to the different expansion rate between the iron and the ceramic enamel.

 

I would guess than an iron vessel with a thin enamel would work fine on the induction cooker.

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Personally I like to cook in stainless pots, or in Visionware glass cookware. The Visionware is rated to 400 C and can be cheaply bought at thrift stores. I like the idea that the glass is completely non reactive. I've only ever had one break and that was because of user error.

Michael

I had a pyrex container break on me once with hot varnish in it. Nothing terrible happened aside from having to try and save the lost varnish, but the potential is there for a dangerous situation. I would try and keep away from glass ware if possible.

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I had a pyrex container break on me once with hot varnish in it. Nothing terrible happened aside from having to try and save the lost varnish, but the potential is there for a dangerous situation. I would try and keep away from glass ware if possible.

Fair point. That is why stainless is my second choice, because I know it won't break.

The visionware is pretty tough stuff.

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 A friend gave me a thermometer he bought from Harbor Freight, don't what it costs but it is  professional grade. It is battery operated, reads in O,F, or K. I don't have the range but I'm certain it is adequate since I've gone into hi 600's  with copal. It has a ca 2foot thin wire to a thin glass probe. The only data I have is:   CEN-TECH    model no  92242      Digital thermometer with K type probe. Unless the price is outrageous it is well worth it.

  fred

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ceramic is for a non reactive cook (is reactive the right word?), the only reason I would use it (I do not know if tin glazed pottery releases some of the tin into the cook), so many recipes asking for a new pot, why? from what I read in one book, reason being the tiny cracks develop and the varnish loges in, so next time you cook (unless you do some very thorough cleaning) your next batch of whatever will get a little of the left over varnish or color you cooked before, not being a non reactive cook anymore, so why use ceramic in the first place?  (unless you want the tin, or the leftovers)

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A friend gave me a thermometer he bought from Harbor Freight, don't what it costs but it is professional grade. It is battery operated, reads in O,F, or K. I don't have the range but I'm certain it is adequate since I've gone into hi 600's with copal. It has a ca 2foot thin wire to a thin glass probe. The only data I have is: CEN-TECH model no 92242 Digital thermometer with K type probe. Unless the price is outrageous it is well worth it.

fred

I bought an infrared thermometer from Harbor Freight and it was wildly inaccurate. That and other disappointing products there have led me to the conclusion that professional grade and Harbor Freight don't belong in the same sentence.

I have a glass mercury thermometer, 0-400C, that I bought from some laboratory supply company. Not even that expensive, as I recall.

Michael

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Depends what you are looking for!  I bought their small F clamps for $2.99/piece, and they are fantastic.  Anything with electronic or mechanical complexity is another matter.  When the same clamp cost $18 anywhere else, however, I will advocate for Harbor Freight.

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Hi Michael- I don't know anything about such a thermometer. I used a mercury and the digital thermometer concurrently  and there was a constant discrepancy I'm certain due to the sensor in the probe being at the very bottom of the probe, and the mercury in the bulb  further away from the bottom due to vertical shape, reading the temp of the contents. I don't think you have to use it very long  to appreciate it. I've bought a lot of stuff from them and I guess I've been lucky re price and quality. fred

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