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Cooking Colophony Down For Color, Low and Slow?


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Are you going to try and lime some of your raw resin Don? I would love to hear if it works for you. I have a lot of the Abies Alba resin I would like to use but it makes a too soft varnish. If you get good results please post your method of incorporation and results.

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In a linseed oil/pine rosin varnish, I think the rosin acidity will need to be brought down somewhat to keep it from eventually altering and corrupting the oil component. I've had things go downhill as quickly as within a year.

 

I'm not a chemist, so that's just my theory on what happened. Rosin alone seems to be decently stable.

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In a linseed oil/pine rosin varnish, I think the rosin acidity will need to be brought down somewhat to keep it from eventually altering and corrupting the oil component. I've had things go downhill as quickly as within a year.

 

I'm not a chemist, so that's just my theory on what happened. Rosin alone seems to be decently stable.

How do recommend bringing it down?

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Thanks for the bit of advice David. Would you incorporate the lime in the same way EM did? By mixing slaked lime with water and adding that to the cook?

The resin I will try it on is some spruce resin ( sap, oleoresin, balsam, pitch, whatever you want to call it) that I have collected from the trees and cooked it into a dark resin, it resembles dark rosin at this point. It has a low Tg so I need to bring it up or harden it so to speak.

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EM, I will try to lime some but at a later date when I have some free time. At this point though it is no longer a raw resin it has been cooked some.

I have both raw and cooked Abies Alba. Please share your results when you get around to it.

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How do recommend bringing it down?

My only experience is with lime, so there may be better ways which I haven't tried. Maybe Quinn can shed some more light on this and other options.

 

Thanks for the bit of advice David. Would you incorporate the lime in the same way EM did? By mixing slaked lime with water and adding that to the cook?

 

I've only tried slaked lime for casein coatings/glue, and powdered for varnish. I don't know what the difference would be for varnish, except that maybe the water content of the slaked lime would make it a little bit more dangerous when adding it to hot resin.

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Thanks for the bit of advice David. Would you incorporate the lime in the same way EM did? By mixing slaked lime with water and adding that to the cook?

The resin I will try it on is some spruce resin ( sap, oleoresin, balsam, pitch, whatever you want to call it) that I have collected from the trees and cooked it into a dark resin, it resembles dark rosin at this point. It has a low Tg so I need to bring it up or harden it so to speak.

 

 

My only experience is with lime, so there may be better ways which I haven't tried. Maybe Quin can shed some more light on this and other options.

 

I've only tried slaked lime for casein coatings/glue, and powdered for varnish. I don't know what the difference would be for varnish, except that maybe the water content of the slaked lime would make it a little bit more dangerous when adding it to hot resin.

 

 

I use slaked lime for both.

 

Maybe you would like to try this? Add slaked lime to warmed linseed oil before you add it to the cooking rosin

 

 

Recipe

http://www.thestradsound.com/home/varnish

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I use slaked lime for both.

 

Maybe you would like to try this? Add slaked lime to warmed linseed oil before you add it to the cooking rosin

 

I don't know if I'd like to try it. My goal has been to react the rosin separately, before it has contact with the linseed oil.

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In my adaptation of Keith Hill's recipe I pour distilled water through ashes and add this water to the oleo resin (balsam etc) to saponify it. The acidic linseed oil is then added to make a neutral or slightly acidic varnish. One of the supposed advantages is that wood ash contains lots of trace metals which act as driers in the varnish. 

I've moved away from this recipe partly because of the uncertain nature of the constituents of the wood ash, although in fact I've not had any problems with the vanish I've made using this method.

I should also add the disclaimer that I'm not a chemist.

 

Oded

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Thanks for the bit of advice David. Would you incorporate the lime in the same way EM did? By mixing slaked lime with water and adding that to the cook?

The resin I will try it on is some spruce resin ( sap, oleoresin, balsam, pitch, whatever you want to call it) that I have collected from the trees and cooked it into a dark resin, it resembles dark rosin at this point. It has a low Tg so I need to bring it up or harden it so to speak.

Don, 

Will this be the resin collected in Maine, presumably from red spruce?  I will be interested to see the results.

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Don, 

Will this be the resin collected in Maine, presumably from red spruce?  I will be interested to see the results.

Yes, that's it. I posted a couple pics about halfway through this thread, I had two batches, one dissolved and filtered with alcohol ( prior to cooking) and one with turps. Since the alcohol one won't mix with turps it's not a possibility, the one using turps I just need to make the cooked resin harder or have a higher Tg. ( transitional glass temperature) So I'll cook some lime into it to see what it does.

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In a linseed oil/pine rosin varnish, I think the rosin acidity will need to be brought down somewhat to keep it from eventually altering and corrupting the oil component. I've had things go downhill as quickly as within a year.

Hi David, What sort of things happened with the varnish? -em

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Hi David, What sort of things happened with the varnish? -em

With time, It became extremely brittle, and I'm pretty sure it started to become a lot darker too (been a while since I experimented with it).

 

Not saying that's necessarily bad, but it's not what I was looking for. I like things to stop changing once their applied and dry. Part of that is because I want the tone to be stable.

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With time, It became extremely brittle, and I'm pretty sure it started to become a lot darker too (been a while since I experimented with it).

 

Not saying that's necessarily bad, but it's not what I was looking for. I like things to stop changing once their applied and dry. Part of that is because I want the tone to be stable.

Thank you. Can you say what type of resin you use in your varnish? or what type you would consider stable enough to meet that criteria?
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Thank you. Can you say what type of resin you use in your varnish? or what type you would consider stable enough to meet that criteria?

I'd rather not. I'm already having serious supply problems.

Treated (as in limed) rosin may be OK. It's just that I'd moved on before I had a chance to test it to my satisfaction (which could have taken several years). Exposure to intense UV, heat, observing wear pattens on knife handles varnished with it, etc.

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Resin, Rosin, what is it you really use, is there no difference between these two in English?

Colophony = Pine Rosin right?

Hello Peter, Yes I used colophony from the southern US. What's left after making turpentine. It starts out very pale and very transparent. Can you show a photo of what you cook that would turn black in 22 days? To me that's interesting. What is it called in Sweden? Is there a distributor who ships to the US? I would like to try it.

http://www.diamondgforestproducts.com/Products.html

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Hello Peter, Yes I used colophony from the southern US. What's left after making turpentine. It starts out very pale and very transparent. Can you show a photo of what you cook that would turn black in 22 days? To me that's interesting. What is it called in Sweden?

http://www.diamondgforestproducts.com/Products.html

 

Hi

 

This is the (domestic) stuff I use

 

(Pine) Rosin = (Tall) Harts

 

(http://en.wikipedia.org/wiki/Pine)

(http://sv.wikipedia.org/wiki/Tall)

 

It looks like this:

 

post-37356-0-29163900-1405520367_thumb.jpg

 

I realized that you have a saucepan lids on your cook, which I don't as i only cook it for a short time (150 C)

So that explain why you can cook it so long. But the color is not much darker after 22 days than my 1 hour cook.

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In a linseed oil/pine rosin varnish, I think the rosin acidity will need to be brought down somewhat to keep it from eventually altering and corrupting the oil component. I've had things go downhill as quickly as within a year.

 

I'm not a chemist, so that's just my theory on what happened. Rosin alone seems to be decently stable.

If I understand correctly the goal of liming rosin is to lower the acidity to make the varnish harder and raise it's melting point. Why does rosin seem stable alone? Is it because of the acids in the linseed oil that raise the level even higher. If the fatty acids are removed from from the raw oil through washing, would that not help to lower the acidity back down to just the rosin alone? So the goal is to use a washed oil that have the fatty acids removed.

If all the acids are removed from the oil and the rosin is limed to increase hardness will that not make the varnish too hard and brittle? Causing the failures that David mentioned? So leaving in some acid is a good thing, no lime. I guess finding a good balance is the key, but measuring these things is the hard part.

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This is a wild guess, but I think you on the other side of the Atlantic have more difficulties with Varnish cooking than we Europeans have. European pine colophony and linseed oil (especially Nordic cold pressed) might be superb for varnish cooking?

 

With the ingredints that I use I could very well put 50/50 Colophony/linseed oil, with no preparation in a sauce pan and heat it to 150 C for 30 min and have a pretty good varnish.

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Kremer gives an acid number range of 162 - 178 mg KOH/g for all common colophony resins derived from various pine species.  I don't have useful sense of this kind of measurement as it compares to pH. It doesn't sound like an extraordinary range.  Can someone more versed in such language give a layman's comparison? 
Is linseed oil acidity measured with pH, as it occurs in liquid state?  If so, it should be easier to measure the effect washing has.

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