Varnish Sample...

[Michael_Molnar]

9 hours ago, Jim Bress said:

This is a cut off from the willow cello back that’s part of my current build. Over a year ago I shaped the piece of scrap wood into a door wedge because it was already almost in that shape. I had just finished making a batch of varnish from Roger’s recipe plus bits of information I learned at a few of Joe Thrift’s workshops. I thought a doorstop would be a good stress test for the varnish. A year + of kicking into a door bottom (you can just make out some scrape marks) and the varnish is nearly undamaged. There are places where the wood dented but the varnish didn’t crack, and it won’t take a scratch from a fingernail. I didn’t lime the rosin. Maybe it’s a fluke batch that happens to work. I guess I’ll find out in time. Point is, I don’t think you’ll get all your answers from the ingredients, as the main ingredient is the cook. 
 

Jim,

Please give helpful details such as oil:rosin, additives, pigments.

[joerobson]

16 hours ago, charliemaine said:

@Joe, as a veteran varnish maker, without stepping on others toes, what can you say about cooked rosinate varnishes? How do you see them holding up compared to yours? Need some honest insight. It has been mentioned that liming rosin in essence equals a rosinate varnish. Can you explain some  differences between your varnish and these other rosinate varnishes? 

I'm trying to decide what would be the best varnish to use on the last few fiddles I make. To me you are the best one to ask, having decades of experience.  And I'm sure you have made these rosinates yourself. 

Colophony is an acidic material with a relatively low softening and melting point.

Varnish made from this material will have the same softening point with predictable results.

A varnish made by reacting the colophony with calcium hydroxide is a rosinate varnish.

I choose lime because it is traditional and does not affect the color of the resin/oil mixture.   Adding lime drops the ph, raises the softening/melting point, makes a harder more polishable varnish which is more brittle.

We choose the % of lime to add based on these characteristics.

I have made the colored rosinate varnishes.

I abandoned that road based on the optics of the varnish....not that they are bad...just not what I was looking for.

I cannot speak to the long term durability of the rosinate colored varnishes.   My colophony based varnishes wear and protect in predictable ways.

on we go,

Joe

[Michael_Molnar]

I want to add a point about my own misconception. I forgot that Maberry’s process differs from Michelman’s. Could someone give me a link to the Scroll article? I’m too exhausted to look for my copy.

 

 

[David Burgess]

36 minutes ago, joerobson said:

Colophony is an acidic material with a relatively low softening and melting point.

Varnish made from this material will have the same softening point with predictable results.

I disagree.

 

36 minutes ago, joerobson said:

I choose lime because it is traditional and does not affect the color of the resin/oil mixture.   Adding lime drops the ph, raises the softening/melting point, makes a harder more polishable varnish which is more brittle.

I agree that it's best to lower the acidity of the rosin, because the oil/rosin combination can start to embrittle severely over time if it is too acidic.

[Michael_Molnar]

24 minutes ago, David Burgess said:

I disagree.

David,

Wouldn’t a fossilized resin be a case in point for Robson? 

[joerobson]

4 minutes ago, Michael_Molnar said:

David,

Wouldn’t a fossilized resin be a case in point for Robson? 

Fossilized resins like amber and copal, which I have made for decades do not wear in the manner common to violins.

[joerobson]

1 hour ago, David Burgess said:

I disagree.

Would you provide some information on this.  It goes against my study of the trade and my experience.   The only exception is not colophony.  Pure larch resin, unadulterated,  has a very low ph....almost neutral.

I agree that it's best to lower the acidity of the rosin, because the oil/rosin combination can start to embrittle severely over time if it is too acidic.

[JacksonMaberry]

2 hours ago, Michael_Molnar said:

I want to add a point about my own misconception. I forgot that Maberry’s process differs from Michelman’s. Could someone give me a link to the Scroll article? I’m too exhausted to look for my copy.

 

 

My process differs greatly in the making of the varnish. However in the making of the resins, the two JMs do things more or less the same way. 

[David Burgess]

4 hours ago, joerobson said:

Colophony is an acidic material with a relatively low softening and melting point.

Varnish made from this material will have the same softening point with predictable results.

 

4 hours ago, David Burgess said:

I disagree.

But I agree that it's best to lower the acidity of the rosin, because the oil/rosin combination can start to embrittle severely over time if it is too acidic.

 

3 hours ago, joerobson said:

Would you provide some information on this.  It goes against my study of the trade and my experience.

4 hours ago, David Burgess said:

Sure. The longer rosin is cooked, the higher its melting point becomes. If cooked long enough, its melting point will become so high that it cannot be dissolved in heated linseed oil, without heating the linseed oil to the point that it catches on fire.

Now if you want to use this information in your varnish teaching workshops, please assign proper credit.

Sorry, but I still think of you as pretty much a putzer and self-aggrandizer, compared to what some others in the fiddle trade can do with varnish.

And I do not appreciate your rendering some of my posts as if you had posted them, and some of your posts as if I had rendered them. Clean that lame sort of conniving sh*t up, Dude, or "heads will roll".

 

[JacksonMaberry]

6 minutes ago, David Burgess said:

 

 

 

Damn, I have not experienced getting colophony to the point that it becomes impossible to solve in hot oil. I have not cooked beyond about 200 hrs, and in those cases not hotter than 220C or so. Super curious about this though. How long would you say do you have to cook it to get it to act this way? Thanks!

[David Burgess]

10 minutes ago, JacksonMaberry said:

Damn, I have not experienced getting colophony to the point that it becomes impossible to solve in hot oil. I have not cooked beyond about 200 hrs, and in those cases not hotter than 220C or so. Super curious about this though. How long would you say do you have to cook it to get it to act this way? Thanks!

A lot depends on the amount of air flow. Cook colophony at 220C with little air flow for something like 12 hours, and it might get much darker and reduce to about half its original volume. Put a fan on it, keeping the colophony at the same temperature for the same amount of time, and you will get something resembling ashes, insoluble in heated linseed oil, or any solvent I have tried.

[JacksonMaberry]

2 minutes ago, David Burgess said:

A lot depends on the amount of air flow. Cook colophony at 220C with little air flow for something like 12 hours, and it might get much darker and reduce to about half its original volume. Put a fan on it, keeping the colophony at the same temperature for the same amount of time, and you will get something resembling ashes, insoluble in heated linseed oil.

That is wild, thanks man. This makes sense insofar as burning anything requires ample oxygen. Now imagine cooking rosin in a pure oxygen atmosphere ... On second thought, let's not. 

[joerobson]

38 minutes ago, David Burgess said:

 

 

 

 

David,

Certainly longer cooking under the right conditions lowers the ph.  I have not seen it do so to my satisfaction. 

If I over-road a comment by you it was certainly unintentional.

On the rest, you are entitled to your opinion.

Meanwhile.

on we go,

Joe

[David Burgess]

11 minutes ago, joerobson said:

David,

Certainly longer cooking under the right conditions lowers the ph.  I have not seen it do so to my satisfaction. 

Satisfaction from lowering the ph being what? I thought the whole point of adding a base was to at least partially neutralize the acidity.

And I don't appreciate your latest blank quote attributed to me. What's your strategy? "If you can't dazzle 'em with brilliance, baffle 'em with bullsh*t?"

[joerobson]

37 minutes ago, David Burgess said:

Satisfaction from lowering the ph being what? I thought the whole point of adding a base was to at least partially neutralize the acidity.

And I don't appreciate your latest blank quote attributed to me. What's your strategy? "If you can't dazzle 'em with brilliance, baffle 'em with bullsh*t?"

David

Satisfaction in terms of the hardness/softness and polishing and wear character of the varnish.

As far as the blank quote, I had nothing to do with that.

Joe

[Jeffrey Holmes]

Think the blank quote first appeared on Mayberry's post.. i have no idea to which post it is linked to

[sospiri]

On 5/11/2022 at 6:29 PM, JacksonMaberry said:

Bermuda Triangle. 

It makes people disappear.

[Jim Bress]

8 hours ago, Michael_Molnar said:

Jim,

Please give helpful details such as oil:rosin, additives, pigments.

Hi Mike, The varnish is approximately 1:1 colophony:linseed oil. The only other resin is mastic tears. That's it, no pigments or anything else. 

I say approximately because I don't think the ratio tells the whole story. Certainly mastic tears does not have the same properties as colophony. Likewise, cooked colophony (reduced in volume by 80-90%) does not have the same properties or even chemical structure of uncooked colophony. I have a citation someplace that talks about the compound structure created from linseed oil and colophony will vary depending on the temperature the compounds are formed. Likely the varnish of a given batch is comprised of multiple compounds, but that's speculation. I don't worry about the various compounds because it's something outside of my control. However it may partially explain the variance between varnish batches.

My uncolored varnish (not cooking the colophony down) is 50% colophony, 40% linseed oil, and 10% mastic tears by weight. I don't add the mastic tears until the varnish is stable between 95 and 100 C. Too cold the mixture won't incorporate into the varnish, too hot and the mastic tears will boil off.

For color, I melt the cooked colophony with equal weight linseed oil and add to the uncolored varnish (before adding the mastic tears) until I'm happy with the color (about 50% of the uncolored varnish volume). Adding the mastic tears increases the viscosity. I add additional linseed oil to get back to the thickness of room temperature honey (ish). So 1:1-ish.

I think I have a PDF of Jacksons Scroll article, or at least I have the issue. When I locate it I will send it to you.

Cheers,

Jim

[JacksonMaberry]

16 hours ago, Jeffrey Holmes said:

Think the blank quote first appeared on Maberry's post.. i have no idea to which post it is linked to.

The forum has been misbehaving a bit lately, both in terms of web page performance and some of our members unfortunately. 

Not to be too picky, but it's "Maberry". There's no RFD named for me.

[Jeffrey Holmes]

15 hours ago, JacksonMaberry said:

The forum has been misbehaving a bit lately, both in terms of web page performance and some of our members unfortunately. 

Not to be too picky, but it's "Maberry". There's no RFD named for me.

My mistake... I get Jeffery or Homes a lot myself.  :-) Typos corrected.

[Michael_Molnar]

18 hours ago, David Burgess said:

A lot depends on the amount of air flow. Cook colophony at 220C with little air flow for something like 12 hours, and it might get much darker and reduce to about half its original volume. Put a fan on it, keeping the colophony at the same temperature for the same amount of time, and you will get something resembling ashes, insoluble in heated linseed oil, or any solvent I have tried.

This needs clarification. I experimented bubbling pure oxygen through liquid colophony at 250 C. The result for me was a high yield of dark red colophony. No ashes. However, no else should try this. It is very dangerous because it can produce explosive and toxic peroxides  I no longer do this.

I have tried blowing a fan across a pot of cooking colophony. It promotes evaporation of the colophony decreasing the yield. Then, the small puddle will burn, which is what you may have seen.

So, the magic trick is to promote oxidation while limiting evaporation.

[Michael_Molnar]

Jim,

Nice varnish. Thanks.

[Don Noon]

11 minutes ago, Michael_Molnar said:

So, the magic trick is to promote oxidation while limiting evaporation.

And somehow limit the speed of oxidation to avoid explosions and fires.

[David Burgess]

8 hours ago, Michael_Molnar said:

This needs clarification. I experimented bubbling pure oxygen through liquid colophony at 250 C. The result for me was a high yield of dark red colophony. No ashes.

Had you done this long enough (rather than stopping at some mid-stage), I'm pretty sure you would have ended up with ashes.

There are basically two major things going on when cooking colophony (not that there couldn't be hundreds of other factors):

One is similar to a simple distillation process, in which the more volatile components are (selectively?) removed. And this can vary, depending on how much of the distillate is reduxed or recirculated back into the mix.

The other is oxidation, and I'm thinkin' that's where most of the darkening comes from, since pale yellow rosin,  at twice its color density, still looks pretty pale.

So at this point, I'm going along with what Jim Bress suggested earlier in this thread. We still do not know exactly what is going on with heating rosin, since it has never been provided the budget furnished to the nuclear war program.

What I do:

I try to keep careful records of my experiments, and when something works out well, that helps me in repeating it. A bugaboo is that I have only heavily experimented with varnishes for about 50 years, so there could be color endurance, and wear property differences between the varnish I use, and what was used by Stradivari.

[Don Noon]

2 hours ago, David Burgess said:

We still do not know exactly what is going on with heating rosin, since it has never been provided the budget furnished to the nuclear war program.

I haven't read it carefully (or really at all), but maybe there's something applicable in the paper Colour Responses to Heat-Treatment of Extractives and Sap from Pine and Spruce for those so motivated.