Mike Molnar's Bench

[Michael_Molnar]

13 hours ago, Rue said:

I think we performed that experiment in Organic Chemistry 202...

Seriously - hope it goes well and that you to present!

 I tell my wife that this is my science contest entry.

[Michael_Molnar]

1 hour ago, scordatura said:

Looking forward to your discoveries. So glad you are willing to share with our community!

The big issue is that we all went down this path thinking that we solved the mystery and only to realize later that there is egg on our face. I'm on a low cholesterol diet, so I tread carefully. BTW, look at the  VSA competition entries and realize that some are better than the Cremonese instruments. 

[MikeC]

as long as the egg is on the face and not on the fiddle it's good.  

[Michael_Molnar]

I'm now making and testing varnish colors. I think I have learned a lot in the last couple of months. I'll be explaining what I have done.

Here is a photo of my color testing collection. The slides have sample that can be compared to my ground.

The issue is that my ground is a light Hansa yellow with chestnut-colored figure. The varnish medium is cooked rosin that is somewhat black cherry red. If I add the customary Cremonese pigments such as madder or cochineal, it comes out orange which I do not like. Yes, I know that orange is the standard color, but I want something redder. So, I have been testing lots of pigments to understand absorptive colors and how they mix. 

 

 

[Michael_Molnar]

7 minutes ago, Michael_Molnar said:

I'm now making and testing varnish colors. I think I have learned a lot in the last couple of months. I'll be explaining what I have done.

Here is a photo of my color testing collection. The slides have sample that can be compared to my ground.

The issue is that my ground is a light Hansa yellow with chestnut-colored figure. The varnish medium is cooked rosin that is somewhat black cherry red. If I add the customary Cremonese pigments such as madder or cochineal, it comes out orange which I do not like. Yes, I know that orange is the standard color, but I want something redder. So, I have been testing lots of pigments to understand absorptive colors and how they mix. 

And here is a shot of one slide. The notation says that PR206 is the dominant varnish color and some PB29 was added for color compliment. 

 

 

[Michael_Molnar]

I used natural ingredients for my first three layers, but found that the 4th layer needed more control. Natural pigments are difficult to control. Madder as you know produces a cornucopia of reds, browns, and oranges. In the photo of the slide, PR206 (quinacridone maroon) is ascribed to brown madder. So, I gathered an extensive collection of pigments with known color characteristics for my testing. 

Stay tumed.

[scordatura]

Looks like you are doing a proper job Mike. I am looking forward to your findings. Have you looked at your vanish under UV light (wood lamp)? If so do they show the salmon color of the color varnish and the pale yellow of the ground?

[Don Noon]

Great idea to use microscope slides and storage box for varnish samples.  My large sheet of glass (marked off in rectangles) is a bit in the way and vulnerable, as well as running out of space... so I'll follow your sample example.

[Michael_Molnar]

9 hours ago, scordatura said:

Looks like you are doing a proper job Mike. I am looking forward to your findings. Have you looked at your vanish under UV light (wood lamp)? If so do they show the salmon color of the color varnish and the pale yellow of the ground?

I hope I'm doing the right things.  I still make mistakes. It bothers me something terribly when I repeat them. 

Yes, I use a UV inspection lamp. In some of the earlier photos you should find a fluorescent inspection lamp with a huge magnifying lens. I replaced the circular white light lamp with a UV one. I will report again about fluorescent colors, but for now I can say that my ground is a dark yellow with hardly any fluorescence. The clear varnish is bright white. And the colored varnish depends on the pigments, but I have to look more closely at the cooked rosin varnish. I find that the natural anthraquinone family produces that salmon glow. This will include madder and cochineal. There are other things too that could do this, but I would have to verify that. So, I need to do some more due diligence here.

Edit: The salmon color is likely due to the cooked rosin. See below. 

Edited July 16, 2019 by Michael_Molnar
Correction

[Michael_Molnar]

1 hour ago, Don Noon said:

Great idea to use microscope slides and storage box for varnish samples.  My large sheet of glass (marked off in rectangles) is a bit in the way and vulnerable, as well as running out of space... so I'll follow your sample example.

I also use the cover slides to develop varying coat thickness from undertone up to the saturated masstone as the artists call these. The problem is getting them to dry without dripping all over the storage box. Notice how I set the box upright to eliminate that. Sometimes I put the slides under UV to dry them out completely. Get the slides with white label strips. 

[Michael_Molnar]

Here is how I evaluate the color hue and chroma of cooked rosin. I fill a 4 oz. medicine bottle with acetone and dissolve 10 g of rosin or varnish in it. Here, is a lineup of some rosins.

My initial take on the cooked rosin is that it is greatly misunderstood and has taken on mythical claims. It is undoubtedly an oxidation process. Depending on the rosin source, a red color develops with heat. B&G reported that they noticed a significant red color in Strad's varnish. I claim that this is due to cooked rosin, one possibility that they suggested. In fact, I find it a challenge to prevent this color development in making clear colorless varnish. I keep my rosin cooking to below 230 C. 

I know that Roger Hargrave and his colleagues use cooked rosin varnish without any pigments. They can do this because their ground is a dark brown made from equum stercore urina. If you do not have a dark ground but a light yellow or tan, the result can be a bland orange. Then, like Strad, you need to add pigments, not much, but some to darken and redden the instrument. Or, start with a dark ground. Pick your poison.

I am using cooked rosin with pigments because my ground color is a yellow ochre. I need to pull the color to something close to burgundy. I find that fat varnishes seem to lose or dilute the red color. I also add lime to making varnish but not to cooking the rosin. The lime reduces the linseed oil acidity and gives the varnish better properties. My varnish is close to 4:1 to 3.5:1.

Stay tuned.

[Michael Szyper]

3 hours ago, Michael_Molnar said:

This will include madder and cochineal

The only fluorescent anthraquinone which may fit the historical use is purpurin, I don’t think that the natural made alizarin has any fluorescence. Cochineal does the opposite, it is partly uv absorbing. I am not shure if the pinkish fluorescence is maybe an effect of the white glowing clear coat making the pigments shine in the natural color. I.e. a pseudofluorescence.

[Michael_Molnar]

2 hours ago, Michael Szyper said:

The only fluorescent anthraquinone which may fit the historical use is purpurin, I don’t think that the natural made alizarin has any fluorescence. Cochineal does the opposite, it is partly uv absorbing. I am not sure if the pinkish fluorescence is maybe an effect of the white glowing clear coat making the pigments shine in the natural color. I.e. a pseudofluorescence.

I need to see what B&G and others say about this. Thanks.

-----

OK. I was confused for sure. In B&G pp. 39-40, they make a case that the salmon fluorescence is due to the cooking method of the colored varnish making up Layer 4. This color is seen in Layer 4 regardless of the pigments. Thanks for alerting me.

I will re-examine the fluorescences I see in my varnish system. I suspect that it is due to the roasting process. Stay tuned.

Edited July 16, 2019 by Michael_Molnar
Re-read B&G

[Evan Smith]

Thanks for all the work Mike,,

I'll be getting some microscope slides and a proper box to store them,

what a great Idea!

An easy way to keep track of the colors used on each fiddle.

[Michael_Molnar]

Here's an example using cover slides to make a wedge for studying dichromatic varnish. BTW, this sample is not mulled very well so it is not very transparent nor is it dichromatic.  But I happen to have this photo on hand.

[Michael_Molnar]

Here is how I put the black edge on the scroll. I use a toothpick as a brush. The black ink is water-based, so it cleans up easily from a varnished surface when I make a mistake. I put this on after the clear coat varnish has dried. I use a 240 grit sanding stick to cut a sharp chamfer through the varnish down to the wood. When I am pleased with the final result I apply the first coat of colored varnish which seals the black ink. 

IIRC, and am not having a senior moment, this is what Strad did but he used lamp black in varnish. I bet he used toothpicks from fine Italian restaurants. 

[Three13]

Fine work!

[Michael_Molnar]

l see that there is a thread currently discussing grounds. I believe that the "stain" is not UV tanning but a regularly practiced treatment to enhance wood figure. I use the concoction in this jar. It is wood ash.

Wood ash solution is an old standard way to stain wood. It is loaded with high pH ingredients that stain wood. In fact, this is from where the term “potash” originates. Wood ash can explain the chemical analyses that researches detect. If it is applied in a slurry, you get the "rubble" found by some researchers. Depending on the trees and the temperature of the fire, the concentration of calcium, silicon, phosphorous, etc., will vary.  A slurry of wood ash water can also contain particles of quartz and calcium carbonate. If it is properly filtered, there are no particulates (rubble). In my photo, the particulates (calcium carbonate, the largest component of wood ash) have settled to the bottom. Because the chemical composition varies, I synthesized a "likely" wood ash.

[MANFIO]

Nice! Do you boil your wood ash in water?

[MikeC]

When mixing ash with water it's been my experience that the ash is dark gray and the water (potash lye) has sort of an apple juice color.   So I'm puzzled why the sediment looks so white and the water so clear and colorless.  

[Ken_N]

I'm guessing that Michael uses.... gasp... chemicals.  The horror of it all! 

I've done great looking grounds and still managed to mess the varnish job up!  Don't know if chemicals would help.  Maybe being retired now I can be less spur of the moment, and more disciplined in my varnishing.  

I did find that my tap water makes left over hide glue turn to water in a few days.  Yes, the creek behind my house flows into the Flint river.  So I'm learning something.  Yes I did buy a bottle of distilled water for glue, but I still drink it from the tap for tea. It doesn't work well in the Keurig; we use bottled spring water for that.

Michael, the finish on the scroll is quite nice.

[Michael_Molnar]

I used chemicals because it is easier. No boiling was needed. In fact, the old method was to let rainwater steep through ashes in a barrel that had straw and sand lining the bottom. A hole in the bottom let the brew pass out. I'm sure production quality varied. 

[Michael Szyper]

Michael, very interesting! Is this all you use for coloring wood? I thought you used some kind of water soluble colorants?

[Michael_Molnar]

8 hours ago, Michael Szyper said:

Michael, very interesting! Is this all you use for coloring wood? I thought you used some kind of water soluble colorants?

Right. Let me review that.

My next step is to apply a water soluble colorant that infuses ("impregnates" à la B&G) the wood. If the colorant lies on the surface, the wood will appear burnt destroying 3D effects of the flames (chatoyancy). Nevertheless, some colorant collects in pores and microscopic structures which we call "pore filler". The colorant used by Stradivari et al. according to B&G was aqueous - water based. I claim that it was most likely slightly fugitive. What we see today has faded. Some old instruments have less fading than others.  The fading involves light and slow chemical reactions.

Look at the STRAD poster and other good photos of the Stradivari Viotti. I recall that the lower treble back has some burnt appearance, not much, but it's there. This tells me that Stradivari went a little beyond the infusion limit. The strength of a water soluble colorant can be easily reduced with some absorbent tissue to wick up any excess. If I see any burning, I blot up that area with damp tissue paper.

I have been evaluating one colorant for some time and will gladly share those findings if I find a way of securing acknowledgment (memorialize) of my hard work.

One other feature of my system is that it needs (requires) protein such as collagen, albumin, or casein. The protein's role is two-fold. It seals the wood from subsequent varnish penetration and stabilizes the colorant.  Proteins were a favorite medium even though protein was an unknown concept at the time. That fact tells me that organic (protein) chemistry is involved.

Stay tuned.

[Jim Bress]

Mike, For credit where credit is due, I suggest publishing your findings in a format that can be cited.  I know you're no stranger to publications so this is doable for you.

-Jim