Cold Varnishes

[ViolinLove20]

Hello all,

As a city person with very limited resources, cooking smelly/toxic varnishes is out of the question for now. So, I was hoping we could begin a thread talking about oil or spirit varnish recipes that don't require heating/cooking. So far I only know of the Darnton Mastic Varnish recipe.

Also, if you have worked with the varnishes mentioned, feel free to write your opinions and experiences.

Thanks!

[Michael.N.]

I don't think that Spirit varnishes need cooking. I've certainly made them by cold solving them. Just leave the resins/alcohol in a jar for a week or so. In fact I'm unsure what the cooking actually achieves in the 1704 recipe, apart from speeding up the whole process. Anyone know?

 

I did one batch of the Darnton mastic varnish and it worked very well. Very easy to make. Some people seemed to have trouble with it (not drying?) for reasons beyond my understanding.  It's very clear, so you will have to obtain your colour by other means.

Cooking resins can produce a lot of nasty fumes.

[ViolinLove20]

Ah, okay. I had thought that most spirit varnishes didn't involve cooking. Also, I'm glad to hear that the DMV worked for you. I'm going to attempt it soon and will document my trials with it.

[Ken_N]

Emulsions are not cooked, but are a different animal.  They dry more like spirit, but have oil in them.  Spirit is missing the oil component .  John Masters used to write about them a lot.  I made one up last summer that worked pretty well, but I didn't have it sealed good, and it dried up to a nice brown resin in the jar.  Seems like it is best to mix up only a little at a time, and use it fresh.

Ken

[ViolinLove20]

Ken,

Emulsions, I'll try looking them up. Thanks!

[go_oa]

The Michelman rosinate varnish requires melting the rosin,

but that happens at low temperatures (< boiling water).

The rest of the process is at low temperatures.

My first attempt, using old rental return Belmore rosin

and Draino plumbing lye, worked out well.

[ViolinLove20]

Go,

I could probably handle that. What's the process?

[Carl Stross]

 

I did one batch of the Darnton mastic varnish and it worked very well. Very easy to make. Some people seemed to have trouble with it (not drying?) for reasons beyond my understanding. 

 

It needs the right kind of linseed oil.

[Craig Tucker]

 Also, I'm glad to hear that the DMV worked for you. I'm going to attempt it soon and will document my trials with it.

 

Please do.

My own attempts with the DMV were also very productive, though I have to admit that the results were slow in getting the exact results that I wanted to get. .. the various linseed oils, and turps, the different brands and products available and then getting and using a pure asphalt (or road "tar") as a colorant - and then getting it all to WORK did take some time and experimentation.

Please show what you do, and what results you get.

This is going to be a real pleasure to watch somebody else do.

Thanks,

ct

[go_oa]

1) Melt some rosin out of the wooden forms. Remove the wood.

2) pour some drain cleaner over the rosin.

3) Heat is gently till it is liquid.

4) Add some water, alum and CaCO3.

    I got Alum from the the local Chinese grocery.

    I got CaCO3 from lo sodium baking powder.

5) Heat the mixture gently.  The mixture turns white.

6) Filter out the white stuff.

    I let it set a while, pour off the clear fluid,

    Used coffee filers to get the white stuff( Rosinate)

7) Disolve the rosinate in Turps.

8) test the result.    

[ViolinLove20]

Ct,

I'm glad to post my process! I hope that if someone else is curious about trying something, and I've tried it, that my experiences could help them along.

Go,

Thank you very much. Though, what purpose does the drain cleaner serve?

[ctanzio]

Many forms of rosin contain fractions that are not readily soluble in solvents and oils. One of the functions of cooking and chemical treatments of rosin in particular and resins in general is to remove or alter these factions so it can dissolve thoroughly and clearly in the solvent/oil. For cold mixing, you want to limit yourself to resins that readily dissolve in a solvent and an oil.

 

Dammar and mastic gums are two types of natural resins that tend to dissolve thoroughly "cold" in solvent and oil. So if you want to experiment with traditional ingredients, you might research recipes using those to start. They are the principal ingredients in high end varnishes for fine art and antique wood structures and can create crystal clear coats that increase the color saturation of the surface it covers.

 

Drain cleaner is very nasty stuff and highly reactive. I would not mess with it unless you thoroughly understand how corrosive it can be. It will literally dissolve your clothes and your skin.

 

You can also use oil-based polyurethane as a synthetic resin instead of the rosin, dammar or mastic. It is a cheap, easy way to experiment with making varnishes and it will yield excellent results with cold mixing.

 

Here is the deal with solvents (like turpentine and mineral spirits), and oils (like linseed oil).

 

The solvent and oil will mix clearly but only up to a certain ratio. Then the ingredients no longer mix cleanly but instead form a cloudy suspension. Sometimes you can use very high ratios of solvent to oil depending on the quality of the ingredients. Other times the mix may cloud with ratios as low as 1 to 1.

 

If you are using  mineral spirits as the solvent because of its very low odor (try Type II) you have an additional challenge because it is milky white out of the can instead of clear. So you might not be sure if the cloudy appearance is due to that or lack of solubility in the oil. High quality mineral spirits and linseed oil should mix easily to ratios of 3 spirits to 1 oil. It will evaporate/dry to a clear finish.

 

A general approach is to start by dissolving the resin in a solvent. 2 grams per 100ml of solvent is a starting point. For polyurethane resin, try 3 solvent to 2 poly by volume.

 

You can experiment from here and see how it affects application and finish. Dissolving solid resins can take some time for cold mixing, like days. Filter to remove any particulates. The advantage of oil-based polyurethane is it mixes readily with solvent and is immediately ready for use without filtering.

 

Measure out an amount of oil you want to use, then add the resin/solvent to the oil slowly until you get the desired ratio, consistency and/or color. If the mix begins to cloud, you reached the solubility of the solvent in that oil. Ratios of 3 resin/solvent to 1 oil will give a thin wiping varnish that will easily dry. You might want to go to higher ratios depending on how much resin is dissolved in the solvent.

 

The softness or the hardness of the finish will depend on how much resin you got to dissolve into the solvent. More resin in the solvent gives a harder finish.

 

Ratios of resin to solvent to oil vary dramatically among recipes. So do not be surprised to find a general lack of agreement on proportions.

 

You will find a lot of recipes that say "add some of this" or "pour in a little of that". Like my grandmother who has been making pasta dough for over 70 years, she can tell by the look and feel when the proportions are right. So old wood refinishers may not need or even know exactly what proportions they use in their varnish.

 

But if one makes an effort to understand the chemistry of what is happening, then quantitative recipes can be created. I suggest you stick to those to start.

 

Finally, thick coats with lots of linseed oil will take forever to dry without some UV lamp curing. Very thin coats maybe 1 to 3 days depending on temperature and humidity, although it will transition from tacky to dry to the touch in maybe 8 hours, but will be too soft to handle.

[ViolinLove20]

Ct,

That is great information for me, thank you! I now have ideas to keep me busy for a while...

[FiddleDoug]

"The Michelman rosinate varnish requires melting the rosin,

but that happens at low temperatures (< boiling water).

The rest of the process is at low temperatures.

My first attempt, using old rental return Belmore rosin

and Draino plumbing lye, worked out well."

 

While I don't have any personal experience with them, I have heard that some of the Michelman rosinate varnishes turn really bad after a couple of decades.

 

VL20, Why don't you just buy your varnishes? There are quite a few sources out there for reliable varnishes that you don't have to cook. You just buy and use. Our own Joe Robson, at Violin Varnish Ltd. makes great products. Old Wood makes great products. All of the major parts and material suppliers (International Violin, Howard Core, etc.) sell products. You can get Behlens spirit varnish through the woodworking suppliers (Rockler, Woodcraft, Grizzly), and you can still get Ace Hardware Oil based Spar Varnish (Works well, by personal experience, and others here have used it as well.)

 

There's no real need to mess with trying to make your own varnish, with the associated hazards, that my, or may not give you a good product. Those varnish makers out there on the forum can probably give accounts of screwed up batches, and other mishaps.