Goran74

Sealer for Marciana's recipe?

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Since now I use mostly making spirit varnish. This time I would like to try for the first time the Marciana's varnish (2 parts oil, one part colophony, one part mastic). I make some experiments on some wood pieces. I used first tea and let in the light for some days since I do not have UV box. What sealer should I use before the varnish? I read some topics here but the subject is unclear. For the spirit varnish, I use uncolored shellac. But what now?

Also, if I do not use the " ground burnt alum" as the original recipe describes, does it change something dramatically in the varnish?

Thank you

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Clear, dewaxed shellac should work fine, alternatively colourless varnish, with pumice or plaster of Paris added. I would recommend reading Roger Hargrave’s bass making article. I used colophony dissolved in turpentine as a sealer and it brought the wood out nicely. You can add any particulate matter really, so long as it doesn’t affect drying, and has the same refractive  index as the varnish. Mastic was not found in Stradivari’s varnish, just colophony and oil. Alum will help the colour though. 

Good luck, post your results on mn, as I would be interested in seeing them. 

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Hello Goran74,

I too started my oil varnish experiments with the classic Marciana recipe.

At the time, all (reliable) information available to me was Gary Baese's book, that I borrowed from the school library in Cremona.

I changed my recipe over the years, but I stayed on a 1:1 resin:oil ratio every time I made a varnish containing linseed oil, mastic and colophony. One change I tried was: 1 part mastic, 2 parts colophony, 3 parts oil.

1- since a deeply colored varnish is desirable, I would use much less mastic and more colophony compared to the original Marciana's.

2- mastic is expensive!

So, if I had to choose another recipe, I would take R. Hargrave's version of the classic varnish that he published in his great double bass tutorial. But, the Marciana recipe can work well and I think that Luis Manfio is the expert on this.

I have almost always used Strasbourg turpentine to make a deeply colored colophony. Once I used Aleppo pine resin that I collected here in Sicily and it worked fine too. I made another varnish with spruce resin scraped from trees around my hometown, Aosta and I got a light brown-tinted varnish.

I remember reading a Strad article by Gregg Alf where he advised using a high resin ratio varnish for his sealer/ground layer, mixed with red tripoli to make a smooth paste that he used to fill the pores before laying the varnish coats.

So, maybe you will want to make a second varnish batch with higher resin:oil ratio and use it as a filler in the way that Gregg Alf recommended.

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On 4/8/2019 at 1:41 PM, Goran74 said:

Since now I use mostly making spirit varnish. This time I would like to try for the first time the Marciana's varnish (2 parts oil, one part colophony, one part mastic). I make some experiments on some wood pieces. I used first tea and let in the light for some days since I do not have UV box. What sealer should I use before the varnish? I read some topics here but the subject is unclear. For the spirit varnish, I use uncolored shellac. But what now?

Also, if I do not use the " ground burnt alum" as the original recipe describes, does it change something dramatically in the varnish?

Thank you

Marciana varnish applied properly doesn’t need a sealer.  Wipe a couple thin layers before regular application makes a great ground.  If it’s made well it can increase stiffness slightly, and even decrease damping  

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23 hours ago, Anthony Panke said:

Roger Hargrave’s bass making article

Thank you very much for the proposal. I have already read Hargrave's articles on his site. Very informational for varnish too. 

22 hours ago, Giovanni Corazzol said:

So, maybe you will want to make a second varnish batch with higher resin:oil ratio and use it as a filler in the way that Gregg Alf recommended.

Thank you for your opinion. I have not read Gregg's article but this procedure sounds good. Maybe I will test this kind of sealer. 

8 minutes ago, Advocatus Diaboli said:

Marciana varnish applied properly doesn’t need a sealer.  Wipe a couple thin layers before regular application makes a great ground.  If it’s made well it can increase stiffness slightly, and even decrease damping  

Thank you Advocatus. I will try it straight and without sealer to some test blocks I have. 

Do you know if color added or can be added to Marciana's receipt? And If colour can be added what would be the best? Powder (which I used effectively earlier) or artist's colors? 

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Some makers of artist oil colours like the Old Holland brand have been recommended on this forum because they contain less oil compared to other brands.

I have tried the "Italian brown pink lake" which is basically an iron oxide pigment, so it's not very transparent and must be used sparingly.

You can also find some different kinds of "colour extracts" made specifically for instrument varnish, these ones can be easier to mix into your varnish.

 

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On 4/10/2019 at 10:13 PM, Giovanni Corazzol said:

Some makers of artist oil colours like the Old Holland brand have been recommended on this forum because they contain less oil compared to other brands.

I have tried the "Italian brown pink lake" which is basically an iron oxide pigment, so it's not very transparent and must be used sparingly.

You can also find some different kinds of "colour extracts" made specifically for instrument varnish, these ones can be easier to mix into your varnish.

 

Thank you so much for your answers and your time. Is there any problem if I use NaNo2 before applying the varnish? I like a lot your suggestion 3:2:1 ratio. My experiments with chemicals have not good results. Basically I see colours like green or pink that I cannot recommend for quality instrument. 

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On 4/8/2019 at 11:44 PM, Anthony Panke said:

Clear, dewaxed shellac should work fine, alternatively colourless varnish, with pumice or plaster of Paris added. I would recommend reading Roger Hargrave’s bass making article. I used colophony dissolved in turpentine as a sealer and it brought the wood out nicely. You can add any particulate matter really, so long as it doesn’t affect drying, and has the same refractive  index as the varnish. Mastic was not found in Stradivari’s varnish, just colophony and oil. Alum will help the colour though. 

Good luck, post your results on mn, as I would be interested in seeing them. 

Hello again. I made the receipt. Cooked about an hour. The right is not diluted and the left is diluted with turpentine. I like a lot the result. The not diluted dried in less than 48 hours. With turpetine dries a lot faster. I am not still sure if the diluted works well as sealer and does not let pet spots, if wood absorb more than it should. Also I want to test the color that Mr Giovanni proposed. I bought it and I am planning to mix it with diluted varnish.

IMG_20190415_220848_155.JPG

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Looks good. 

Quite pale though, perhaps try sometime cooking the colophony beforehand- low temp, long time until it is really black. 

Put enough clear coats on until a thin layer builds up on the surface. 

Good luck

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