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Sanding betweeen spirit varnish coats

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Hi
I was reading in later posts how to sand between "spirit" varnish coats , not oil varnish but I did not find what I need.
I want to sand some to level some spots. I am in the middle of the varnishing process.
So the question is:
¿How may I sand spirit varnish, what to use: water, oil, sand paper, rotten stone, caolin..?

Thanks for any advice.
Regards
Tango

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I don't often sand between coats of spirit.  But when I do I use polysand and a little mineral oil -- water if you want more abrasion.  Depending on your varnish formula it may not take much abrasion to level the areas you are talking about.  and the varnish that remains after the alcohol has evaporated is so thin, it takes virtually no pressure beyond the weight of the materials.

https://kdproducts.com/product/foam-backed-sheets/

 

The reason I like this is that the foam backing is soft so the material conforms to the contour of your surface whereas other products I find to be too stiff.

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Even I almost never sand between coats, at most once before starting with colored varnish,  only if there are small protrusions like dots of dust to be smoothed. The foam supported paper indicated by Julian is fine, I use a similar one of the micromesh or normal micromesh without foam support. I use water only for sanding, or sometimes dry but become clogged very quickly.

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The primary reason some makers choose to sand between coats is to get rid of debris and brush hair that gets into the varnish. If you keep your brush very clean and control the dust in the air where you varnish, you can usually eliminate the need for sanding.

If you decide to sand, you could use a fine grit paper (1500 or so) with oil or water. As Julian said above, water doesn’t cut the abrasiveness as much as oil. You could also use a powdered abrasive like pumice or rotten stone with oil. Then there are the different pads and cloth-backed abrasives, like Micromesh and Scotchbrite.

Be careful, though—sanding can easily remove texture or too much varnish. Also, if you use oil with your abrasive, make sure it’s all cleaned off before applying varnish to avoid adhesion issues. 

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"Sand" it by rubbing it with a piece of soft yet fibrous wool or felt, and do not rub fast in order to keep the heat down. Then go wash your hands and then wipe it with your bare hand to act as a tack rag. If you find a hair, spec or nib, pick it off with a fingernail, if it leaves a "shoreline" or ring, those areas can be rubbed more aggressively in order to generate a little heat which will help blend the area. In general avoid abrasives, if you must, buy micromesh pad kits that come with stepped grits.

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35 minutes ago, jezzupe said:

"Sand" it by rubbing it with a piece of soft yet fibrous wool or felt, and do not rub fast in order to keep the heat down. Then go wash your hands and then wipe it with your bare hand to act as a tack rag. If you find a hair, spec or nib, pick it off with a fingernail, if it leaves a "shoreline" or ring, those areas can be rubbed more aggressively in order to generate a little heat which will help blend the area. In general avoid abrasives, if you must, buy micromesh pad kits that come with stepped grits.

Happily, the polysand also comes in stepped grits.

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Hi 

This is the case:

I stripped a violin, then varnished with a 1704 with sandarac and mastic added.
This 1704 was made with a coloured alcohol (pernambuco). The hue obtained is a yellow- very light brown. I guessed the pernambuco would cover more.
The next coat must be with some dye to achieve a darker brown. Not very dark .
There are some little spots and places that deserve a sanding. I don´t want the coloured varnish stay arround that spots making stain little points.
That´s all
Thanks for advices
Tango

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14 hours ago, David Burgess said:

Sanding of varnish should be avoided as much as possible. A good violin finish is not modeled after the finish on a bowling alley. ;)

As much as I can agree with this (at least to a certain degree) you should also convince many musicians who ask for and like smooth and brilliant varnishes, like many ancient ones overpolished to the death who have somehow created a standard and are probably the majority:rolleyes:

How do we get out from this?

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You do not need to sand, as this will remove varnish. Just use a clean section of a brown paper shopping bag. This will smooth any high spots and burnish the finish a little bit. You must make sure the varnish is properly prepared (no dust or moisture).

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2 hours ago, Davide Sora said:

As much as I can agree with this (at least to a certain degree) you should also convince many musicians who ask for and like smooth and brilliant varnishes, like many ancient ones overpolished to the death who have somehow created a standard and are probably the majority:rolleyes:

How do we get out from this?

We are not just makers, we are educators!  :ph34r::lol:

Print some pictures of the varnish texture on some unusually well-preserved old fiddles, the more valuable the better. The Messiah Strad might be a good choice for you and I, since we don't antique. Then we can say stuff like, "What's up with the excessive wear and overpolishing BS on some of those old clap-trap fiddles? This is the most valuable fiddle in the world, and it has texture and looks almost new". ;)

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Even the Messiah Strad hasn't escaped the polisher's ra - although the polishing looks minor. So many wonderful pictures are available from public websites of major collections. This is one of my favourites - just Beautiful!

1644 A Guarneri Viola Tenor (LLib) -ARCHING -top -dimensional -bass -cBout.jpg

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I use a .005 scraper to remove nibs, brush hairs, dust, snot, breadcrumbs or anything else that ends up in the varnish.

It won't remove the texture if i'm sober.

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12 hours ago, Evan Smith said:

Urban Luthier,,,

What is this a picture of, it is magnificent!

Hello Evan, it is a photo of the Andrea Guarneri tenor viola in the Shrine to Music ND. I agree it is wonderful

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On ‎5‎/‎10‎/‎2019 at 5:02 PM, David Burgess said:

Sanding of varnish should be avoided as much as possible. A good violin finish is not modeled after the finish on a bowling alley. ;)

Unless one is finishing a viola.....

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On ‎5‎/‎11‎/‎2019 at 12:29 PM, Davide Sora said:

As much as I can agree with this (at least to a certain degree) you should also convince many musicians who ask for and like smooth and brilliant varnishes, like many ancient ones overpolished to the death who have somehow created a standard and are probably the majority:rolleyes:

How do we get out from this?

 

On ‎5‎/‎11‎/‎2019 at 3:36 PM, David Burgess said:

We are not just makers, we are educators!  :ph34r::lol:

Print some pictures of the varnish texture on some unusually well-preserved old fiddles, the more valuable the better. The Messiah Strad might be a good choice for you and I, since we don't antique. Then we can say stuff like, "What's up with the excessive wear and overpolishing BS on some of those old clap-trap fiddles? This is the most valuable fiddle in the world, and it has texture and looks almost new". ;)

Lady-Blunt-Stradivarius-Violin-of-1721-1

Lady-Blunt-Stradivarius-Violin-of-1721-1

 

 

 

 

Lady-Blunt-Stradivarius-Violin-of-1721-9

Lady-Blunt-Stradivarius-Violin-of-1721-2

 

Lady-Blunt-Stradivarius-Violin-of-1721-8

 

 

Lady-Blunt-Stradivarius-Violin-of-1721-1

 

Lady-Blunt-Stradivarius-Violin-of-1721-1

 

 

Lady-Blunt-Stradivarius-Violin-of-1721-1

Lady-Blunt-Stradivarius-Violin-of-1721-1

 

 

Lady-Blunt-Stradivarius-Violin-of-1721-1

Lady-Blunt-Stradivarius-Violin-of-1721-1

 

 

Lady-Blunt-Stradivarius-Violin-of-1721-1

 

Lady-Blunt-Stradivarius-Violin-of-1721-1

 

Lady-Blunt-Stradivarius-Violin-of-1721-5

 

 

 

 

 

 

 

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I like subtle textures like Lady Blunt (are these the photos from M. Darnton?), nothing to do with some very rough textures that look like plowed fields:)

Look at the reflection of the bridge, a similar sharpness implies a fairly smooth surface.

Lady-Blunt-Stradivarius-Violin-of-1721-2.jpg.e40b9fa65fa0c34221de6b76adad0d15.jpg

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Apparently even the Lady Blunt hasn't escaped the polishers rag. Apart from the Guarneri above, does anyone know of any truly unpolished historical examples? the Medici instruments perhaps? 

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22 hours ago, Davide Sora said:

I like subtle textures like Lady Blunt (are these the photos from M. Darnton?), nothing to do with some very rough textures that look like plowed fields:)

Look at the reflection of the bridge, a similar sharpness implies a fairly smooth surface.

Lady-Blunt-Stradivarius-Violin-of-1721-2.jpg.e40b9fa65fa0c34221de6b76adad0d15.jpg

I wonder how much it has changed in 310 years, even though it has not been played much?

 

17 hours ago, Urban Luthier said:

Apparently even the Lady Blunt hasn't escaped the polishers rag. Apart from the Guarneri above, does anyone know of any truly unpolished historical examples? the Medici instruments perhaps? 

Yes, it has been repolished around the bridge, but maybe not in other areas?

I assume this one hasn't been french polished or oil polished?

https://s215.photobucket.com/user/PeterRatcliff/slideshow/Strad?albumview=slideshow

 

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1 hour ago, sospiri said:

I wonder how much it has changed in 310 years, even though it has not been played much?

Yes, it has been repolished around the bridge, but maybe not in other areas?

The grain becomes very narrow toward the center, lending itself to decreased texture. I try to avoid wood with extremely narrow grain for exactly that reason.

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16 minutes ago, David Burgess said:

The grain becomes very narrow toward the center, lending itself to decreased texture. I try to avoid wood with extremely narrow grain for exactly that reason.

May I enquire why you feel that way about decreased texture?

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