crack filling

[Guido]

I've just redone an old crack on a top, running the length of the body. It was half open (for a long time) and half glued badly out of register.

I have opened it, cleaned it, and managed to glue it in register now. However, some wood fibres near the outside (varnish side) are missing, leaving a bit of a gap in places.

How would you go about 'filling' this?

[The Violin Beautiful]

I think it would probably depend on the amount of fiber missing, but if it’s a very small amount, you could use a couple different things to fill in the void. You might try Deft to level, then varnish over the top to even out the color and sheen. Some people have moved away from Deft and are using a mixture of aluminum hydroxide and shellac instead.

If more material is missing you might consider replacing the fibers with grafts from the inside of the top. 

[Jeffrey Holmes]

You may want to do a Google or Maestronet search on the subject of filling cracks.

As TVB mentioned, what to use depends on the size and depth of the voids.  

If the voids are appropriate for varnish fill: I'm one of those who moved away from Deft long ago, but Deft is very easy to level and many restorers happily continue to get along with it. I don't use straight shellac either (the Hills used a variety of orange shellac in the mid 20th century as fill, and it is a devil to remove if the crack needs to be re-worked). I prefer the fill to be a bit harder than deft; so not to swell when adding the retouch, stable, and relatively easy to remove if the occasion arises; so I use a clear varnish I make just for the purpose of fill, applied on the thick side (so it doesn't penetrate the wood deeply). I've mentioned the ingredients in several old posts but I'll repeat it: Sandarac, Manila Copal, and shellac in alcohol.  If you want to try it, play with the ratios a bit until you find something you're comfortable with. You can dissolve the resins in different containers, let them settle and clear, then pipe out the stuff on the top to play with the ratio. Adding aluminum hydroxide can offer a little more body when required and makes leveling with a scraper much easier. It also helps "matte" the fill a bit so you aren't fighting the gloss so much when you retouch. 

Larger voids may need (again, as TVB mentioned), wood, or you can try glass microspheres... but if you use glass, make sure they are below the surface with fill varnish or deft at the surface. Microspheres do not scrape well (at all?) and it's a little tricky to get the reflection "right" if the fill is deep (it may require making a paste with the spheres, a bit of fill varnish and a tiny bit of color).

Hope this helps.

[duane88]

Jeffrey,

 

Do folks still use Soluvar? That suggestion came from the visit to the Conservation Lab of the Smithsonian years ago.

[Jeffrey Holmes]

Yes.

 I do know several restorers who use, or have used, it.  I never got comfortable with it myself, but I know one or two people (who post on the board) have mentioned to me that they've had good luck with  it.  Maybe they'll chime in.

[Guido]

Any experience with Zweihorn/ Durofix crack filler? Is it very similar to Deft?

[Jeffrey Holmes]

3 minutes ago, Guido said:

Any experience with Zweihorn/ Durofix crack filler? Is it very similar to Deft?

Can't say that I have.  I've not seen it in the US. If it's similar to Deft, though, I'd probably not choose to use it myself. 

[Andreas Preuss]

Would be instructive to see a photo demonstrating the problem. 

 

 

[sospiri]

9 hours ago, Jeffrey Holmes said:

You may want to do a Google or Maestronet search on the subject of filling cracks.

As TVB mentioned, what to use depends on the size and depth of the voids.  

If the voids are appropriate for varnish fill: I'm one of those who moved away from Deft long ago, but Deft is very easy to level and many restorers happily continue to get along with it. I don't use straight shellac either (the Hills used a variety of orange shellac in the mid 20th century as fill, and it is a devil to remove if the crack needs to be re-worked). I prefer the fill to be a bit harder than deft; so not to swell when adding the retouch, stable, and relatively easy to remove if the occasion arises; so I use a clear varnish I make just for the purpose of fill, applied on the thick side (so it doesn't penetrate the wood deeply). I've mentioned the ingredients in several old posts but I'll repeat it: Sandarac, Manila Copal, and shellac in alcohol.  If you want to try it, play with the ratios a bit until you find something you're comfortable with. You can dissolve the resins in different containers, let them settle and clear, then pipe out the stuff on the top to play with the ratio. Adding aluminum hydroxide can offer a little more body when required and makes leveling with a scraper much easier. It also helps "matte" the fill a bit so you aren't fighting the gloss so much when you retouch. 

Larger voids may need (again, as TVB mentioned), wood, or you can try glass microspheres... but if you use glass, make sure they are below the surface with fill varnish or deft at the surface. Microspheres do not scrape well (at all?) and it's a little tricky to get the reflection "right" if the fill is deep (it may require making a paste with the spheres, a bit of fill varnish and a tiny bit of color).

Hope this helps.

Jeffrey, could we please have a way of accessing old threads on important topics such as crack repairs? Maybe a list of useful old threads as a locked thread that is at the top of the pegbox list? Some other websites do this to avoid endless searches for that old thread that you just can't find?

[Jeffrey Holmes]

4 hours ago, sospiri said:

Jeffrey, could we please have a way of accessing old threads on important topics such as crack repairs? Maybe a list of useful old threads as a locked thread that is at the top of the pegbox list? Some other websites do this to avoid endless searches for that old thread that you just can't find?

Honestly, Sospiri, unless I have a bunch of volunteer help appear from the mist, that task would fall to me...  and I'm afraid I cannot devote the time required at this point.  Since this board spans 2 decades, decisions ob what to include, and what not to, would be daunting.  There are many, many subjects that repeat themselves here.

The MN reach function has options that make searches much more fruitful...  One just has to play with them a bit and figure them out.  I just did a search on "crack repair" in which I selected search wide parameters from the options.  Even your post came up on it along with six pages of others.  Narrowing the parameters will yield more selective results.  Google is so deep that conjuring up Maestronet and just about any subject in a search will bring results galore.

[Salve Håkedal]

15 hours ago, Jeffrey Holmes said:

...  Sandarac, Manila Copal, and Shellac in alcohol.  If you want to try it, play with the ratios a bit until you find something you're comfortable with ...

Shellac is tough and Sandarac is kind of brittle, I think(?) But I'm not familiar with Manila Copal. Will it add softness/ductility to the mix? Or something else?

[scordatura]

Pre thickened Deft is not too bad of an option. It was taught in the course by Hans Nebel.

[tango]

Hi Jeffrey
 

Is Al(OH)3 the "aluminun hydroxide" formula
I want to try that and need to translate to spanish correctly to order to the chemist store,
Thanks
Tango

EDIT: Hidróxido de aluminio is the name translated by Wikypedia

[Jeffrey Holmes]

16 hours ago, Salve Håkedal said:

Shellac is tough and Sandarac is kind of brittle, I think(?) But I'm not familiar with Manila Copal. Will it add softness/ductility to the mix? Or something else?

Manila Copal is hard and very clear (and dissolves in alcohol but leaves some solids at the bottom of the container).  Sandarac has body.  Shellac properties vary a bit depending on the wax content. Unmodified, the fill I use holds well, but can be chipped out with a knife point relatively easily.  With the AH, it's a bit more pliable but not nearly as soft as Deft.

Edit: One colleague I know will also add mastic...I don't, but they like the way it handles.  If you're trying this stuff, test it for drying time (much faster that Deft) and hardness (how it scrapes; you'll need a very sharp scraper with little or no burr) and modify the mix as needed.

[Jeffrey Holmes]

3 hours ago, tango said:

Hi Jeffrey
 

Is Al(OH)3 the "aluminun hydroxide" formula
I want to try that and need to translate to spanish correctly to order to the chemist store,
Thanks
Tango

EDIT: Hidróxido de aluminio is the name translated by Wikypedia

Yes.  Kremmer carries it if you have access to their products.

[tango]

Thanks Jeffrey.

I will try here in Buenos Aires first. Our post service and customs are a disaster 

Regards

[Jeffrey Holmes]

9 hours ago, tango said:

Thanks Jeffrey.

I will try here in Buenos Aires first. Our post service and customs are a disaster 

Regards

To aid your search in Buenos Aires, this is Kremers listing: http://shop.kremerpigments.com/en/fillers-und-building-materials/structural-und-special-fillers/5593/aluminum-hydroxide-fine

[chungviolins]

Is aluminum hydroxide soluble in alcohol?

[Jeffrey Holmes]

4 minutes ago, chungviolins said:

Is aluminum hydroxide soluble in alcohol?

Stays in suspension...

[chungviolins]

Ok, thanks 

[Stephen Faulk]

Is there any use for Aluminum Stearate or has anyone evaluated it a filler in crack fill varnishes ? 

[pbelin]

You can make aluminium hydroxide by reacting alum and caustic soda or potash. 

[sospiri]

On ‎18‎/‎04‎/‎2018 at 6:30 PM, Jeffrey Holmes said:

Honestly, Sospiri, unless I have a bunch of volunteer help appear from the mist, that task would fall to me...  and I'm afraid I cannot devote the time required at this point.  Since this board spans 2 decades, decisions ob what to include, and what not to, would be daunting.  There are many, many subjects that repeat themselves here.

The MN reach function has options that make searches much more fruitful...  One just has to play with them a bit and figure them out.  I just did a search on "crack repair" in which I selected search wide parameters from the options.  Even your post came up on it along with six pages of others.  Narrowing the parameters will yield more selective results.  Google is so deep that conjuring up Maestronet and just about any subject in a search will bring results galore.

I undersatand Jeffrey. My own attempts to search old threads even with advanced search input wastes too much time so tha't what got me thinking of an alternative method. Every day it gets harder to search for stuff on the internet. Results galore is the problem; needle in a haystack scenarios.

[Jack Devereux]

Jeffery, what led you to stop using Deft, if you don’t mind my asking? 

[Jeffrey Holmes]

14 hours ago, Jack Devereux said:

Jeffery, what led you to stop using Deft, if you don’t mind my asking? 

Though easy to handle, among other things, I felt it continued to shrink for a very long time, was a bit too soft (found that retouch does better in the long run over something harder that itself) and sometimes clouded under certain retouch.  As I mentioned, I know a number of fine restorers who still get on with it very well.