Glue/sawdust filler

[Dean Sibley]

As an anitique restorer I have been aware for many years of this for repair. But tests done early in my career showed a week result which fell apart quite easily - as such I never used this technique until recently. The pix show one of a set of Georgian dining chairs I had to restore - about 200 yrs old & still in daily use! After many reupholsterings the many nails & staples used to hold the fabric had literally destroyed much of the (hidden) wood. Large holes were naturally chiselled out & mahogany blocks glued in. However I thought I might revisit the idea of glue/dust filler for smaller holes with surprising result.This time I was using titebond.

Oh bother(insert worse ) I have just been interrupted again 2nd time in 2 days, by Goodgame Empire gaming pop-up. I hit the "x" to close it & later found it on my "desktop" screen - can anything be done about this?

Sorry about that rude interruption.

This time when making the glue mix I used shavings from under my sawbench rather than dust - as from router. The longer, fibrous particles seemed to absorb the glue giving a very hard & strong mix. Note I would only use this if unseen in finished work. Also the ratio of glue/shavings is important - not too much glue.

Also a restorer's rule is what ever is used on an antique or project that might become antique should itself be restorable - applies to materials, glues, finishes etc.

 I find it surprising that ca & epoxy glues appear to be commonplace in luthery. The above rule is also why I dislike modern lacquer finishes.

3rd pik shows where a previous repairer had simply stapled cardboard over damaged corners.

[Ned Knepp]

Dean, there are quite a few of us, around here, that use different glue depending upon the value and age of the instrument involved. The general consensus seems to be that instrument built with hot hide glue should usually be repaired with the same. When it comes to other repairs like cracks or missing bits of wood that are probably needing permanent fixes, it may be that a newer type of glue is a better choice.   

I use CA or cracks on newer instrument because it works pretty well and it pretty quick. Larger/longer cracks might require titebond or HHG. On old instruments I use HHG for everything unless there is no other option. 

It all comes down to using what is appropriate for the instrument. 

Reversibility is one of the things we have discussed a lot in the past. I think that this is an idea that may be heavily applied on some instruments and  and pretty much ignored on others. If an instrument is collectable, potentially collectable, High value or otherwise "desirable" for some reason, a lot of us will try to make sure that any modifications are as reversible as possible.  On inexpensive, not so desirable instruments making them playable is probably a higher priority.

 

[Andrew]

Wood boat restorers often use epoxy (West Systems is popular for good reasons) to strengthen wood that has suffered dry rot and wood bores. Generally epoxy would be the best glue to mix with sawdust/shavings as a filler because its 'cohesive' strength is much superior to any of the other glues common to guitar repair. There are also fillers available designed specifically for this purpose, and other purposes like fairing etc..

[onewent]

Hi Dean ... I'm curious at to what changed from earlier in your career to now, regarding use of dust and glue?  Different glue, technique?

I know the old Windsors were not glued, but rather the joint/wedge held things in place.  Are the formal colonial/federal era chairs like yours glued?  Never thought about it.

BTW, some of my guitars look like that chair frame ;-)  Tom

[Dean Sibley]

Hi Tom,

the join on these chairs was  mortice & tenon with HHG. As you might guess the 2 motices required - at right angles to each other at the top of the leg - would have removed a lot of wood - leaving very little on the inner corner. About Victorian times these changed to dowel joins which were a little better because less wood was removed. The dowels seen in pix would have been done by previous restorer. Also early smooth sided dowels tended to push the glue out of the hole to either end. Now fluted dowels hold glue much better. replacing all old dowels with fluted is the only way you will get a good long lasting join.

 The difference in the filler is 3 fold - early glue used was Aquadhere. Probably local(Aus) brand. It was quite watery, white glue. Titebond is thicker & yellow.  The major difference in technique I think is not using wood dust ( as from router) but longer more fibrous particles from under sawbench after using a ripping blade. These are 3-5mm long & give structure to the filler like chopped strand mat does to fibreglass. Also the wood/glue mix on early trials was a fairly "wet" mix whereas recently the mix was drier & getting sticky even before application as the wood fibres soaked up the glue. Basically dust floating in a sea of glue as compared to fibres in close contact all glued to each other. Does that make sense? The recent version set like a rock with good adhesion.

Hope this helps,

Dean

[onewent]

Thanks Dean, that's interesting.  Never thought of making different type dust with a saw.  I just use sand paper to make dust for guitar repair purposes.  Might have to experiment with the 'saw' dust dust.  Tom