A friend has (had) a very nice Chinese carving made of turquoise. It
had a serious accident and is now in 3 or 4 pieces. I am wondering
what the best glue might be to attempt a repair. He asked me to do it
but I didn’t want to end up with glue running down it’s side or an
obvious seam. Any thoughts would be appreciated. Thanks.
Hi, In repairing the turquoise sculpture it seems to me that you have
two possible approaches. One you might call the restoration approach,
the other, simply a repair.
If the piece is valuable and significant (which is a judgment call,
perhaps to be made by an expert), it would probably call for a
restoration, that is, a repair that is reversible, that can be undone
later, and moreover be undone as far as possible without leaving any
visible traces on the piece. With turquoise, I’m not sure how I would
go about achieving this, since the stone is usually quite permeable,
and any ahesive, particularly a low-viscosity, “watery” one would be
likely to be absorbed into it, with two effects: it would leave a
line of discoloration along the fractures, and two, would be
virtually impossible to remove later.
On the other hand virtuallly ALL turquoise today is impregnated in
some way (with a plastic resin, sometimes even just with wax) to
enhance the color and make it less permeable. The hot needle test may
be helpful here - put a hot needle against an inconspicuous part of
the sculpture and see if it sends up a little tuft of smoke that
smells like burning plastic or wax. If it is already impregnated, as
it is likely to be, diffusion of an adhesive should be both less
pronounced (since the pores will already be sealed with the
impregnating substance) and less of a restoration issue.
If it is to be simply a repair, where you’re going for maximum
strength and permanence, without concern for the restoration issues,
I’d use a strong, slow-curing, two-part epoxy such as Araldite mixed
into a paste with turquoise dust (grind some matching turquoise to
fine dust in a mortar). This should yield a joint which in the worst
case is reasonably inconspicuous and if you’re lucky, is nearly
invisible.
Any excess adhesive after curing can be sanded away with
progressively finer silicon carbide paper glued to a popsicle stick
or similar. Finish with say 1,200 or 1,500 grit and then polish.
A final caveat is that if the turquoise is paraffin impregnated this
could impede the expoxy bond.
Hope that helps…
Cheers,
Hans Durstling
Moncton,
Canada
A friend has (had) a very nice Chinese carving made of turquoise. It had a serious accident and is now in 3 or 4 pieces. I am wondering what the best glue might be to attempt a repair.
You could use one of the super glues, but I find I get the best
results with this type of material (turqoise is porous) using
epoxies. I’d recommend the Hughs “epoxy 330” Also get a small can
of attack, a solvent for cured epoxies. the epoxy gives you decent
working time of about 15-20 minutes or so, with a couple hours to set
properly, but if you put the glued joint under an incandescent light
bulb to get warmed up a bit, it can be fully cured in ten minutes.
As with all epoxies, measure the two parts carefully. If you’ve got
a small scale (like a gemstone scale), weigh the two parts rather
than relying on visual estimates. Mix the two parts very well. Now
fit the repair parts together. if needed, do this in several stages,
fitting only two parts together at a time, and mixing new epoxy for
each new joint. You can use tape (scotch tape, or others) to hold
parts, or better, clamp them under a bit of pressure, using wood
clothes pins, rubber bands, or whatever you can come up with. After
fitting a joint, let a trace of glue extrude to the surface, but you
can wipe off excess you can easily reach. After the joint has cured,
though, use the Attack solvent on a rag to clean off any remaining
excess. The degree to which you’ll be able to get an invisible or
nearly invisible joint will depend largely on how much edges of the
pieces were damaged. Often when things like this break, the raw
edges have lost bits and pieces too, so the joint shows little gaps.
so then the seam shows up more. It will, if you look closely likely
still show unless theres so much mottleing and matrix in the stone
that it can hide in that pattern. It’s also possible to mix pigment
with the epoxy so it matches the color of the stone, but this often
doesn’t make the joint all that much less visible. Hope that helps.
Peter Rowe