I have been using epoxy where you mix equal parts resin and hardener
and it sets up clear and colorless in 4 minutes (so the packaging
says). This week I had a customer purchase a pair of stud pearl
earrings cemented to their 14ky gold backs with this epoxy and she
said when she was taking them out the next day the pearl separated
from the post and back. Then yesterday I was setting up the displays
and an aquamarine heart drilled top down came apart from the 14ky
post I had cemented in with the same epoxy.
The weather has changed from winter to spring, both pieces have been
in the cases for a couple of months that much they have in common. I
don’t want to have this happen again. Any help would be appreciated
- what are you gluing together gems/pearls and metal with?
The post for the drilled items needs to be large enough to hold the
item on without glue and the glue is the insurance. I use 6000, found
at Michaels or other craft stores.
Veronica
Anne-Marie,
First, gluing gemstones (as opposed to pearls) is a risky business
anytime and I hate it but sometimes it has to be done. You usually
cannot use a forced fit on the post due to the possibility of
breaking the stone. You’re left with using a quality glue (referred
to in front of customers as “industrial bonding compound”) and
applying a minor amount of pressure during the curing process.
Throw out your current epoxy and buy the 1 hr cure Devcon two part
material. Be very sure your mix of equal parts is accurate and mixed
well - and be very careful not to contaminate the supply tubes with
the opposite part. Once you’ve applied the glue try to apply a little
pressure with, say, a soldering cross lock tweezer. I cover the ends
with a little piece of masking tape which both protects the stone and
gives the tweezer tips some traction on the stone. You may have to
adjust the pressure by bending the arms out a bit.
Once you’ve appled glue and pressure place beneath a 100w
incandescent bulb and leave for a couple of hours at least. Then
allow the piece to finish curing overnight without disturbing.
Pearls are different to the degree that you can force fit the post -
within reason - and it works even better if you use a square post
that you’ve twisted completely around a couple of times resulting in
a “corkscrew” post. When correctly done you can actually screw on the
pearl -coupled with the epoxy such a mounting should never come off.
Unfortunately pearls oftentimes come overdrilled re the post at hand
or underdrilled. In cases of underdrilling I re-drill the pearl. This
requires care as it is easy to chip the nacre. I use a a very small
pointed stone mounted on a mandrel and expand the opening of the
hole to accomodate the drill I intend to use. On lesser pearls I’ll
hold the pearl in a clamping jig and drill “freehand”. For more
valuable pearls I’ll use a pearl jig and my mill to make a more
precise hole. Never try to hold the pearl with your fingers while
drilling and, if you’re using pearl drills, never try to drill by
hand at all.
In the case of the pearl’s hole being too large I’ll change the post
if possible or I’ll use parallel jaw pliers to squeeze the top half
of the post causing it to widen out in a paddle shape which, while
not as effective as the twisted post, still gives some bite to the
mounting.
Apply and cure the glue as noted above.
Les Brown
L.F.Brown Goldwork
sounds like the maker "improved " the formulation…first, call the
company and ask them to replace your product…if you want to give
it another shot, and if they tell you they didn’t change the
formulation…
I have had success, but limited use of, gs hypo cement…it is tricky
because atmospheric pressure dispenses it for you out of the needle
like applicator so have a rag handy to catch the overflow once
opened…its available almost everywhere jewelry and beading supplies
are sold…
but I’d make sure, and I’m betting you have- that you roughen up the
posts with sandpaper fully,that will remove any traces of oils,
compounds, residue from pickle, or other non-desirable 's from the
posts,.Some stones are oiled; aquamarines and garnets in addition to
more widely known emeralds, turquoises and variscites and if the
stone is laser treated to remove inclusions little worm-like trails
are left inthe stones, that = hiding places for everything from oils
to soap, to lubricants used in cutting them,…so rinse your gemstones
under warm running water and mild soap and make sure there’s nothing
on the inside diameter of the hole to prevent a good bond…the pearls
are a bit more intriguing- that’s what made me think " new and
improved"…might be at the root of the evil…