A New “Oh Shit!” Moment

11 Dec

I thought I had saved my commission pieces yesterday, and to a large extent I did.

I reached the stage where all the sanding was complete and I started to do one last round of burnishing to bring out a mirror shine before buffing.

And then the green chrome diopside stone popped out of one piece!

The Big Squeeze was at it again.

The most important part of a faceted gemstone when embedding and firing in place is to place the pavilion (girdle and culet) the correct depth in the clay without covering too much of the crown and without the culet extending beyond the bottom of the piece:

faceted stone

This is fairly straightforward when embedding stones without an open back. Trouble, like doming and too little of the girdle getting caught in the sintered silver, are more pronounced when the setting is open in the back.

For the five other stones, I assume the girdle was further down and were securely embedded in the silver:

Right

The stone that popped must not have been down as low and so was barely below the level of the silver:

Wrong

When I flattened the dome caused by the shrinkage of the open back settings (note in “after” firing diagrams, silver has been drawn inward at the bottom), both the top of the setting was compressed further and the back of each setting was spread.  Unfortunately, since the girdle of the stone that popped was barely embedded, reversing The Big Squeeze caused the “unstoppable force” to meet a “movable object,” forcing the stone’s girdle so close to the surface that it was released.

Once the movable object was removed, the unstoppable force relaxed its tension and spread into the top opening, making it smaller.  There was no way that stone was going back into the setting.

Out came the needle files and several hours later, I could finally seat the stone’s girdle in the enlarged setting.  Now how was I going to keep it there?

There is only one way to sinter unfired metal clay to a piece already fired, and that is to add lavender oil to your metal clay paste.  In order for this fix to work, there has to be enough room to surround the stone below, at and above its girdle.  I tried three times and could not get the stone down low enough into the setting while leaving room between the side of the setting and the girdle area, at least not without turning the setting into a closed back.  If I could enlarge the setting more, I could build a ring inside the setting for the stone to become trapped in, but because of the width of the piece and the anti-glare shield, that isn’t an option.

When setting smooth cabochon stones, adhesive is sometimes used.  The two preferred adhesives are two-part epoxy (which does not always dry clear) and E6000 (which does always dry clear).

Solution

I used E6000 to reset the stone and it looks excellent thus far.  However, E6000 has to cure before the “patch” can be tested.  My solution to this problem is not elegant, and I wouldn’t recommend it under any other circumstances.

The only other “fix” is to build a new piece from scratch.

In 24 hours I will know if this solution worked.ohshitsign

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