posted 12-14-2005 06:00 PM            

I was moving this silver pitcher and when I picked it up I noticed this teensy weensy hole at the back of the handle where it attaches. Mind you, I have handled this piece a lot and never noticed this tiny hole. I assume it is a vent hole from when it was made?

My question is:
If the handle was made in two pieces why would you need a vent hole? Or if it was one piece would you even need a vent hole at all for that? I do not know the particulars of forming liquid silver into hollow handles, but it seems to me that basically you just let it cool in a mold? It isn't like clay or porcelain where it is super heated to set it and needs some release for the steam.

What gives and what is this tiny pin prick hole for?

posted 12-14-2005 06:36 PM            

The vent hole is needed because the handle is hollow. If it didn't have a hole somewhere, when it was sealed shut (either in putting the two parts together or in attaching it to the body, depending on the design) a partial vacuum would be created inside the handle as it cooled, potentially leading to its collapse. The hole allows the pressures inside and outside to equalize so that doesn't happen.

The same thing is done when firing ceramics with hollow parts, as you note, but it's not to release steam but expanding air trapped in the hollows. And if the glaze runs and blocks the hole, the piece can explode in the kiln.

When I was a kid we used to demonstrate the process using a metal gas can (unused, of course, to prevent explosion!). You'd heat the can with the lid unscrewed, then screw the lid on, and watch as it cooled. They'd crumple up like a ball of paper. Sometimes you could even straighten them back out (more or less) by reheating.