Polariscope - A new Tool

I've been doing, or attempting anyway, more sculptural items lately - and in particular - working off mandrel and trying to get my head around the way of working - in which you work from one end to the other, never going back into the flame and allowing the glass to cool to room temperture. (Annealing happens later.) This allows you to work much larger and not have to keep the entire piece warm - but I have to admit - it is something of a leap of faith after working with a "must keep the glass warm" mindset. Old habits die hard - and it is such a reflex to keep flashing the item into the flame, that to not do it requires conscious thought.

One of the tools I thought I would use to try to get my head around this a polariscope.

A polariscope allows you to see the strain in clear and light transparent glass. Perhaps this way I can get a better sense of where I am creating strain in the sculptures, and adjust the way I am making them, if necessary!

This is the polariscope - some assembly was required. The thing to remember is the blue dot on the base glass lines up with the blue dot on the top screen. The object to be viewed goes between the top glass screen and the backlit screen of the base. It included a light bulb - and I have to say - whatever else comes of this experiment - I am in love with the lightbulb! A halogen bulb in a heavy, heavy glass bulb. It pumps out a tonne of heat and it a lovely, bright light.

Oh, I miss real light bulbs - I'd soon raise bees and make my own beeswax candles than use compact fluorescent bulbs.

Testing the Polariscope

Firs - I wanted to check that it is all set up right and working correctly. I took some clear plastic, a baggie as a matter of fact, and viewed it under the polariscope. I know that it should look relatively even, like this. I have to admit - this plastic seems fairly stressed to me. But evenly stressed.

Then I took the baggie and tore and pulled and poked and stretched it. Now - it is quite a different picture - you can clearly see the stress in the rainbow patterns in the middle.

Next - let's check out some rods of clear - these have been used, and so the ends are somewhat stressed from heating.

Next - let's look at some actual stuff. This flameworked sculpture has been through an annealing cycle - so I would expect this one to look fairly good. And - in fact - she does. (That bright rectangle is the flash from the camera - nothing to do with the polariscope or the glass being viewed.)
This one, however, has not been annealed yet. It doesn't look too bad, but I can see a definite difference, especially from the upper torso to the lower, and the arms.

I don't really know how to interpret what I am seeing in greater detail yet. Guess I'm going to have to do more research. In the meantime - gotta love those rainbow colours!

I'll keep you posted as I learn more.