The results...... Ok so what happened, how did this casting run go?????

Here is a picture taken just after the kiln was opened.



As you can see there is quite a bit of crap that fell onto the glass, most of it is oxides from the heating element, which formed well after the glass was too cool to be affected, but it is still a worry, the elements shouldn't have oxidised like that!

Here is a close up of one of the blanks.



You can really see the oxides and other dust that has fallen onto the surface, next time I will cover the molds with a sheet of ceramic fibre paper to keep this stuff out of the picture, I have some on hand and I really should have done it this time too, but I got ahead of myself, as you do when you're really keyed up and want to see a project come to fruition....

Here is a picture of the blanks carved free of the investment material, and roughly cleaned up.



As you can see Crystabolite investment material has contaminated the surface layer of the glass, this is not a real problem as you will see from the strain test results. However if you look real close, you can see some bubbles, these are a problem, I think these are a result of not holding at the casting temp long enough, in this case the hold time ended up being only 1hr 30mins, where it was intended to be 2hrs. I now realise it should have been closer to 4hrs, well live and learn, it's a new kiln and you have to work out how the beast likes to work!

Here are the test results for the three blanks.



Blank one.



Blank two.



Blank three.

As you can see there isn't any real darkening of the glass as they are viewed through crossed polarisers, it there was any strain present you would see dark areas or in extreme cases a rainbow of colours, try looking at a car window through Polaroid sunglasses, you will get what I mean!

So other than a few too many bubbles, and the metal oxide surface contamination, which should grind out anyway, I'm quite happy with the results of this casting run.

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