Science! Stress testing for fun and profit

[Kalorlo]

I finally got round to trying out Red Hot Sal's tips for a makeshift polariscope to check the stress in transparent beads. It's really cool! And also useful 

Things you need: some 3D specs left over from a 3D film (the modern ones, not the red-green ones). An LCD screen (laptop, flatscreen monitor, tv, etc).



1. Orient the glasses in front of the screen so they go dark (easier if you take the legs off). They won't be totally black, but there's an obvious dark way round. Legs will be pointing away from you if they're still attached.



2. Try putting a CD case between the glasses and the screen. Look, colours!



3. If you put the filter against your camera lens (or eye...) you can see the whole thing.



4. My bead. This is a broken in half lentil, unannealed. Pic here without filter.



5. Through the filter. It has black lines!



6+7. These two show that the lines shift as you rotate the bead.

With an annealed bead you don't see much of anything out of the ordinary. It's also a lot easier to see with something like a lentil rather than a small spacer. Need to find an unannealed spacer to see if I see anything there.

With this, you can check if your kiln is annealing your beads properly.