u-wave oven: I just MELTED a frickkn BEER BOTTLE

Reasoning goes like this:

1. Glass is normally an insulator

2. Hot glass is an electrolyte (sodium or boron ions)

3. Manufacturers keep their glass molten by passing kiloamps through it.

4. If glass had the right resistance value, it might strongly absorb microwaves.

5. I've heard stories where pyrex cups were melted by a microwave oven.


>From long experience with microwave ovens we know that glass is
not a very good absorber.  However, what if the glass was 
pre-heated to incandescent temperature?  Would its electrical
resistance be a match for a microwave oven's characteristics?
Easy enough to find out.

I found my cheap propane torch and grabbed a handy bottle.
I donned eye protection then carefully flame-heated the whole 
side of the bottle to prevent cracking from thermal stresses, 
then I heated a small spot in the center until it glowed dimly 
red.  The hotspot was about the size of a dime.  Propane 
torches aren't great for glassblowing, but they can heat glass
until it just starts to soften.

I placed the bottle upright in an empty 1000-watt microwave oven, 
used the torch to keep the hotspot glowing until the last instant, 
then slammed the door and hit "start."

The hotspot rotated out of sight as the bottle rode around
on the turntable.   When it came back into view, it wasn't
dimly glowing red.  The hotspot was bright orange and about 3cm 
in diameter!  It's like a forest fire: the small hotspot heats
the neigboring glass, which then becomes conductive and absorbs
radiation, heating the next bit of glass, etc.  The hotspot
grows as if the material were on fire!   The glowing glass slumped 
as I watched.  I stopped the oven quickly in case this was 
overheating the magnetron.  (maybe it's not!  maybe I just need 
a slab of firebrick to place beneath the bottle.)

Hmmmmm.   INterrrrrresting, no?

What shall we try melting next?

Ooops!   Good thing I left the oven door closed.  After about 
two minutes the bottle went "tink!" and flew into hot shards as 
it cooled and contracted.

(((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))
William J. Beaty                            SCIENCE HOBBYIST website
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