Monday, May 14, 2012

Learning to Work Your Glass (Part I)

     This is a reminder:  the glassblowing portion of my blog, is a refresher for my students who has had my glassblowing class or someone who has glassblown before.  If you have not glassblown, I suggest you take a few beginner lessons. 

Supply List:
Torch set up
Burt's Bees burn cream/q-tip
Size 3 tip for you torch 
Heavy screen  
Wet/dry sandpaper
Ceramic mat
8 mm tubing
File/glass cutter

Breaking the glass:
     Using a file or glass cutter, place a small score scratch across the glass.  Remember, the scratch doesn't have to be that long.
     If you are using a file, scratch the glass by bring you file forward or away from you.  Do Not, bring the file back towards you, this will flatten the tines on the file and ruin it.
     Dampen you finger with water, or spit, and wet your score mark.  This may seem strange to those of you who has not done this, but it all has to do with the Chemistry of the glass.  The water/"Mom's magic spit", speeds up the rate of the glass cracking (breaking the silica bonds).  If you don't do this step, your glass won't break properly.  Don't laugh, try breaking glass without spit. 
     Use a towel, for safety, to cover the glass as you break it.  It is very important, when breaking glass to pull out and bend the glass back at the same time.  The pulling out part releases the stress on the back end so the glass breaks cleanly.

45 degree angles:
     Break off about a 6" piece of 8 mm tubing.   Using a heavy piece of screen, whack the end of the glass, at an angle, using quick/hard blows.  Use smaller, lighter strokes to make finer fractures.  This method is similar to flint knapping arrowheads.  Once a rough angle is made, add a little water to the wet/dry sandpaper and smooth the ends and edges (ground glassing the end).

Lighting the torch:
    Use the "POOP" method (propane on, oxygen on, oxygen off, propane off).  
     Have your flame ready and hold it near the torch tip.  Turn on the red knob (propane), and obtain about a 6" orange flame.  Turn on the green knob (oxygen), and obtain about a 3/4" blue flame.
     Turning off the oxygen first (green), then the propane (red).  DO NOT OVER-TIGHTEN THE KNOBS!!!!!  YOU'LL RUIN THE NEEDLE VALVES AND YOUR TORCH WON'T PROPERLY TURN OFF!!!!!!!!!

Bends ("U" and 90 degree):
     Remember:  Hot glass looks the same as cold glass!!  Don't burn the top of your bench, put your hot glass on the ceramic mats.  Using about a 12" piece of 8 mm tubing, heat your glass at the point were you want the bend.  Remember to rotate your glass, to heat it evenly.  Once the glass heats up, it will start to bend.  Slowly bend your glass to the desired angle.  Bending it too quickly will cause the glass to crimp/buckle.  Once you have mastered this turn off the torch.  Remember:  Turn off the green knob (oxygen) then turn off the red knob (propane).  DO NOT OVER-TIGHTEN THE KNOBS!!!!!

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