Fused Glass Artistry

Feeling the Heat – Temperature Dependence of Draping Vases

One of my first exposures to fusing glass involved a very simple class where we selected 1 sheet of glass, cleaned it, figured out the center, and placed it over a form in the kiln.  The instructor worked some kiln magic and after several hours invited us to peer into the kiln to see how the flat sheet of glass had begun to fall around the form.  (This is technically draping and not slumping glass).DSCN1437

How cool!  Was it really that easy to make beautiful glass vases?  I didn’t know enough to realize what factors played a role in creating the magical whimsical handkerchief forms.  Nevertheless, like a junkie’s first hit, I was hooked.

Yes, the instructor muttered under her breath about the danger of over-firing the glass and actually getting the mold stuck within the glass and having to destroy the glass and even the mold but who was listening?  This post will not auger into disaster scenarios, though.  (There is plenty of time for examples later…).

With time, I have begun to see the versatility possible with creating vases.  Obviously one can fuse many pieces together to create a 2D sheet that is far more complex and exciting than a single color sheet of glass like I was first exposed to.  Another Boulder artist, Bobbi Vischi (www.bobbivischi.com), takes this to an awesome level.

The key to the final shape all comes down to temperature.   I have conducted a experiment creating vases that have been taken to different slump temperatures.  Remember, glass most soften and begin to melt.  The amount the glass ‘melts’ is temperature dependent.  The glass will first seem to fold along one axis creating what is affectionately known as a ‘taco’ (or is it because this always seems to occur at lunch time during classes?).  As the temperature is increased, the glass moves more and additional folds are created.  At higher temps, the glass really begins to take on the form of mold it is draping over.  Go much further and you are risking it all.

‘Don’t forget time!’ you may say but that seems almost secondary to the ultimate heat the glass is exposed to.  At low temperatures, even if I hold for an extended period of time, I can’t seem to move much beyond the taco shape.

Pictures tell the story the best.  In all cases, the kiln firing schedule was as follows:

Ramp     150F/hr     to 300F          and Hold for 15 minutes

Ramp     300F/hr     to 1100F        and Hold for 20 minutes

Ramp     150F/hr     to SLUMP TEMP     and Hold for X minutes

Cool       400F/hr     to 950F          and Hold for 1 hour

Cool         150F/hr     to 800          and Hold for 10 minutes

Example 1:  1175F for 1 min (Hit Taco shape at 1100F)DSCN1426Example 2:  1200F for 1 min

DSCN1461

               Example 3:  1225F for 1 min (about as far as want to go)

DSCN1382

Now back to experimenting with my vases….

Advertisements

One response

  1. Pingback: Less is More – Downsizing a Vase | Geek Girl Glass

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s