Slumping Bottles Vertically

Today’s article was sparked by a question from a reader:

“Have you ever slumped a bottle vertically in the kiln, I want to achieve an artistic slump rather than a melted pile.  I figured if anyone had tried it it would be you.  Thanks, Andy”

Oddly enough, I hadn’t ever tried it, so I thought I would give it a go.

First I measured how deep my kiln is, this helps tell me how tall my bottles can be.

It looks like I have 9.5″ of kiln height.  I’m measuring from the shelf to the top rim of the kiln.  BUT, I have a very old kiln, and the elements do extend down into the kiln space.

So, I’d better subtract 1.5″ for element clearance, giving me a total height of 8″.  Now, how tall are my bottles:

I’ve selected two small bottles, one airline size Bombay Sapphire and one baby food jar, I’d like to see what a taller,  narrow bottle does, and a lower, wider bottle.  I also needed bottles that I had identical multiples of.  I’m firing these using my standard firing schedules so I know where to start, rather than just choosing a random temperature.

So, here we go, these two are fired using a full fuse schedule:

Next up is a Tack Fuse Firing Schedule (100 degrees lower than a full fuse):

And these two at a Slump Firing Schedule:

Here are the bottles next to each other so you can see the progress:

Things I learned:

  • Bottles aren’t an even thickness all the way around or top to bottom
  • The thin parts bulge out and slump first
  • Bottles don’t slump straight down (see previous)
  • Wider, shorter bottles are more predictable
  • The ideal slumping temperature seems to be somewhere between a slump and a tack fuse (about 1400)

Reader additions:

Hi Jodi – I tried this with a green beer bottle.  Thankfully, I was checking it because it went sideways and

hit the side coils.  I was able to remove it before any harm was done.  -Connie

If you try this and like your results, please let me know!

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