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Q&A Monday – 10/24/16

Today I’m answering reader questions that were received via e-mail.  I’ve removed all personal details for privacy.  If you have a question, please feel free to email me through the contact form. Please be patient, I get close to a hundred messages a week, and it sometimes takes me a minute to get them all answered.

Q:  I love your bottle molds! I have a wooden plaque with a metal medallion on it. I want to make a mold of the medallion and then slump bottle bottoms. I have seen your info on kiln carving, but I want to exact replica of this medallion. How can I make this medallion mold or do I have to send it to a professional to make.
Thanks so much, I love your work and have played around with your ideas! I am definitely not an artist, but I sure can follow directions!

A:  It shouldn’t be too hard, the easiest way would be to take the plaque to your local ceramics store and tell them you need low fire whiteware clay, and show them a picture of a bottle bottom mold, and they should be able to sell you the clay.  Most stores around here will also fire the piece for you for a small fee.

Barring that, we do make custom bottle bottom molds all the time, and we can certainly do that for you.  If that sounds like an option you’d like to pursue, send me a photo of the plaque and I’ll work up a quote for you.

I’m new (under a year) to slumping bottles – wine, booze, others – with and without molds – can you explain your full fuse firing schedule so we novices can comprehend? I do not have any type of temperature gauge on my kiln.

Thanks and happy firing!!

No temperature gauge at all??  Wow.  I didn’t know that was actually possible.  Full fuse is when you take multiple pieces of the same type of glass and melt them back into a smooth solid piece of glass.  Or, if you melt a bottle all the way flat.  The stages of any firing schedule are:

Initial heating stage (to around 500F)  this is usually slow because it’s the thermal shock zone
Stabilization (around 1100F) this is just over the annealing temperature and gives the glass a chance to equalize out in temperature
Fusing (around 1550F) the temperature where the pieces of glass are liquid and melt back together (like thick honey)
Cooling – this stage is fast, usually as fast as your kiln cools all by itself.  This is the potential devit zone, so it’s not good to hang out here
Annealing – for bottle and window glass, this is 1060F.  This is the temperature that we hold at to relieve internal stress to make sure we don’t have cracking and breakage later.
More Cooling – slow cooling down to room temperature.  This is another stretch of the firing schedule where thermal shock can occur.

I hope that helps,  Jodi

Q: Yes, it does help!

And, no, no temp gauge.  It’s an older kiln with 2 low-med-hi settings.  How do you recommend monitoring the temp? Is there an accessory?
A:  I’m totally impressed that you are managing without it, I imagine there’s a fair amount of baby sitting going on.  Here is a digital pyrometer that isn’t too expensive, and may work well for you:

https://www.amazon.com/Digital-pyrometer-pottery-Thermometer-Thermocouple/dp/B00R32JKQI

My kilns all have built in pyrometers and controllers so I don’t have any experience with aftermarket ones.  The key would be to make sure it can tolerate kiln temperatures, which it seems this one will.

If you do get one, let me know what you think, I always like to know about new tools and things.

Have a great week!

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READERS:  If you have experience with an after market pyrometer and would like to share your experiences, I would love to hear them, either in the comments or directly through the contact form.  Thanks!

One thought on “Q&A Monday – 10/24/16

  1. I use a pyrometers. Works great. I’ve learned about how long it takes to reach certain temps so that I can do other things while the kiln is firing.

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