metal former question

Started by jackiesimmonds, January 14, 2015, 07:41:51 PM

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jackiesimmonds

would it be possible to use a COPPER former for drop vases?  I know most people use stainless steel, but I have a copper vessel which is dented, so not usable for my work with enamel on copper, and I am wondering if I could use it as a former, if covered in Boron Nitrate?

Moira HFG

That's an interesting idea. Well, the melting point of copper is a bit higher than glass - around 1060ÂșC. But unlike stainless steel, it will oxidise, so glass might stick whatever you cover it with.

One way to find out.....  :)

I would do it in a steel tray or something, to protect the kiln.

Pat from Canvey

Wouldn't the copper deform through annealing at glass drop temperatures? For drop vases rather than slump molds, I use ceramic rings as I think do most people, I could be wrong. See http://www.creativeglassshop.co.uk/category/713/drop-outs.html

jackiesimmonds

 The copper oxide issue does worry me a bit, I don't want to ruin my new kiln!  CuO is SO messy.  And you may well be right about the copper deforming...when it is soft, it can be easily shaped, so yes, I suspect this could be an issue.  Paraticularly with a heavy piece of glass sitting on top of it.  I think I might bin this idea!

I spent AGES on line yesterday trying to find drape and former molds here in the uk, either in stainless steel or bisque - I found a couple of formers, but my kiln would need to be 9" deep and I have a Hobbyfuser, which is not.  The others were only 4" high....so would only make a tiny drop vase.   I also fancy having a fluted bowl-shape drape mould, wide but shallow - found them on American sites, but nothing here.    The shipping cost more than the mould!!
I think the answer is to get someone to make me something in bisque, or try that myself.  I have worked with clay, just never tried firing myself, it was all done for me.  I would have to find out about firing temperatures etc.

For the drop vase, can you please tell me if stainless steel beakers, like those sold in camping shops, or Tesco, would be OK?

I didn't really want the drop moulds, they don't give the same lovely folded effect you get with a former.   Tho I will learn to use these properly later in the year, I managed to get onto an Amanda Simmons Masterclass for drop-out vases - yay!


Pat from Canvey


Pat from Canvey

#5
Stainless steel should be OK provided you can get the bat wash to stick or try boron nitride, (expensive). I sometimes use strips of copper to form pendants and just hoover out the kiln afterwards to take out the oxides.

jackiesimmonds

gosh, Pat, you are a mine of information!  thank you very much.  Wish you lived next door.........

jackiesimmonds

hmmm Cone 4?

Know nothing about cones, so that website was confusing for me.

Howsabout this - does it make sense to anyone?

   Step Rate temp hold
1. 200   80      2.0
2. 200  150     2.0
3. 300  550       0
4. 60   615        0
5. 180 1040 5 minutes
This apparently allows for drying, removal of chemically bonded water, slow transition through quartz inversion and cone 04 bisque.

Zeldazog

#8
Don't think a Hobbyfuser goes hot enough to fire stoneware clay to bisque does it?

Been a while since I did a clay firing, but that looks about right to me from memory

Clay work (like glass really) is as much about heat work as it is about final temperature.  So, holding for longer at a lower temperature can yield similar results to a quick higher firing, which is one reason why cones are used.  

Cones are usually stood up in a lump of clay in the kiln, and when they droop over, they've had the correct amount of heat work.  The kilns we used at uni were nearly all digitally controlled (apart from the gas one, that was a monitor it one, but great fun when doing reduction firings  ;D) -  but the ceramics technician always used cones to check the firings.  More basic ceramics kilns use a kiln sitter which responds to the cone's movement.
 
This explains it better:

http://pottery.about.com/od/temperatureclayglazes/tp/pyrocones.htm  
http://ceramicartsdaily.org/firing-techniques/electric-kiln-firing/ten-basics-of-firing-electric-kilns/

Quartz inversion is the point where the clay body changes it's structure, and it involves a rapid expansion, so not done carefully will result in cracked clay.

jackiesimmonds

ah, did not notice that final temperature......     

it all sounds worrisome to me, the kiln is brand new and I am still making friends with it.

I looked at the handbook, it says "Temperature Setting Range 0 - 1320C"   so it does look like it could be OK.

but am gonna try to find someone else to make these for me, I think!