3-D Art Clay tech

[Suzanne]

Thanks, Metalman, for your reply....
I did a try (before your posting), which ended in the results you described. It was a great "show" to see the burning object '>
Having created it with two holes (to pull a necklace through and to prevent it from exploding...) it teared nevertheless at two places...   Also, I got the impression, the thickness of the object was much thinner... (it had 9 really thick layers???)
Is it possible, that the object had melted inside a bit?
Many greetings,
Suzanne

[Suzanne]

Dear Rings&Things Members,
as a really Newbie concerning ArtClay I would like to know, if anyone of you ever experimented with firing (small) ACS pieces with a "heart" of CorkClay by torch? I know, the official instruction sheet says "NO" to this, but '>
Sorry for my english...
Suzanne

[Metalman]

It is possible that it melted.  That would depend on your torch controll mostly.  It is a delicate balance. It is hard for me to say with out seeing the piece.  
But......  experimenting is reasonable, these are new materials, there is a lot to learn.  Keep asking and trying.
Let me know how I can help.

[Metalman]

Suzanne,
Sorry I am so late in replying.  The problem with firing the cork clay with the torch will be the extended burning of the cork.  With the torch temperatures, the organic material will tend burn very quickly which has the potential of flaring up or even exploding depending on whether the burning gases are trapped or not. In addition, the burning of the organic material will change your temperature control  potentially causing your piece to overheat and melt.
You can/could experiment with this but I would approach this with extreme caution and care.  I am fairly experienced with torches, welding, soldering and fire in general and I would try to work for kiln access if I could.

[CC Designs]

I have been working with metal clay for a few years.  I'm beginning to experiment with larger hollow forms, and I'm curious which "cores" people find most useful, and most importantly, do not sag when fired.  (I do ventilate the area where my kiln is located.)
I'd appreciate any info, thanks.

[Metalman]

Regarding cores -- first thought/question is how large?
I have had good results with the cork clay up to about 1" in diameter and 3 to 4" in length.  You can also use many natural materials, meaning that they are 'organic' materials which will burn away almost completely [leaving a small amount of ash] If the form is almost completely enclosed, with very few small holes, it is my impression that it is best to '> fire slow so as to allow the gases to dissipate as the materials burn off; this is how I fire it.
If you are working larger than this, you can build an internal structure of metal clay, fire it in fiber blanket -- then adjust the structure, build the cork clay around it and do your surface design, then fire again.  I have done some experiments along these lines with good results.  This is the experimental edge so you will have to play it out a bit. One problem that does arise is shrinkage factors.  I am working with Art Clay Silver and some times need to do a third firing [or more],  to patch and repair. But the end results have been fine.
A further idea would be to work with porcelain or bisque ceramic 'armatures'. The Art Clay Silver 650 Overlay Paste works great and I have had good results using the overlay paste as an interface to regular clay elements. Again shrinkage considerations will apply.
A further note:  there are paper clay products which you can use but some of them contain minerals.  Any thing with minerals [non-organic] will not burn out properly. This can cause problems or be an area to experiment with  

[silverghost]

Yes, you can use a soft fiber blanket to support during firing. When firing Art Clay object with burnable core (like cork clay) to make hollow piece, do not cover entire piece, or the piece may deform or melt, because of the heat retained inside the blanket may become too high. Support the piece with the soft fiber blanket, but leave the ventilation space.

We now carry those blankets R&T # 69-181

[IrvInChi]

Can materials such as a soft fiber blanket be used to support an irregular object during firing?