After firing copper clay break easily

Jewelry Discussion
1

I am having trouble getting Copper Clay (from Rio Grande) to fully
sinter. After firing, the pieces are flexible and break easily, some
pieces have broken apart and are of powdery consistancy. I use the
Paragon PMC kiln with the programable controller. I have used the Rio
Grande firing instructions.

Any ideas?
MRP

2 
I am having trouble getting Copper Clay (from Rio Grande) to fully
sinter....I have used the Rio Grande firing instructions.

But which directions? They have changed over time… Check out Pam
East’s directions at pameast.net. Also check out the current
directions on copprclay.com. The printed directions I saw in some
that I tried had an omission regarding the two stage firing that
gives the best results.

Mary Ellin D’Agostino, PhD
www.medacreations.com

3

Either the temperature is too low or your firing is too short to get
the copper to sinter properly. I wouldincrease the temperature by
10deg and the time my 10 minutes and see how it affects your results.
If your pieces are quite large then increase the time considerably
more.

4 
am having trouble getting Copper Clay (from Rio Grande) to fully
sinter. After firing, the pieces are flexible and break easily

Many of us are using a slightly different firing schedule than the
one published by Rio. One technique that seems to help is placement
in the stainless steel box – using a smaller box and putting fewer
pieces in it does consistently result in better firings.

You will find the blog of Hadar Jacabson quite helpful on this
question.

Elaine
http://www.CreativeTextureTools.com

5

myra, you don’t mention what firing schedule you are using or how
big/thick your pieces are. here’s a fairly recent schedule that may
work better:

BC firing:

  1. in kiln on shelf (open air) firing:

    a) RA = 250F
    b) Temp = 550F
    c) hold time = 30 minutes

  2. second firing in carbon

    a) RA 1 = full speed
    b) Temp 1 = 1100F
    c) Hold 1 = 0
    d) RA 2 = 250F
    e) Temp 1 = 1490 (1516 with muffle kiln)
    f) Hold 2 = 3 hours

CC firing:

same as above for first open air firing

  1. second firing in carbon (coconut preferred)

    a) RA1 = full speed
    b) Temp = 1750F (some are firing at 1650, but most of the beta
    testers are firing at 1750)
    c) Hold = 3 hours

6

For many years I purchased sheet and casting silver from the same
place. Over the years their prices have gone up and up, as has the
price of silver. Their prices have gone up at a higher rate than the
price of silver. I am now looking for an alternate source of sheet
and casting silver. I would like some suggestions on sources. I am
also replacing, in the not so distant future, my Smiths
Acetylene/air torch. If anyone has suggestions for replacing an older
torch I would appreciate it.

Jon H

7

Hi Jon,

For many years I purchased sheet and casting silver from the same
place. Over the years their prices have gone up and up, as has the
price of silver. Their prices have gone up at a higher rate than
the price of silver. I am now looking for an alternate source of
sheet and casting silver. I would like some suggestions on sources.
I am also replacing, in the not so distant future, my Smiths
Acetylene/air torch.

I’d recommend Hauser & Miller (hauserandmiller.com) in St Louis as a
supplier of precious metal products. They’ve been in business for
over 100 yrs & are a refiner & mfgr of precious metal products.

Just a happy customer.
Dave

8

There has been a lot of experimentation with this, and the concensus
is that you need a two-stage firing system to fully sinter the
CopprClay from Rio.

I suggest the following schedule: 1st phase - open shelf, 480F to
555F with a 1 hour hold. 2nd phase - in carbon, full to 1650F with a
3.5 hour hold. I also allow my clay to cool in the kiln overnight
and remove it in the morning. That keeps any oxidation problems away.

You may also want to look into the new Art Clay product, Art Clay
Copper. ACC can be kiln fired, but can also be torch fired, and needs
less time to sinter completely.

Sandra Graves, Isis Rising

9

For all of you delving into metal clay - there is a dedicated forum
at metalclay yahoo groups. There you will find an entire encyclopedia
of in the archives, and a membership consisting of
helpful, knowledgeable artists. There are also a variety of Squidoo
Lens’ focused on both silver and bronze clays with a ton of up to
date

Precious Metal Clay (PMC) and Art Clay Silver and Gold - FeltMagnet &
BRONZclay Bronze Metal Clay Jewelry Techniques - FeltMagnet

Information about the new copper and bronze clays is changing almost
daily. There are two different copper clay manufacturers and three
bronze ones. The firing schedules are still being worked on to
discover the best firing method. These clays have only been out for a
year. Silver clay has been on the market for about 15 years. We’re
still learning. It’s an exciting time and we’re all testers!

Keep trying different methods and firing schedules and you’ll get it
in no time.

Lora