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Firing bronze metal clay for patina look


#1

Need some advice about Bronze Metal Clay

I recently decided to give the new bronze metal clay a try. Found it
easier to work with, consistency-wise, than instructions had warned.
Everything went well up to the firing. I fired it in the coal
medium, wanting the patina, as advertised. Programmed my digital kiln
for the right ramp time, holding time, etc. When it finally cooled
and I anxiously dug them out - they were different dark colors but it
was a really matte, thick and “dusty” finish that obscured the
designs in the pieces. I tried burnishing, buffing, etc…which took
off all the color of course, so they’re just bronze-colored now. with
a little greenish hue in the recesses. What in the world went wrong?
I dried them on a hot plate for a long time, so I think they were
properly dried. Oh, and some of the pieces that were meant to be
pairs - as in earrings - shrank at a different rate, so no longer
match.

Any suggestions would be appreciated.
Linda Gebert
www.lindagebert.com


#2

About the bronze clay, patina, and different shrinkage: I have been
working with bronze clay since it came out (as well as silver and now
copper clay) It can be very frustrating. Just like you have now
experienced. I have read everything and done everything and tried
everything and my batches in the kiln are still unpredictable. I
have somethings in the same firing turnout beautifully and something
else be completely ruined, not sinter, melt, bubble, turn to dust,
crack, get really small, stay really big - you name it. Keep
experimenting. I ramp at 250 degrees instead of 500 degrees that
seems to have helped some of the sinter problems I was having. You
can refire your pieces to try and get the patina you want and make
sure you have the correct charcoal for patina because there are two
kinds. Cooltools.us has the best photos of mishaps with bronze clay
during firing and how to correct them. When I make pieces for
earrings I make more than one set. I make several just to insure some
of them turn out close to the same size. Just this week I considered
not using bronze clay anymore because I was so frustrated with one
batch that I need to work and of course I made it over twice. I am
losing my patience with it and I don’t have the time to waste to do
things twice or even three times. Sorry so long winded. The stuff is
fun but I have not found a way to predict it yet. I hope some others
commentand maybe I can learn something I have not yet discovered.

Good luck :slight_smile: Joy


#3

Linda,

You might want to try the forums at PMC guild website. My friend
Catherine Davies Paetz and others has recently been doing extensive
testing of the copper and bronze clay. She is an active contributor
there, and may be able to give suggestions.

Kim


#4

I’d say, put 'em back in the charcoal and fire again. If they’re
different sizes, at least one is not sintered properly.

They should shrink around 25%. Re-firing will change the colors,
though there’s no way I know of to guarantee good colors.

Noel


#5

You will find many people with bronze clay experience on the Yahoo
group Metal Clay gallery. Also check out Marco Fleseri’s blog for
some firing experiments he published. fleseri.com

See the BronzClay Squidoo Lens, and the blog of Hadar Jacobson.

Specifically for your problem of uneven shrinkage – you might try
the 2 phase firing – with open shelf firing first for maximum
shrinkage.

Elaine
http://www.CreativeTextureTools.com


#6

Welcome to the world of bronz clay. Bronze clay is rougher than
silver clay and doesn’t smooth out before firing to quite the same
extent, although thorough prep before firing will eliminate some of
the “dust” and rough exterior you experienced. I usually don’t care
about the colors from the kiln. I brush and tumble my pieces and if
any color remains, it’s just a plus. As for the earrings shrinking
and firing to different sizes, that can happen because of different
temperatures in the kiln and different internal structure in the
clay. Minute differences in thickness or internal consistency will
result in different results. If you want two pieces to be nearly
identical, you will need to make them from the same piece of rolled
clay so that they are as identical as possible, and place them in as
much of the same position when firing as possible. I try to put
items vertically in the carbon, as close to the back of the firing
container as I can. Bronz clay is not as predictable as silver clay,
so it is an experience of discovery and actually a lot of fun.

Sandra Graves, Isis Rising
Artistic Endeavors with Wings of Light


#7

There is a wonderful DVD from Dragon Glass, Aventures in Bronzclay &
Copprclay, purchased through Art Clay World. It shows how to patina
bronze clay using a torch and fiber blanket. The bronze clay is
placed on the fiber blanket, heated until the desired patina is
reached then immediately smother with another piece of fire blanket.
If the piece gets to dark, let it cool off, and start again.

Cin Hollins


#8

I have just finished my “experiments” with bronze clay…I had much
heartache in the beginning, especially with pieces coming out
different sizes—unmatched earrings…!!!

I posted my questions to the Metal Clay group and Jacki Trudy came
to my rescue (angel award.!)… She told me to re-fire…I did,
re-fired the larger pieces and they came out exactly the same size as
the other smaller ones…

I also had problems with pieces turning to dust — that seems I
solved by a firing schedule of 275 an hour to 1500, hold for 3.5
hours… I fire all my pieces while I sleep… that seems to have
corrected the “dust” problem… as far as color — I do use the
coco carbon, once in awhile, unpredictably, I get a nicely colored
piece from the carbon, but lately I’ve been tumbling to polish, then
brushing it with a torch for color… Some of my prettier pieces are
made from bronze clay, and while it seems I have overcome the two
biggest hurdles–dust and sizing–I still don’t fully trust it, and
really don’t like the long firing schedule, or the shrinkage… I
will use it for speciality items, maybe if I get in the mood, but I’m
back to silver clay… I might combine pieces with both clays… Now
I’m off to try copper…

Blessings, Margaret


#9

Thanks to all who had helpful suggestions regarding the Bronze Metal
Clay and firing. I’m beginning to think I’m not all that enamored of
the look of it anyhow. I did polish the pieces, and then do some
liver of sulfur patina… Refiring the larger of the two earring
pieces is a good suggestion, as several told me that would help in
getting them the same size. And several said ramping the kiln more
slowly, like 250 degrees an hour helps too, but I’m not crazy about
putting so much “wear and tear” on my Paragon digital kiln. I use it
for enameling jewelry, and pmc silver mostly. I already had to
replace the “innards” two months after the warranty was up, (wouldn’t
you know?) because a wire had burned out. BTW - the firing pan has
the most gorgeous blue to fuschia patina on it - go figure!

Linda Gebert
www.lindagebert.com


#10

This has probably been covered before, but why are people using
bronze clay as opposed to casting?

It sounds like it’s difficult to get what you want, and rife with
failure, at least until you have done a significant amount of
experimentation. At more that 5 times the cost of bronze casting
grain, and requiring a kiln and lots of specific hardware, the bulk
of the expense of investing in a casting rig should be offset after
the first few pounds of bronze have been cast.

Am I missing something?

Jason


#11
This has probably been covered before, but why are people using
bronze clay as opposed to casting? It sounds like it's difficult to
get what you want, and rife with failure, at least until you have
done a significant amount of experimentation. 

Why does the mountain climber climb the mountain? Because it is
there. Why does the bank robber rob the bank. Because that’s where
the money is.

For those of us who work with (silver) metal clay, the BronzClay and
CopprClay offer the next challenge. It’s fun to work with – it’s
different from the silver clay. It’s also affordable enough to let
kids work with it – something I’ve done.

It’s still pretty new, some people try it and decide it’s not for
them. It’s highest and best use, to borrow a real estate term, has
not yet been determined.

But why do we try? Because it is there.

Elaine
http://www.CreativeTextureTools.com


#12
This has probably been covered before, but why are people using
bronze clay as opposed to casting? It sounds like it's difficult to
get what you want, and rife with failure, at least until you have
done a significant amount of experimentation. At more that 5 times
the cost of bronze casting grain, and requiring a kiln and lots of
specific hardware, the bulk of the expense of investing in a
casting rig should be offset after the first few pounds of bronze
have been cast. Am I missing something? 

Jason, I think the main thing you’re missing is that BronzClay is
simply a different material that artists want to use. Most folk
working with it are crafters or entry level jewelry makers, older
folks, folks working out of their homes and others who are simply
not interested in going the casting route for a variety of reasons.

Some folks just like working with new technology and are happy to
experiment to find the path that best fits their work ethic. Both
methods are great for creating bronze jewelry, different strokes and
all that.

Lora


#13
I think the main thing you're missing is that BronzClay is simply a
different material that artists want to use. Most folk working with
it are crafters or entry level jewelry makers, older folks, folks
working out of their homes and others who are simply not interested
in going the casting route for a variety of reasons. Some folks
just like working with new technology and are happy to experiment
to find the path that best fits their work ethic. Both methods are
great for creating bronze jewelry, different strokes and all that. 

I guess my feeling is that, in general, when a new technology comes
along and the only stated improvement or benefit is that it’s new,
there isn’t any real point to it. It is entirely likely that bronze
clay and copper clay have benefits over existing materials, however
I’m unaware of them. The expense and difficulty as compared to
casting seems similar, not to mention that the ultimate durability
of sinters tend to be lower than solid counterparts.

I don’t see how having a kiln in your home and all the equipment for
sintering the clay would be a significant improvement over a kiln
and a small centrifugal or vacuum caster. It seems the only solid
benefit is the complete lack of need for a torch, unless you
electromelt, but wouldn’t people want to be able to solder findings
to their clay pieces as well?

I’m interested in any new materials that I might find use for, but
as of yet I haven’t heard of any sound benefit from bronze clay.
Someone please prove me wrong.

Jason


#14

Jason, again, I think you’re missing the point. It’s just another
material. Another method. It’s not better. It’s not worse. If you
have a method that works well for you, then there’s no reason for
you to look into metal clays.

There is much more involved with the casting process than with the
metal clay process, even including the one additional step needed
for bronze and copper clays. To understand completely, take a class.
Not to assume you’ll want to incorporate the method into your own
work, just for kicks and understanding.

I’ve taken a hydraulic press class from Cynthia Eid. I knew before
signing up that I’d never buy a press or use the technique. But I
wanted to explore and stretch my knowledge. It was an amazing class
with an amazing artist, and if I had the money for the equipment and
the space to set it up - I might play with it a little more. But for
me, making dimensional objects with metal clay is so simple that I’d
only press for fun.

Lora


#15
I don't see how having a kiln in your home and all the equipment
for sintering the clay would be a significant improvement over a
kiln and a small centrifugal or vacuum caster. It seems the only
solid benefit is the complete lack of need for a torch, unless you
electromelt, but wouldn't people want to be able to solder
findings to their clay pieces as well? 

I’d like to weigh on in this, although a somewhat similar response
has already been given. For me, and I think there are a lot of
people in the same boat as me, the significant improvement of bronze
(or other metal) clay is the knowledge to work with it. I have
absolutely no knowledge of how to cast pieces, other than heating
metal to a liquid state and pouring it into a mold. On the basis of
that alone, I’m pretty much doomed to failure if I attempt to cast
something. But thanks to having Play-doh during my childhood, I’m
already decently equipped to handle metal clay. Almost anything in my
house can become a tool and the most limiting factor is my
imagination. For those of us that lack the knowledge, equipment,
budget and space to embark on casting our own pieces, metal clay is a
fantastic way to help us get detailed and/or complex designs out of
our head and into reality.

Cheers,
Cheree


#16
I don't see how having a kiln in your home and all the equipment
for sintering the clay would be a significant improvement over a
kiln and a small centrifugal or vacuum caster

As it happens, a convenient demonstration has just presented itself
to show the sort of thing you would have a much harder time doing
by traditional casting or other means. Take a look at the most recent
entry on Hadar Jacobson’s blog: http://www.artinsilver.com/blog/

Whatever your opinion, I think anyone would have to acknowledge that
metal clay is a new and different way of working, and not a
substitute for casting or anything else.

Noel


#17

Cheree

I am trained in metal and also have used my hands to be a hairdresser
when times were tough. Arthritis, Diabetes and a kidney transplant
help me still be able to create the same quality pieces with alot
less tear on my hands and alot less exposure to toxic chemicals. I
see no difference from when I was in college for metals to creating
something in wax and having it cast. Mater of fact sometimes I have a
mold made of my clay pieces and have them cast.

What’s the difference what we use to create, its what you do with
the materail. Whether I’m drawing or painting or creating something
out of metal clay, its still my voice, my mark so why so much about
the medium? Just a thought!

thanks,
Linda Reboh