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Cracking enamels


#1

Hello to all from sunny Queensland, Australia.

I have been lurking for the last few years and appreciating and
enjoying the discussions during that time. Now I need help.

I am concentrating on enamels. I have used leaded transparent
enamels on fine silver (1 mm thick) and counter enamelled the back
(unleaded opaque). I have incorporated some fine (size) fine silver
wire into the design. The work was carried out a number of months
ago. I checked the enamels in order to set them the other day and
found that two have now developed a fine facture through the enamel.
Other pieces that I enamelled before and after are fine. The two
pieces were fired on different days.

Does anyone have a suggestion as to what the cause may be? If I
refire, will the enamels again crack after time. I am reluctant to
spend large amounts of time setting the enamels in a piece of
jewellery to then find that they have cracked after time.

Thank you for your assistance.

Anne from Aus


#2
    I am concentrating on enamels.  I have used leaded transparent
enamels on fine silver (1 mm thick) and counter enamelled the back
(unleaded opaque).  I have incorporated some fine (size) fine
silver wire into the design.   The work was carried out a number of
months ago.   I checked the enamels in order to set them the other
day and found that two have now developed a fine facture through
the enamel. 

g’day Ann - there are many reasons why that might happen - if you
care to email me some good pictures (flatbed scans will do fine @
300 dpi) I’ll see what we can sort out.

enamel@ netconnect.com.au

cheers
Allan Heywood, also in Aus


#3

Ann, there are several possibilities for your enamels developing
cracks. One of the most common is putting an enamel with a high
expansion rate over one with a lower rate of expansion. When
using colors having a high expansion rate I always use a flux which
has an even higher rate of expansion. In order to avoid any
possibility of an error, I mark the expansion rate on all my
containers of enamel. Some colors are more prone to cracking than
others— and it is essential that these be fired over a flux
having a higher rate of expansion. If you have not already done so,
you might want to take the time to run off some tests so that you
can see the results. Hope this helps. I use Thompson’s enamels
(mostly lead bearing), As well as Blythe (Johnson-Mathey).but use
lead free flux----with no problems—but I do match the enamel to
the flux having the correct (higher) rate of expansion. the colors
I have found to be most prone to cracking seem to be the transparent
lavenders, peach, and tearose. Hope this helps. it is
frustrating to have a piece finished, only to notice cracks. Good
luck. Alma


#4

hello, all i am totally new to enameling. have been decorating with
enamel the backs of settings i created out of silver and copper.
have been having trouble with cracking, esp. around the fine
cloisonnee wires i use to make my “funky plant” designs. i have not
yet made a design using all one metal, i am wondering if the heating
and cooling of the two metals (copper and silver) are creating too
much stress on the enamel (thompson, btw). i am also wondering if i
am getting the enamel too high, since it isn’t formal cloisonnee,
per se.

i am also having to torch fire all my enameling, because the kiln
trips the circuit to my shop. having fancy wiring done is
financially beyond us at this time - i would rather try to
troubleshoot with torch firing. has anyone any experience with this?

thanks in advance for the help.
susannah


#5

Susannah - I am interpreting your words “enameling on the backs of
settings” to mean the back of set stones or other objects - as with
cabachons or stones, etc? Is that correct? If so, it would be an
interesting form of decoration but would not permit counter enamel
(same amount and thickness of enamel on the opposite side of the
metal) unless you had room in the bottom of the settings for the
counter. Counter enamel is used to create equal stresses on both
sides of the metal so you don’t get cracking or breaking. Torch
firing would certainly not be impossible doing this but would make
it all more difficult because typically there is only about 25
degrees of difference between the temp at which enamel melts and the
temp of the solder used to make your settings - solder and enamel do
not mix and the solder will ruin your enamel - Maybe I am
misinterpreting what you are doing. I thought Louise Gillingham had
some good suggestions for you. Sherry Reed


#6
 have been decorating with enamel the backs of settings i created
out of silver and copper. have been having trouble with cracking 

Hi Susannah, Are you counter-enameling the reverse surface? The
enameling does cause a stress on the metal, and a counter-enamel on
the reverse provides a “pull” to balance the stress on the front.
Just a thought from my somewhat limited cloisonn=E9 experience…

Dave
Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com