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Yellow cloudiness in enamels


#1

I am having a problem with a sort of yellow cloudiness in my
enamels. When you look at it under a loupe it looks like little
bits of yellowish scum (for lack of a better word) suspended in the
enamel. I’m using Thompson enamels and a Neycraft kiln. I get the
same results on copper and silver. It is barely noticeable in the
first firing, but builds up with subsequent firings, so that by the
time a piece has been fired 4 or 5 times it really begins to affect
the colors. Anyone else experience this, or have any ideas about
what it is? Thanks, Susan


#2

Hi Susan, If you are wet packing it is possible that you have not
removed all the fines from your enamel and they are causing the
cloudiness. The only time I have had a problem with cloudiness when
working dry (sifting), is when I put a coat of flux over the
prefired enamel. For some reason this did not fire clear, but left a
cloudy film over my work. This was expecially obvious over the
transparents. If you could give more specifics about what you are
doing perhaps someone could come up with an answer that will solve
your problem. Are you working with lead free, or lead bearing
enamels or both? If working with both, are you layering them? And
if so, in what order? You can put the lead bearing over the lead
free, but not the reverse. If none of the Orchidians comes up with
a solution, you might email Tom Ellis at Thompson Enamel for
help. He is very kind and is an expert in these matters. If you do
get some satisfactory answers, please pass the along
as it will undoubtedly help others. Alma


#3

Sorry, I didn’t mean to be vague in my first message. :slight_smile: I’m using
lead-free Thompson enamels that are fairly new, I bought their
sample set just a few months ago. I have been enamelling on fine
silver, and have done tests using their clear for silver, golden
clear, medium clear, and hard clear. I have also tried some tests
on copper, both with and without silver cloisonne wires. I’m
currently sifting the enamels through a 100 screen, then washing
with distilled water. I’ve been applying them with Klyr-fire
diluted with distilled water. The only reason I mentioned the kiln
is because it is also new. Up until now I have been enamelling at
the local community college, in a very old well used kiln, and had
never noticed this particular problem. The one I recently bought is
the same model, but I had noticed a lot of powder coming from the
walls when I open and close it, so this weekend I painted the walls
and inside of the door with fiber hardener. I’ve only tested it
once since then, but had the same results. The only thing different
between this kiln and the one at the college (other than the age) is
that this one has a porcelain tray that sits in the bottom. I think
its actually a burnout tray, but I left it in there to protect the
bottom of the kiln. Thanks again, Susan


#4

I have never heard of anyone painting the walls and door of a kiln
with a fiber hardener- don’t even know what it is. What material is
covering the inside of your kiln? I am wondering if that may be part
of the problem. Didn’t you call the Neycraft company when you noticed
dust falling off the walls. Is it lined with firebrick?

I would have also vacuumed the inside if that had happened to me (or
even returned the thing). I have 2 Vcella kilns that are lined with
fire brick and do not have fall off or dust unless I scrape the
firebrick. Then it must be vacuumed. You should be using a kiln shelf
that is coated with kiln wash on the bottom of your kiln to catch the
spills. You had better talk to someone at Thompson
http://www.glass-on-metal.com/main.htm to find out about the
cloudiness of lead free enamels. I use them but not for cloisonne or
on silver. I use only leaded enamels for that.

Louise @lgillin1


#5

Hi, I will readily admit that I don’t do much firing of transparent
enamels on silver, so I’m not the expert you were looking for. You
don’t seem to be getting a lot of response on this though so I would
like to state two common problems it could be.

  1. As someone else mentioned, to get really clear enamels you need
    to remove the fines, or the powdery enamels that exist after
    grinding. You need a little bit but not as much as is normal. Tom
    Ellis did this by using 3 layers of sifting trays. 150 mesh on top,
    325 mesh in the middle and a catch pan on the bottom. You use the
    stuff that ends up in the middle tray to get the clear transparents.
    He said to discard the fines, but most of us use them as counter
    enamel instead.

  2. Many enamelists complain that they can’t get a truly clear enamel
    on silver from Thompsons. I agree that you should try Tom Ellis at
    Thompsons and ask, but don’t limit yourself to just that. You may
    also want to call Coral Shaffer at 800-596-3257 or 206-525-9271, she
    sells imported enamels that some of my friends have much better luck
    with, of course, these are not lead-free as Thompsons are.

Karen


#6
You use the  stuff that ends up in the middle tray to get the
clear transparents. 

I am using a lot of transparents and it is not enough to sift them,
you need to wash it. Put the sufted enamel in a glas or a container,
depending on how much you need to wash. Put water on it, stirr with a
glass or plastic spoon, leave for some seconds so most of the enamel
sinks to the bottom. Pour the water off, not too fast but watch the
enamel on the bottom carefully: don’t throw that away. Repeat as many
times as you need to get clean water on top. (throw the water in a
container to collect the enamel and don’t wash it away in the sink).
In the place were I live (Maastricht) the water is very hard and will
leave a cloudy residu in the enamel, so I end up with washing twice
with destilled water, the kind you can use to fill the steam ironing
iron with. Hope this helps, just done a lot of transparents and they
were all perfectly clear, also the Thompsons can become clear! Needs
to be fired at the right temperature too, and be careful no dust can
fall in while it is drying. I hate it, but you must always work in a
clear worspace. (There is no place in my house as clean as my
enameling space while I am enameling).

Hope this helps, good luck! Marleen.
Marleen B.Berg
Aventijnhof 11
6215 ES Maastricht
Nederland
website: http://www.mbberg.com/


#7

If you sift out the 325 fines, you should get clear leaded
transparents. Wash several times or until the water is no longer
milky.

You can get clear enamel on silver with Thompson’s if you use the
leaded. What they now produce is lead free. Many of us are still
using the old leaded Thompson enamels. I never use leadfree on silver,
so could not attest to that.

Coral sells the Japanese leaded enamels. I have found they have lots
of fines. You need to sift out the very fine enamel that falls from
the 325 sifter. Wash also before using. You can also get the French
leaded enamels (Cristallerie St. Paul) which are wonderful on silver.
Call Bavano of Cheshire in CT. 800-847-3192 Louise
@lgillin1


#8

In my recent and limited experience with Thompsons enamels: I did a
few pieces of cloisonne with transparents. The first piece came out
very cloudy. My teacher (Deb Lozier) and I assessed that the
problems weRe: The enamel was not sifted (sounds like you covered
that). 2: My layers were too thick (much more important than I
realized). 3: I wasn’t fireing at high enough of an oven (some
transparents, like tr ivory beige don’t seem to strike thier true
color until 1600 degrees).

Following all of this I remade my original piece with wonderful
results. The thinner layers really helped.

Amy O’Connell
Amy O’Connell Jewelry
http://LapidaryArt.com


#9

When troubleshooting various problems with enamels, enameling (or
with the enamelist) - first try
http://www.glass-on-metal.com/ask_the_experts/index.htm & also, have
a look at http://www.enamellers.nl/english/index.html Also, try your
public library for books by such authors as Kenneth Bates or Oppi
Untracht (and many others). Most likely, the same difficulty has
already been encountered before by someone. The archives of the above
URL links are very comprehensive. Lastly, there are ‘cool’ vs.'warm’
metals too; often the results of ‘warm’ colors on ‘cool’ metals (and
visa versa) produce quite differing results. Regards, Mark


#10

Hi Susan, You have received some very good advice regarding the
thinness of the enamel layers and sifting out the fines and washing
well. I don’t think anyone mentioned that many of the transparent
reds, pinks, oranges, yellows, and some purples will become cloudy
and get a yellowish scummy appearance if fired directly on silver.
They can be used successfully over a thin layer of flux though.

Jenny.


#11

Thanks to everyone for your suggestions. I have been sifting and
washing, but will concentrate more on thinner layers and see if that
makes a difference. I’ve also visited the websites that someone
suggested, and read through their troubleshooting columns and gotten
some good advice. Hopefully soon I’ll be turning out incredibly
gorgeous enamels. :slight_smile:

Susan


#12

Susan,

If the problem does not clear up, it could be the Thompson’s
unleaded enamels themselves. The high firing temperature of 1600 may
be the solution, as these enamels “mature” at high temperatures. As a
beginner I used them in cloisonn=E9 on silver, and the results were
similar to what you’ve been experiencing. 1450 as the "right"
temperature for firing is the standard, so I did not try the higher
temperatures until much later, as no one suggested it to me. The
Japanese enamels are much more user friendly, formulated to almost
uniformly mature and clear around 1450. When I teach they are the
enamels I recommend for beginners.

Alana Clearlake