Gold??

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Candy Kahn
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Gold??

Post by Candy Kahn »

I am making a piece where I want the center to be a light gold color. I have researched all the info in the archives re mica and am concerned that if I do make a center piece that is mica (capped with clear) and then combine it with all the other pieces and fire to 1500 and hold for 20 minutes that the mica will burn off. Is this true? And, if so, are there any paints/enamels that will give me the same look as 22 kt gold?

Thanks in advance for your input.

candy in oregon
Candy Kahn
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Brock
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Post by Brock »

Cynthia

Re: Gold??

Post by Cynthia »

Candy Kahn wrote:... if I do make a center piece that is mica (capped with clear) and then combine it with all the other pieces and fire to 1500 and hold for 20 minutes that the mica will burn off. Is this true?...
The metallic colored micas should hold up. Just be certain that you apply it thinly to prevent trapping air. When you sandwich it from the get go, it can be very beautiful and interesting. But if you apply it in clumps, it can create a pocket of air that will expand when fired (not good). Do a few test squares with the different colored metallics to find the right tone of gold and see how thick or thin you need to lay it onto the base glass.
Tom White
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Post by Tom White »

Liquid bright gold for ceramic items can be applied to the top surface of your fused item then refired to 1300 -1350 F to produce the metalic gold area on the top surface of your item.

Best wishes,
Tom in Texas
Geri Comstock
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Post by Geri Comstock »

The golds luster used for ceramics are not food safe, so if your piece is
to be used for food, I wouldn't use them.

Geri
Tom White
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Post by Tom White »

Geri, what basis do you have for saying "The golds luster used for ceramics are not food safe"? In the world of ceramics the term "non toxic" refers to the material as supplied in the bottle while the term "food safe" refers to the suitability of the product for food contact after firing to the proper maturity temperature for the product. With that distinction even some glazes which contain lead in the formula are not considered non toxic in the bottle but are rated food safe after firing correctly because any lead released is below the FDA specifications for the dish it is applied to. While the gold luster is certainly not non toxic in the bottle because of the solvents needed to apply the luster to the desired surface the fired product is a thin film of at least 22 karat gold bonded to the glaze surface. I am not aware of any lead or heavy metals that can be released from the fired gold film. The PDF file http://www.maycocolors.com/catalog/colorform9_03.pdf from Mayco Colors lists Bright gold, White gold and Mother of pearl all as food safe on page seven. If you have specific information that indicates that fired gold luster is not safe for food contact surfaces I would like to see it since I sell these products in my business and I need to be aware of which products are rated food safe and which ones are not suitable for application on food contact surfaces.

Best wishes,
Tom in Texas
Geri Comstock
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Post by Geri Comstock »

I don't know anything about the brands of lustres that you sell...never seen them, never tried them.

However, I was informed by a potter friend of mine some years ago that gold lustre (I suspect she was referring to Hanovia and Duncan brands because those are two that are often used by potters) is not food safe. I believe she said it's because they contain cadmium that can leach out into food.

If a glass artist is planning on using anything on glass food bearing surfaces, it's important to find out if they're food safe, hence my warning.

Geri
Tom White
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Post by Tom White »

Geri, I think that either your potter friend was misinformed or else that the formulation for the gold luster has changed since she obtained her information. Duncan Ceramics in their page for ceramic retailers titled "Learning About Premium Gold" located at http://www.duncanceramics.com/ceramics/ ... 8&MID=5221
clearly state " 2. Duncan Overglazes can be used on surfaces that come into contact with food and drink."
In addition the MSDS for this product located on the web at http://www.duncan-enterprises.com/compa ... _IPPHN.pdf
lists only a propritary organo chromium compound as the only metalic component of the product that is listed as a hazardous component. Cadmium is not listed as a part of this product. Cadmium is a component of Duncan's Red Coat Underglazes and is listed as a hazardous component in this product even though it is present only in a frit used to make the product. The MSDS for this prodsuct is located at http://www.duncan-enterprises.com/compa ... _FKAGD.pdf

As I said since I sell these products from Duncan, Mayco and Hanovia in my hobby ceramic studio I feel that I must be informed obout their proper use and any limitations of the products for use on food contact surfaces. I try to stay informed and guide my customers correctly in using the products I sell. Food safety and the strict adherance to only non toxic products for use by children grades K-6 are very sensitive issues with me, moreso for my own concern for my customer's safety than for the obvious product liability issues. I attempt to advise my customers of the necesity to use a food safe finish on any item they purchase which might be used with food and I am adimant about only non toxic products for grade school children working on fund raiser projects to be auctioned for PTA funds. I do not want to be nit picking about the use of ceramic products that I am familiar with but I feel it is my duty to try to provide correct scientific information about them. I hope I am as quick to respond to improper uses and information about unsafe practices as I am to statements I think are incorrect.

Best wishes,
Tom in Texas
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Post by Geri Comstock »

Tom - Thanks for checking this out. Did you find any info on Hanovia lustres?

Geri
Tom White
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Post by Tom White »

Geri, I could not find any MSDS from Hanovia on the web.

Best wishes,
Tom in Texas
Bert Weiss
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Post by Bert Weiss »

Geri

Using simple common sense, your friend must be wrong. Golld lusters are used routinely on glassware and pottery used in direct copntact with food. These have been used for centuries and have not disappeared from the marketplace in recent paranoid years.

Gold Micas will not burn out at High temps. They will withstand higher temps than real gold. The catch is that they don't work well when capped with clear glass, The biggest pop from gold mica is on the surface. System 90 and 96 glasses get soft enough to stick gold micas. Float glass requires the addition of some clear flux to stick the mica.
Bert

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Geri Comstock
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Post by Geri Comstock »

Actually, Bert, common sense doesn't work. I've seen a number of ceramic pieces decorated with gold lustre that are labeled as being for decorative use only. Perhaps it's the glaze. Maybe it's the lustre. Who knows?

Geri
Cynthia

Post by Cynthia »

Bert Weiss wrote:Gold Micas will not burn out at High temps. They will withstand higher temps than real gold. The catch is that they don't work well when capped with clear glass, The biggest pop from gold mica is on the surface. System 90 and 96 glasses get soft enough to stick gold micas. Float glass requires the addition of some clear flux to stick the mica.
Might depend upon your definition of what does and doesn't work well? :wink: I kinda like how mica's look when capped. It's all in the application though and what end result you are shooting for visually. My biggest caution is that if you pile it on too thick, you get trapped air...and that isn't always desirable.

http://community.webshots.com/photo/759 ... 1908iavVio

This link shows a panel piece with mica on transparent amber glass and capped with clear. Gold, copper and untreated micas are the colors you are seeing in the mica inclusions.

PS. Mica is food safe. It's what gives your lipstick it's shimmer and eyeshadow it's glimmer. Not a good idea to inhale it though :shock:

I believe that the Hanovia precious metal lusters are food safe. The solvents are completely burned off in the firing leaving only the precious metals and none of those are heavy metals...

You can cap these too if in doubt, and in subsequent firings, you can take them up to higher than maturing temps and they remain in tact.

Lots of safe options for Candy to try.
Bert Weiss
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Post by Bert Weiss »

Geri Comstock wrote:Actually, Bert, common sense doesn't work. I've seen a number of ceramic pieces decorated with gold lustre that are labeled as being for decorative use only. Perhaps it's the glaze. Maybe it's the lustre. Who knows?

Geri
I'm still sticking to my common sense. Perhaps there were factors other than the gold that made those pieces decorative only. Lenox uses gold on glasses and plates. They are very concerned with health and safety.
Bert

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Post by Geri Comstock »

Bert Weiss wrote:
Geri Comstock wrote:Actually, Bert, common sense doesn't work. I've seen a number of ceramic pieces decorated with gold lustre that are labeled as being for decorative use only. Perhaps it's the glaze. Maybe it's the lustre. Who knows?

Geri
I'm still sticking to my common sense. Perhaps there were factors other than the gold that made those pieces decorative only. Lenox uses gold on glasses and plates. They are very concerned with health and safety.
The syllogism you're using to come to this conclusion doesn't follow, Bert.

We don't know what kind of gold lustre that Lennox and others use on their china. For all any of us know, it's a mixture of their own and not one of the ones that commonly available now. Tom found data that shows Duncan and that other brand he sells are food safe. That's wonderful news! I will no longer hesitate to use them on food bearing surfaces.

Here's a different example of why "common sense" isn't a good idea when it comes to safety...just because someone uses a food-safe red glaze on pottery doesn't mean that all red glazes are food safe. Some of the ones used in the 30's and 40's contained uranium. Others contain lead and aren't used in the US anymore for food bearing pottery.

Here's a glass example...Spray A and SuperSpray are both overglzes. Spray A isn't food safe because it contains lead. SuperSpray is food safe. But just because SuperSpray is food safe, it doesn't follow that Spray A is also food-safe.

My friend may or may not have been mistaken about gold lustres. She told me this probably 10 or 11 years ago. They may have been reformulated. We just don't know.

My point is that if you don't know for sure that the brand of whatever you're using is food safe, it's better not to use it until you know for sure.


Geri
Bert Weiss
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Post by Bert Weiss »

Geri

This is getting tedious. I know for a fact that Lenox uses Ferro gold lusters on their glass and pottery. They probably use other manufacturers as well. Annie glass does also. Both are food contact consumer products.

I believe that my logic is rock solid. If a large company is selling products for food contact with gold fired on to them, the gold that they are using is food safe. I would bet large sums of money on this logic.

I am now guessing that Hannovia gold luster is also food safe. That is probably not too difficult to verify.

You logic does not follow mine. I know that Spray A and superspray are both overglazes and one is food safe and one is not. What I am saying is that if somebody uses food safe gold luster and then sprays with SprayA, it would follow that their product is no longer food safe.
Bert

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Candy Kahn
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Thanks

Post by Candy Kahn »

thanks everyone for your replies and thank you cynthia for posting your picture illustrating your use of mica

i will have to make more test tiles

interesting topic re food safe - don't have to be concerned on this one since it's a small table top

thanks again,

candy
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Bert Weiss
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Post by Bert Weiss »

Geri

I didn't make this clear enough. I was at the Ferro factory where they make or distribute (not sure exactly which) their gold lusters. In the lab they had pieces from Lenox and Annie Glass. I was told that those companies were using Ferro's gold lusters on their products. I didn't make this up. If I get some time HA, I'll call and ask somebody in the MSDS dept for precise info.

I'm not positive, but I think that Ferro's gold luster line is from their division that was originally Deguza and is made in Germany. Their major competitor is Hereaus, Engelhard, Hannovia. I'm quite sure that their gold lusters are totally comparable.
Bert

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Kevin Midgley
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Post by Kevin Midgley »

Bert Weiss wrote:Geri

I'm not positive, but I think that Ferro's gold luster line is from their division that was originally Deguza and is made in Germany. Their major competitor is Hereaus, Engelhard, Hannovia. I'm quite sure that their gold lusters are totally comparable.
I don't think there is much competition in the marketplace these days. I tracked down Englehard bright gold and got Ferro's bright gold. On the MSDS it said DegussaMetalsCatalystsCerdec. So who is making what? The stuff I ordered works the same but sure doesn't smell the same...not that I want to smell it!
Kevin
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Post by Bert Weiss »

Kevin Midgley wrote:
Bert Weiss wrote:Geri

I'm not positive, but I think that Ferro's gold luster line is from their division that was originally Deguza and is made in Germany. Their major competitor is Hereaus, Engelhard, Hannovia. I'm quite sure that their gold lusters are totally comparable.
I don't think there is much competition in the marketplace these days. I tracked down Englehard bright gold and got Ferro's bright gold. On the MSDS it said DegussaMetalsCatalystsCerdec. So who is making what? The stuff I ordered works the same but sure doesn't smell the same...not that I want to smell it!
Kevin
Kevin

Did the MSDS comment on the food safe factor after the gold is applied and fired in?

I'm sorry that when I was on Vancouver Island that I didn't get a chance to explore more of the Island and visit more warm glassies. I was time and transportation challenged LOL.

A friend of mine in Maine mentioned that she went to hear a musician perform named Kevin Midgley. He has a CD out. I tuned right in as I don't think your name is that common.
Bert

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