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  • 2 months later...

I applied this glaze  to a mid fire white clay body (Little Loafers) according to the directions. The result was a dull gray/black drab  at  cone 5. Very disappointed. I called Spectrum and they advised that I  put  up to 6 or 7 heavy coats on. I tried this a second time on a test bowl and fired to  cone 6  and got the same result as before. This is just a real crappy glaze in my opinion.

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Metallic Rain, which I have not tried, is similar in chemistry to Spectrum Metallic Mirror and Amaco Palladium.

 

Amaco says their leaded Palladium is not dinnerware safe, but Spectrum says leaded Metallic Mirror is food-safe based on the glassy non-leeching finish of the glaze  "Contains some heavy metals and/or cadmium compounds but passes test for lead and cadmium release.".

 

You need a small amount of lead to create this type of look.  But they don't use enough lead to make these glazes reliable.

 

 

I think you'd be far happier with a standard ^05 lead-manganese glaze like these sold by Clay Planet - very reliable, but not food safe.

 

http://shop.clay-planet.com/pint-722-aztec-gold.aspx

 

Has anyone tested Spectrum's new Metallic Gold Rain?  I would like to try it on a sculpture but need to pay shipping to test.  I assume it doesn't actually look like the promotional test tile- but I'm looking for something stunning!!

 

Thanks!!

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I have what I call a "Bronze" glaze, not quite the bright gold but it has it's own cachet. See the pot to my left in photo. Basic recipe is:-

Spodumene 38

Feldspar      58

Clay               4

Red Iron         3.5

That gives a gloss gold in reduction at C10 using K Spar and a satin using Neph Sy. Add 2 Co and 1 Cr to give the charcoal you also see on the pot in the photo. Tends to pinhole but a little more Si fixes that, unfortunately it also glosses the matt version.

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It could be that too much lead has evaporated from these ^6 glazes if you fire too slowly.

 

I found a ceramics journal from 1904 which quantifies the percentage of the lead in a glaze, fired in a sagger, which vaporized per hour.

 

Journal of the Society of Chemical Industry, Volume 23  - Society of Chemical Industry (Great Britain)  1904

http://books.google.com/books?id=lkLOAAAAMAAJ&pg=PA470&dq=kiln+firing+%22lead+glaze%22+loss+per+hour&hl=en&sa=X&ei=qhTnUpKpAYPvoASxlIGoCw&ved=0CDsQ6AEwAA#v=onepage&q=kiln%20firing%20%22lead%20glaze%22%20loss%20per%20hour&f=false

 

Without rereading it I think the volatilization of lead per hour at cone 6 was about 1/3 per hour.  At higher cones it's quickly gone.

 

These commercial glazes are partially lead fluxed manganese glazes which form a green, blue or red glass, with a reflective layer of gold or silver on the surface.  The key to success with these glazes seems to be having a very smooth bisque surface and a thick application that often runs.  The Amaco Palladium has a tendency to pinhole on many clays which I've only seen in fluorine containing frits like Ferro 5301 and 3269. 

 

I prefer the reliability of the ^05 gold glaze, which becomes especially gold when placed over a previously fired ^6 glaze to provide a smooth surface and protection against clay off-gassing.

 

I thought the golds would be out of it pretty low on the firing scale, after which you get the colors written above.

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  • 1 year later...
 

Good Afternoon, 

 

I would greatly appreciate your help with some glazing / kiln issues I am experiencing. Your help is so appreciated!! 

 

I recently purchased the potters choice Saturation Gold glaze and I fired in my electric kiln, the cone 5 did not bend at all.

I also had a self supporting cone 05 in the kiln and that bent only a little. 

clearly the kiln did not reach the temperature it was supposed to reach.. 

but I now have this issue, all the pieces that I glazed with the saturation gold are now black with a matte finish instead of gold. 

 

I am really disappointed and discouraged. 

 I then decided to re-fire on medium instead of going through the process of low then med then high for my three knobs. 

 

I believe the kiln is not getting hot enough? 

 

I apologize for being so detailed I just want to be sure to get the right diagnosis. 

 

when I start the kiln I go by the manual which says to turn each knob after each hour. 

There are three knobs. 

so I put the first knob on low for an hour, 

after the hour I turn the second knob on low for an hour, 

after the hour I then turn the third knob on low for an hour,

after the hour I now 

 

turn the first knob on medium for an hour, after that hour,

 I turn the second knob on medium for an hour, after that hour 

I turn the third knob on medium for an hour 

 

then the same goes for turning it on high

 

after each hour i go to the next knob and turn it to high

 

I apologize for being so detailed I just want to be sure to get the right diagnosis. 

 

Do you think I have done the right thing by refiring on medium ?  Is this okay?    do you think the glaze will come out now? or have I done the wrong thing? will it still be black? 

 

anyway to fix this? should I have reglazed it with the gold before firing again? 

 

I greatly appreciate all your help, it really means a lot!    I am working on a piece for my church and it was supposed to be gold and I now I am so upset that I cannot deliver. 

 

any advice is so appreciated 

 

thank you so very much for your kindness!!

 

Alice 

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  • 1 year later...
  • 3 years later...

One item of note is any metalic gold halo may not be suitable for drinking or eating from so maybe use it on the outside of a food container unless it says its fine for food on the jar. I doubt that very much as well.

oh wait heres the info on that glaze from tghe net-yep not so good for humans to eat from.Gotta love the heavy metals and this special warning as well (contemplating pregnancy.)??never seen that warning before.

 

Glaze in the Spectrum Cone 06/04 Low Fire Metallics Glaze Series. 

SHAKE AND STIR WELL:
Brush apply three flowing coats to cone 04/03 bisque. Let dry, and fire to cone 05.

(3) Not dinnerware safe. Lead-free, but contains other heavy metals that are leachable after firing. 

Caution: Product should be not be taken internally. Contains ingredients not suitable for ingestion or inhalation. 

Precautions:
Do NOT spray apply.
Wash hands immediately after use. When using, do not eat, drink, or smoke. Wear a work apron. Avoid using if pregnant or contemplating pregnancy. Keep out of reach of children. If swallowed, get prompt medical attention.

 

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I've contemplated pregnancy on several occasions, though I've decided against it each time.  I'm going to guess it has to do with prop 65 warnings?  Anything with lithium has to carry a warning for pregnant women, as well as a literal ton of other minerals and compounds.  Might be nicer to say that instead of "contains materials known to the state of California to cause birth defects"

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They have to say that because some things are more hazardous in the first trimester than later on, and a lot of people don't find out they're pregnant for the first 6 weeks or so. Growing another human can be kind of arcane. You're also not supposed to eat lunch meat or clean the cat box, or have more than one tuna fish sandwitch a week.

I find it funnier that they have to say not to eat the stuff. Y'think?!??

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