Ceramic Materials

Logged in as Logout

•The secret to cool bodies and glazes is alot of testing.
•The secret to know what to test is material and chemistry knowledge.
•The secret to learning from testing is documentation.
•The place to test, do the chemistry and document is an account at SECUREURL.
•The place to get the knowledge is http://digitalfire.com

Sign-up at SECUREURL today.

Copper Carbonate

Formula: CuCO3
Alternate Names: Synthetic Malachite, CuCO3

Oxide Weight79.54
Formula Weight123.55
Enter the formula and formula weight directly into the Insight MDT dialog (since it records materials as formulas).
Enter the analysis into an Insight recipe and enter the LOI using Override Calculated LOI (in the Calc menu). It will calculate the formula.
DENS - Density (Specific Gravity) 3.70
GSPT - Softening Point 500C D
TGA - TGA See accompanying curve image

Conceptually, copper carbonate is CuCO3, however this form is not normally available in the market (copper carbonate basic is the article of commerce) so the powder should be viewed as a family of compounds.

This material is considered volatile during firing and thus can affect the color of other pieces in the firing. See Copper Carbonate Basic for more information.


Switching copper carbonate for copper oxide in a fluid glaze

The top samples are 10 gram balls melted down onto porcelain tiles at cone 6 (this is a high melt fluidity glaze). These balls demonstrate melt mobility and susceptibility to bubbling but also color (notice how washed out the color is for thin layers on the bottom two tiles). Both have the same chemistry but recipe 2 has been altered to improve slurry properties. Left: Original recipe with high feldspar, low clay (poor suspending) using 1.75% copper carbonate. Right: New recipe with low feldspar, higher clay (good suspending) using 1% copper oxide. The copper oxide recipe is not bubbling any less even though copper oxide does not gas. The bubbles must be coming from the kaolin.

Copper carbonate power.

Pure cobalt carbonate and copper carbonate at 1850F

Cobalt carbonate (top) and copper carbonate (bottom). Left is the raw powder plastic-formed into a sample (with 2% veegum). Right: fired to 1850F. The CuCO3 is quickly densifying over the past 100 degrees and should begin to melt soon. It is long past the fuming stage.

LOI profiles of more common glaze and body materials

These are pure samples (with 2% binder added) of (top left to bottom right) strontium carbonate, nepheline syenite, cobalt carbonate, manganese dioxide, bentonite (in bowl), 6 Tile kaolin, New Zealand kaolin and copper carbonate. I am firing them at 50F increments from 1500F and weighing to calculate loss on ignition for each. I want to find out at what temperature they are gassing (and potentially bubble-disrupting the glaze they are in or under). Notice how the copper is fuming and spitting black specks on the shelf, this happens right around 1500F. These stains on the shelf darkened considerably when the kiln was fired higher.

Copper carbonate fuming

And example of how copper carbonate fumes during firing. The white sample on the left was near the copper sample, at around 1500F the fumes discolored its facing edge. These are permanent, they do not fire out but get darker with increasing temperature (this is 1950F). The kiln shelf was also discolored outward about half an inch from the copper specimen.

2% Copper carbonate in two different cone 6 copper-blues

The top base glaze has just enough melt fluidity to produce a brilliant transparent (without colorant additions). However it does not have enough fluidity to pass the bubbles and heal over from the decomposition of this added copper carbonate! Why is lower glaze passing the bubbles? How can it melt better yet have 65% less boron? How can it not be crazing when the COE calculates to 7.7 (vs. 6.4)? First, it has 40% less Al2O3 and SiO2 (which normally stiffen the melt). Second, it has higher flux content that is more diversified (it adds two new ones: SrO, ZnO). That zinc is a key to why it is melting so well and why it starts melting later (enabling unimpeded gas escape until then). It also benefits from the mixed-oxide-effect, the diversity itself improves the melt. And the crazing? The ZnO obviously pushes the COE down disproportionately to its percentage.

1% and 2% copper carbonate in a cone 6 transparent

The recipe also contains 2.5% tin oxide. The clear base is the best we found to host the copper blue effect (this is actually one we recalculated to source the Al2O3 more from clay and less from feldspar to get much better slurry properties). Other base recipes are more fluid, blister more easily, the slurry does not work as well and they are not as blue. There is an Insight-live.com share to see the recipe and notes at http://insight-live.com/insight/share.php?show=ruY3muruhJ1

Almost final recipe for cone 6 copper blue - G2806B

This is the winner of a five-way cone 6 copper blue glaze comparison that started with my dissatisfaction with Panama blue. The porcelain body (of this mug) is the new Plainsman P300. When I compared these glazes I did not just eyeball them on a tile. I compared the bases first (without the copper and tin) using flow testing, slurry performance comparisons, ball melt tests to compare bubbles and color where very thick. Then I tried more copper and did more flow tests. I also did leaching tests. Where needed I adjusted recipes to increase clay content (while maintaining chemistry) so the slurries would work better. Without my account at insight-live.com to keep all of this organized it would have been so much more difficult, actually, I probably would not even have bothered with the project. The recipe is G3806C.

Out Bound Links

In Bound Links

By Tony Hansen

XML for Import into INSIGHT

<?xml version="1.0" encoding="UTF-8"?> <material name="Copper Carbonate" descrip="" searchkey="Synthetic Malachite, CuCO3" loi="0.00" casnumber="3444-14-2"> <oxides> <oxide symbol="CuO" name="Cupric Oxide" status="" percent="64.400" tolerance=""/> </oxides> <volatiles> <volatile symbol="CO2" name="Carbon Dioxide" percent="35.620" tolerance=""/> </volatiles> </material>

Feedback, Suggestions

Your email address


Your Name


Copyright 2003, 2008 http://digitalfire.com, All Rights Reserved