PLEASE ALLOW ME TO INTRODUCE MYSELF,

I’M A MAN OF CLAY AND GLAZE

PUSHED MUD AROUND FOR SEVENTY YEARS

OR TWENTY FIVE THOUSAND DAYS.

Robin Hopper is a man of many parts, mostly worn out, rusty or dysfunctional, due to a lifetime of excesses! He started working with clay at the age of three and is still doing it over 70 years later. His lengthy, peripatetic career as a mudpusher has included side trips into working as a Professional Actor, Stage Designer, Property Maker, Stage Manager, Stage Carpenter, Grocer, Greengrocer, Jazz Musician, Teapot, Wine and Beer-Bottle, Trumpet, Trombone and Bugle Player, European Travel Guide, Founder of Several Clay/Art/Craft Organizations, Alchemist, Geologist, Primatologist, Linguist, Ornithologist, Botanist, Ceramic Historian, Educator, Author, Garden Designer, Lecturer on Japanese Garden Design, Laborer and Star of Stage, Screen and Potter’s Wheel!

Monday, March 12, 2012

MATERIALS MAN: PART 8: MANGANESE + NICKEL

MONDAY, 12TH MARCH


TODAY'S POST IS BROUGHT TO YOU COURTESY OF:
MANGANESE AND NICKEL


PLEASE EXCUSE THE FUZZY IMAGES - I'M HAVING A LITTLE TROUBLE WITH THE SIZING ON THIS ONE. AT LEAST YOU WILL GET THE IDEA.


ALTHOUGH THEY EACH HAVE A RANGE OF POSSIBLE COLORS, MANGANESE AND NICKEL ARE BOTH PRIMARILY USED AS COLOR MODIFIERS TO GIVE MORE SUBTLETY, DARKENING OR SOFTENING, TO OTHER COLORANTS.



MANGANESE COMPOUNDS

MANGANESE COMPOUNDS ARE STRONGLY FLUXING COLORANTS, USED TO DEVELOP PURPLE IN BARIUM FLUXED GLAZES AND LOW-TEMPERATURE ALKALINE GLAZES, AND BROWN IN LEAD BASED GLAZES. IN HIGH-TEMPERATURE MAGNESIUM FLUXED GLAZES, FAWN, BEIGE AND PINK-BROWN MAY BE PRODUCED.  AT HIGH TEMPERATURES, USED ON ITS OWN AND EITHER  RUBBED INTO CLAY BODIES, OR PAINTED ON THEM, IT WILL FORM A MATT TO GLOSS, DARK BROWN TO PURPLE/BLACK SURFACE. MIXED WITH AN EQUAL AMOUNT OF COPPER, OR 2/3 TO 1/3 MANGANESE TO COPPER RATIO, IT CAN PRODUCE GOLD TO BRONZE IN OXIDATION OR REDUCTION FIRINGS AT CONE 6 - 10. THERE MAY BE SOME MICRO-CRYSTALLINE FORMATIONS. DO NOT USE ON DINNERWARE.  GRANULAR MANGANESE MAY BE USED IN CLAY BODIES, SLIPS AND GLAZES TO GIVES SPECKS OF COLOR THAT CAN FORM ATTRACTIVE BLEEDING INTO THE GLAZE.  HEAVY CONCENTRATIONS (OVER 4%) OF MANGANESE AS A COLORANT IN CLAY BODIES WILL LIKELY CAUSE BLOATING AND A LOW TOLERANCE TO OVER-FIRING, LEADING TO EARLY SLUMPING AND DEFORMATION OF PIECES. THIS PHENOMENON IS CALLED PYROPLASTIC DEFORMATION.         

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NICKEL COMPOUNDS

NICKEL COMPOUNDS ARE USED TO PRODUCE SUBDUED COLORS OF GREEN, GREY, BROWNS AND BLUES AND ALSO USED TO MODIFY OTHER, MORE INTENSE COLORANTS. IN HIGH-MAGNESIUM FLUXED GLAZES, ACID GREENS MAY BE DEVELOPED; IN HIGH BARIUM FLUXED GLAZES, PINK TO GRAPE PURPLE.  NICKEL IS OFTEN USED IN CONJUNCTION WITH ZINC CRYSTALLINE GLAZES WHERE IT GIVES A BLUE MATRIX AND PINK CRYSTALS.

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JUST TWO MORE POSTS ON THE THE MAIN COLORANTS TO COME. ON WEDNESDAY, MARCH 14TH, WE WILL LOOK AT RUTILE/TITANIUM. ON FRIDAY, MARCH 16TH,  IT WILL BE THE WILDLY COLORFUL AND SOMETIMES ERRATIC CHROMIUM 

SEE YOU THEN.
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