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!

Friday, March 16, 2012

MATERIALS MAN: PART 10: CHROMIUM



THIS POST IS BROUGHT TO YOU COURTESY OF CHROMIUM


CHROMIUM GENERALLY PRODUCES HEAVY, DARK GREEN, USUALLY OPAQUE COLORS. IN ELECTRIC-FIRED, LEAD-FLUXED GLAZES FIRED BELOW 950°C, CHROMIUM CAN GIVE A RANGE OF YELLOWS, ORANGES AND REDS. IN COMBINATION WITH TIN OXIDE IN OXIDIZING ATMOSPHERES CHROME--TIN PINKS THROUGH TO CRIMSON MAY BE ACHIEVED. IN GLAZES THAT CONTAIN ZINC, CHROMIUM WILL USUALLY TURN TAN THROUGH TO BROWN. IT CAN VOLATILIZE IN FIRING, EVEN AT LOW TEMPERATURES, COLORING ADJACENT PIECES PINK, PARTICULARLY THOSE HAVING GLAZES OPACIFIED WITH TIN, OR FLUXED WITH BARIUM. THE VOLATILIZED COLOR CAN ALSO  IMPREGNATE THE BRICKWORK OF THE KILN, RELEASING VOLATILE COLORANT INTO FUTURE FIRINGS. USED IN AMOUNTS OF OVER 5%, IT MAY CAUSE CRAWLING. CHROMIUM IS ALSO FOUND IN CHROMATE COMPOUNDS SUCH AS POTASSIUM DI-CHROMATE, LEAD CHROMATE, BARIUM CHROMATE AND IRON CHROMATE, WHERE IT HAS A SIMILAR, BUT MODIFIED EFFECT AS THAT EXPECTED FROM THE OXIDE OR DI-OXIDE FORM. WITH POTASSIUM ITS FLUXING POWER IS INCREASED, WITH LEAD, IT ALSO FLUXES MORE AND CREATES YELLOW ORANGE COLORS.  WITH BARIUM IT CREATES ACID YELLOW TO CHARTREUSE-GREEN. WITH IRON, IT CREATES YELLOWS IN OXIDATION AND BLUE-GREY TO BLUE IN REDUCTION.



CHROMIUM DIOXIDE IS THE ONLY COLORANT USED IN THESE TESTS.

_________________________________________________________________________________


THREE VESSELS FROM MY "SOUTHWEST SERIES"

METHOD OF PRODUCTION:  
PORCELAIN SPRAYED WITH TERRA SIGILLATA - BURNISHED AND THEN PAINTED WITH BLACK/BRONZE PIGMENT- FIRED TO CONE 9 IN OXIDATION - THEN TRAILED AND BRUSHED WITH CHROME RED LEAD GLAZE - THEN FIRED IN OXIDATION AT CONE 08 - CHROMIUM FUMING REACTION WITH TIN TO FORM GREY HAZE. I USE A HIGH WHITE LEAD FLUX CONTENT BECAUSE IT IS THE ONLY WAY THAT I CAN GET THE PRECISE SCARLET THAT I WANT FOR THIS WORK.

ALL FORMS OF LEAD ARE BASICALLY BANNED FROM USE IN EDUCATIONAL INSTITUTIONS AS THEY ARE TOXIC.  WHITE LEAD (LEAD CARBONATE),  RED LEAD (LEAD OXIDE) AND LEAD SULFIDE (GALENA) USED TO BE IN COMMON USE FOR GLAZES FOR DINNERWARE BUT ARE NOW NOT ALLOWED FOR USE IN NORTH AMERICA AMD MOST OF THE WESTERN WORLD. THE REASONS FOR ITS USE ARE THAT IT MELTS AT A LOW TEMPERATURE WITH A FAULT FREE COATING EXCEPT WHEN REDUCED.  MANY DESIRABLE COLORS NEED LEAD TO DEVELOP.  IF YOU WISH TO USE LEAD IN YOUR GLAZES, MAKE SURE THAT YOU DON'T USE IT FOR FUNCTIONAL WARE OR ON ANYTHING THAT MIGHT BE USED FOR STORING ACIDIC LIQUIDS IN. FOR TILES, SCULPTURE AND NON FUNCTIONAL USE IT MAY BE USED WITH CARE.  READ AVAILABLE LITERATURE AND KNOW WHAT YOU ARE DOING BEFORE MAKING OR USING LEAD FLUXED GLAZES.
 IF IN DOUBT, LEAVE IT OUT!



VASE - CLASSICAL FORM - HEIGHT 18"


TRIFOOT PLATE - 17" DIAMETER


OLLA FORM - HEIGHT 10" 


GLAZE PAINTINGS

THESE GLAZE PAINTINGS UTILIZE A HIGH-TECH SHEET MATERIAL NAMED PORCELAIN CANVAS SUBSTRATES (PCS) TO PAINT ON WITH GLAZES. GLAZES MAY BE USED AT ANY TEMPERATURE UP TO CONE 10. AND FIRED MANY TIMES IN DIFFERENT KILN TYPES. THE SUPER-THIN PORCELAIN-LIKE SHEETS. THE MATERIAL IS MADE FROM 96% ALUMINA. ORIGINALLY DEVELOPED FOR SPACE TRAVEL HEAT SHIELDS AND COMPUTER CARDS, IT IS A REVOLUTIONARY MATERIAL FOR THE CERAMIC ARTIST WITH DRAWING, PAINTING  AND GRAPHIC SKILLS.

I AM AWARE THAT THIS MATERIAL WILL BE TOTALLY NEW TO MANY OF MY READERS, SO NEXT MONDAY AND WEDNESDAY (MARCH 19TH + 21)  POSTINGS WILL BE ENTIRELY BASED ON THE MATERIAL AND ITS USE. I HAVE BEEN RESEARCHING ITS USES FOR THE LAST THREE YEARS


PCS GLAZE PAINTING:  "PRUNUS PERSICA"


PCS GLAZE PAINTING:  "SOUTHWEST SERIES #2



PCS GLAZE PAINTING:  "CALENDULA"

TERRA SIGILLATA GROUND FIRED TO CONE 8 IN OXIDATION,  FOLLOWED BY WITH CHROME RED AND CHROME YELLOW GLAZE DRAWING MADE WITH A GLAZE TRAILER AND FIRED TO CONE O8 IN OXIDATION

_______________________________________________________________________________




No comments:

Post a Comment