Potters & Sculptors - Making Rock from Mud
I have been a hobby potter for about 18 years. For 10 of those years I have been visually impaired. Making things didn’t suffer much when I lost my good sight, but glazing became a recurring nightmare. I tried brushing glaze and couldn’t tell how thick I was applying glaze or see brush marks in the glaze. Dipping pots is OK, but everything looks commercial if a pot is dunked in a single glaze and I cannot tell when I’ve missed a place when I glaze. Also, I like making big pots and it takes a lot of glaze and a strong arm to dip a big piece. So, I decided to give applying glaze with a sprayer.
I opened the kiln this morning to find out how my first attempt at glazing with a sprayer worked. Several lessons were learned, but first let me tell you about the process.
I bought a “Critter” sprayer, years ago, but never used it because I didn’t have a compressor. It was a classic case of putting the cart before the horse. Four months ago I ordered a Central Pneumatic compressor from Harbor Freight. I then put together a rudimentary spray booth out of a large cardboard box and a utility sink. The Critter is a siphon feed sprayer and has a fairly large pattern. Only the liquid tube is adjustable.
I had several dark clay pots (Highwater Clay’s Red Rock) and one pot made with Highwater’s Little Loafer. All had been bisque fired, and the white pot had some work with sgrafitto that I wasn’t happy with, so I put a bit of Archie Bray’s “sticks to anything” white slip on that pot with a rib to confuse the pattern of the sgrafitto and let that dry well. It did not fall off during either drying or firing.
I used 3 glazes, Bone from MC6, Variegated Slate Blue-Green (modified from MC6) and Sankey’s Iron Red. I also sprayed one small pot with Waterfall Brown and dipped the rim of one pot in Frasca Ash Glaze.
All of the pots but the one with Waterfall Brown were first sprayed with Strontium Crystal Magic (warm). The base of the large pot was sprayed with Bone, the middle with VSB – modified, and the top with Sankey’s Iron Red. Three small pots with some surface texture were sprayed with Bone on the base and VSB on the top. One pot was sprayed with VSB on the base and Sankey’s Iron Red on the top.
The firing schedule was,
Segment Ramp Temp Hold
1 100 220 0
2 350 2000 0
3 125 2185 30
4 9999 1900 0
5 125 1700 60
5 125 1400 0 (complete)
The kiln fired successfully in 14 hours and change.
Before discussing findings you should know a little about my visual impairment. I have little depth perception and depend on side lighting and shadow to illuminate texture and I have little perception of color. I cannot look through peep holes and see the cones during firing. So, I have to trust the digital timer and see whether the right cone fell.
Bone and VSB performed as expected. The Iron Red was an ugly brown. The Waterfall Brown was brown where thicker under the rim and in stamped texture on the base and was what my wife describes as “moss green” on the thinner areas. The Frasca Wood Ash did not melt and did not run. Furthermore it crawled in areas, especially on the white test tile.
I glazed the lower portions of pots first and got more overspray onto the top portion of the pots than I realized and glazes that were applied to the tops ran and did not cover well. Spray each glazed area and let dry before applying another.
Try another Iron Red glaze. Maybe “Reader’s Digest Red” or Randy’s red.
Should I fire to a higher temperature? The 6 cone bent. There seemed to be a good melt with everything but the wood ash. I need to read about Frasca Wood Ash glaze. Maybe it is a cone 10 glaze.
I had several test tiles in the firing. Zam Celadon looks great dipped or brushed. I really like the look where it was over black underglaze that had been sponged off leaving it in only depressed areas of texture. Try spraying ZC on textured pots.
Try another ash glaze. Maybe tweak the Frasca by adding flux? I was surprised that it is so dark and the little bit of cobalt that was added was not visible to me. The ash source is from the neighbor’s wood stove. I think it is all from hardwood, mostly red oak. I have about 15 pounds of sifted ash. I need to find something to do with it.