Below is my favorite vase made by Sarah Gregory, a ceramicist in Berkeley, California. It's not the vase I bought from her 4 years ago which I also love and is smaller and not as detailed but was more affordable. This color palette though of pink and green is so very very lovely, and if I hadn't splurged on so many classes and workshops in this month of my birthday, I would've bought it for the $230 price. Yesterday I was fortunate enough to attend a workshop in her upstairs studio at the Berkeley Pottery Guild, where I learned that this pink is a mixture of Amaco bright red and white underglazes.
Ceramic lovers are equally attracted to the deeper hues of her vases.
Everything in Sarah's studio is gorgeous, even the test tiles. And I love how every tool she uses is visible and provides a glimpse into her process. Sarah told us not to believe anything she said, but to first test, test, test it yourself. Materials that she uses include a personal palette of underglazes: Duncan EZ Strokes and Amaco velvets for translucent color, Leslie Ceramics premixed underglazes for more opaque color. She mixes her own colors with Leslie's underglaze base and Mason stain. She warns that there are colors that will work with any clear glaze and temperature but you MUST test them.
Some of the shapes of her template echo the female form, and quite a few of her vases made me think of Venus of Willendorf. Sarah is very visual and very keen on testing, testing, testing.
She created these examples to show her students.
My friend, Meral really enjoyed Sarah's demonstration of slab building vases. Below you see Sarah shaping the halves after she just scored the sides. Sarah uses Standard cone 5 porcelain made by Michael Haney at East Bay Clay. She claims it is water-tight at cone 5 and is the best handbuilding cone 5 porcelain she has ever used. However, Sarah has also constructed vases from Bmix with grog, especially the taller and bigger vases.
For tools, Sarah uses
cheap and abuseable bristle fan brushes, numbers 4 and 6 and sumi
brushes, number 2 as well as small detail brushes from big box stores
like Michael's or Joann. She outlines before she fills in with more
underglaze her illustrations with an underglaze pen comprised of a
plastic applicator bottle, filled to between 1/4 and 3/4 full with a .3
mm extra fine metal tip sealed when not in use with thin floral wire, 30
gauge. The extra fine short tip is from Axner--search
the item TMTIP, tip size extra fine. Aftosa and Joann have tips
starting at .5mm. Also important are an xacto knife, work support in
the form of a plastic covered pillow form with a towel over it, awesome
task lighting (she has a skylight), high magnification reading glasses, a comfortable and
adjustable chair, a spray bottle, 150 or 200 mesh sieve, plastic mixing
cups, plastic storage cups (the coin top caps from Tap plastic are her
fave) and feet support.
Here are her steps for handbuilding a vase:
- make a template
- roll slab and place on mats made of plaster board rather than canvas for a smoother surface
- cut shape
- work edges and score
- stand and use rib to shape
- join pieces
- clean joints and add a bead of clay when needed (Sarah uses a small handheld extruder from Joann's)
- add bottom, which is thicker and a bit drier than the vase body
- compress seams
- create a foot (by cutting a tiny bit outside of the outline in order to have a bit of edge from the rest of the vase)
Sarah doesn't use extra slip but works with her clay when it's rather soft--she created the slabs in the demo the previous night, of course covered in plastic. I would describe the texture as pretty soft to the point of just about to become leather hard She then uses water to create slip on the scored edges before joining the two halves.
Lots of compressing the ends at the top of the vase.
Tips for Successful Handbuilding
- the various parts should have the same moisture content, the wetter the better
- try and use as little water as possible and wipe off excess slip
- reinforce problematic seams with a bead of clay made from that extruder
- compress all accessible seams and joints
- for cracks on leather hard pieces or greenware, compress or soak with a thin mixture of paperclay (she makes from shredded toilet paper and a thin slip of the clay she is using) and then compress
- for cracks on bisque, scrape away the clay around the crack until you get to the bottom of it; her experience has shown that if she only fills the crack (with paperclay or other mender) it will persist and get worse
- dry slowly and evenly
- remember to cut your nails before starting
Then we got to the demo on what Sarah does for surface decoration. Her underglaze pen is a combination of black underglaze and wax resist--she uses 037 Black Duncan EZ Stroke underglaze mixed with Aftosa green wax for cone 5 work. The mixture is not an exact science. She uses as little wax as possible to create a resist. A 1:1 ratio is a good place to start. For a strong line, she recommends using an underglaze that is heavily pigmented, and she adds just enough wax to the black underglaze to create a resist (again 1 part underglaze to 1 part wax is a good place to start). For the base color within the lines of the wax resist drawing, she adds water and vegetable glycerin--for thinner applications and to extend drying.
One of the reasons I love Sarah's pots so much is the feel of the overglaze under my fingertips. Here is Sarah's Cone 5 Transparent Satin Matte Recipe:
25.7 Wollastonite
34.3 Frit3124
33.3 Epk
6.7 Silica
She mixes her overglaze for dipping and applies it quite thin. Her overglaze has a relatively tough surface when fired and goes over great over underglazes (that have been bisqued). This glaze can be made more matte by lowering the silica 1 percent at a time and more glossy by raising the silica 1 percent at a time. Sarah's satin matte works best at cone 5, but will fire more glossy at cone 6.
In her demo of base color, she uses one layer of color (1.5 to 2 even coats). She says she adjusts the underglaze to suit the application with additions of water and vegetable glycerine and uses a fan brush for that background color. She also showed us her color transition backgrounds.
After we applied background color to some scrap porcelain tile, we practiced using our underglaze pens. I was using my friend, Meral's art book titled French Modern as reference for my drawings.
When using the underglaze pen, fill to between 1/4 to 3/4 of the bottle. We tried learning to control the pressure, to clear back pressure and avoid blobs to start--a paper towel is handy for clearing the blobs from your pen. Sarah gave us suggestions of drawing at a low angle, of trying not to push material into the tip, of letting the wax set up or hold the piece accordingly, and troubleshooting the pen. We learned that the wax will lose resistance over time or if left in the sun. Covering with plastic helps. When filling in with color, allow for thick and thin and let the color pool. You can fill with light over dark and dark over light. With a second background color, there's possible pinholing leaving a lining of the first color. Sarah also showed how she shadows and highlights, using darker shades for shadows by adding some of the original color. She adds a bit of the color's opposite in the deepest part of a shadow or on a turning edge. For highlights and lighter shades, mix a bit of the color and white; for a spot of highlight, add pure white on top of that.
My friend Meral's tiles...prolific and beautiful.
I was so impressed by the brushwork of my classmates. I ended up leaving one of my tiles blank and am holding off using my new underglaze pen until I decide on an image upon my amethyst background colored tile and after I've practiced drawing it. So much fun and so much learning!
