This is the third post focused on focused on my new glazes and work. Read part 1 and part 2, too.

When I try a published glaze I experiment on different clay bodies, and in different areas of the kiln. I then refine the recipe over the course of many firings until satisfied. The same, of course, goes for my own glaze creations, though mine are more experimental and may never, ever, turn out. I’ll write more about experimentation in a later post… I’m covering my glazing process for now.

I spray glazes over each other to varying degrees and thicknesses to obtain more color variation. Sometimes this is beautiful- sometimes hideous. Clay body, firing temperature, glaze thickness, reduction schedule (the temperature at onset of reduction, strength and length of reduction), and local material variations all affect glaze color.

Glaze thickness has a huge effect on color. Too thin and the glaze doesn’t develop good color, too thick and it can run or be a poor color. The same glaze needs to be thin on porcelain, slightly thicker on white stoneware, and thicker still on brown stoneware to develop the desired color. Some glazes are beautiful on porcelain, and terrible on brown stoneware.

Clay shrinks when fired. Bad glaze “fit” (making sure the glaze shrinks at the same rate and overall shrinkage as the clay) for a given clay body can cause crazing, crawling, or shivering. One must consider physics and thermodynamics in addition to coloration and texture.

Any glazes with rutile as a component are more prone to pinholing as a glaze defect. We have had entire kilns of our work go straight to the dumpster when these defects crop up. In the early 90s when I was trying to perfect a rutile blue we fired twice a week and went months without a success. Perhaps it’s contempt, but I’m no longer excited about rutile blue.

Now I fire a glaze firing every 2 or 3 weeks, and try to do some glaze tests in each. We are constantly learning and adding to our color palette. The somewhat frustrating and humbling part of being a potter is that once you give a piece up to the fire, anything can happen.

Right now I’m working on a custom set of dinnerware for a client with my sprayed glazing (see us unload it at 5 minutes, 57 seconds in to episode 3 of the Kiln Room). The dinner and lunch plates and large salad bowl are perfect. The pasta bowls and cereal bowls have pinholing on 60% of the pieces. Three bowls were fired on the same shelf – two of the three are pinholed. One is flawless. Why?

I really have no clue at the moment why this happened, but yesterday I threw ten more pasta bowls and 16 more cereal bowls to meet the order. You’d think after 40+ years I’d have this figured out, but it just doesn’t work that way.

We were at a 60th birthday party for a potter friend of ours a couple months ago with 6 potters with 35+ years experience each. We had this very discussion of how the kiln will throw you a curve every time you think you have the process down pat.

After all these years I still have only a tiny piece of the puzzle worked out.

This is the second post in a series focused on Michael’s striking new work. Read the first post here.

For the glossy blue and red glazes Michael starts with a clear glaze formula and adds colorants (metallic oxides). For dark blue, cobalt oxide; for light blue, a combination of rutile (rutile is titanium with iron impurities), cobalt carbonate, and red iron oxide. For red, copper carbonate, tin oxide, and a small amount of red iron oxide.

The matt blue is a low temperature copper blue glaze Michael modified for high fire. The yellow glaze uses yellow iron oxide as the colorant. Each glaze is in a different base. All glazes require extensive and continuous testing, and most glazes from books or articles haven’t worked as expected and need adjustment.

Michael designed and fabricated the kiln around his firing technique, which is tailored to our clay and glazes.

Welcome back! This episode of the Kiln Room finds us opening a completely cooled (this is rare for us!) firing. In this firing we have a lot of Peggy’s wax resist, and most came out exquisitely; a large custom ordered vase (with elephants); and a special dinnerware set that humbles and reminds us that experience provides some, but nowhere close to all, answers.

See more episodes of the Kiln Room…

This is the first post in a series of Michael’s striking new work. He has focused on colors matched with shapes intended to catch the eye. Many of these colors are unique and extremely difficult to reproduce in high fire ceramics.

Michael’s glazes are the result of over 40 years of research and experimentation. Thousands and thousands of firings, tests, failures and successes along the way have resulted in this style and presentation.

Try clicking the photos for full resolution images. Zoom in to see detail.

This is the first episode from our kiln room, shot Sunday morning, May 23rd. We had a lot of fun doing this and look forward to doing more. Maybe we’ll make a show of it!

In this first image, top right, the kiln is partly loaded and I’m building the setting to hold the various sized pieces for this firing. The way the kiln is stacked – how tightly and whether the shelves are staggered – all affect how the kiln will fire. Air flow, heat distribution, oxidation, reduction, intake, exhaust, gas and chemical reactions, shrinkage, timing between changes… It is always slightly different with so many variables. Just firing a kiln is an art and science.

In the second and third photos the kiln is fully loaded. It’s 1pm and I’ve lit the burners.

The 4th shot, at right, is of the kiln ~12 hrs into the firing at 1am. The peephole plugs are out to show the effect of reduction on the kiln. The intensity and color of the flame is an indicator of the strength of the reduction. This firing took 13.5 hours to reach 2350f.

The final photo was 36 hours later, after the kiln had cooled to ~250f.

Until the temp is below 400f we barely open the door…

The finished pieces go through quartz inversion at ~400f – a time of rapid shrinkage when they will easily crack. One can hear ting ting ting through the cracked door. In high fired stoneware and porcelin, there is approximately 13% shrinkage – about 10% of this happens during the glaze fire – torturing the pieces. A true trial by fire.

click any image to enlarge

After a lot of refining and studious work, I finished several unique new glazes this month. With them, I have been throwing porcelain instead of the brown stoneware clay. I’m loving the way the new glazes are reacting with it! The colors are more vibrant than ever.

We’re at a high point in experimentation success and expression.

As I write, Peggy is in her studio filling color in on pieces she wax decorated over the past few days. I’ve been making a lot of new pieces in preparation for our expansion in Studios on the Park.

The photo above is of two slab vessels I carved with geometric intertwinning imagery, along with new wheel thrown porcelin teapots, and a large porcelain covered jar.

The photo below is a group of bisque fired porcelain bottles and vessels waiting to be glazed. Tomorrow is glaze day and I plan to finish some of them. I am developing more new glazes for the porcelain and revisiting some of the combinations I loved in my past porcelain work.

Title: Butterfly Woman
Spirit Figure wall piece. Design and glazing by Peggy Vrana.

Dimensions: 7″ x 16 1/2″

Turtle

Dragonfly

Title: Turtle and Dragonfly
This small round vase holds the designs most preferred by Peggy in her geometric repertoire. One side is a turtle and the other side is a dragonfly. The turtle symbolizes mother earth, female fertility, and long life. The dragonfly symbolizes transformation.

Dimensions: 6″ x 8 3/4″

Peggy’s collaboration with D’Ambino Winery and Cellars, a winery owned and operated by a family of talented and fun loving musician/winemakers, has shaped and inspired her to make pieces with music as a central theme.

Like the D’Ambinos, we’re a family of music lovers, too. Many years ago – way before MySpace, color computer monitors, and almost before the Internet was invented – we were in the band Up in the Air. Peggy played flute and Michael played conga drums. It was great fun and we still have our original instruments decorating our home.

Peggy has always enjoyed illustrating and glazing people in her wax-resist work. It’s a natural next step and adventure to capture musical life, and she is eagerly exploring and inspired to do more musical designs.

The photo of the hanging plate above is the 3rd piece capturing musical life. It’s not for sale – we’re keeping it. The first two, including “D’Ambino Family at Play,” were sold during the Art of Wine auction on April 16th, 2010.