How Do Underglaze Colors Change in Oxidation vs Reduction? We Made 500+ Test Plates! | Fukaumi Shouten
When buying pottery materials online, what is your biggest concern?
We believe it's the anxiety of: "Will it really turn out the exact same color as the sample when fired in my own kiln?"
In the Fukaumi Shouten online store, we have primarily displayed sample plates of Gosu (blue underglaze) and colored underglazes fired on "Porcelain clay (Amakusa Pottery Stone) with Reduction Firing (gas kilns, etc.)." This is because it is the most standard condition used by professional Arita ware potters.
However, recently, we have been facing a "dilemma."
And now, despite some slight anxieties, we have made the decision to newly create over 500 "Condition-Specific Test Plates" and publish all of them on our online store.
Why did we go through such immense effort? Let us share the story behind the scenes.
To Prevent the Tragedy of "The Color is Completely Different"
Through our online store, we now receive orders from various professional potters and hobbyists all over the world.
In doing so, we noticed something.
Many of our customers use "Stoneware / Earthenware" instead of porcelain, and fire in "Oxidation (electric kilns)" instead of reduction firing.
And surprisingly, the fact that "if the clay or firing method changes, the color of Gosu and underglazes will be completely different" is not widely known.
A tragedy occurs when a customer sees a vivid blue sample plate fired on porcelain in reduction, buys it, and then fires it in their own oxidation kiln on stoneware—only to find the color turns dull or blackish.
This happens because we were only showing "samples for porcelain & reduction firing."
"If we leave it like this, we are not being honest and sincere with our customers."
Feeling this strongly was the starting point of this massive project.
The Reality of Color Change Taught by 500 Test Plates
To allow customers to check the finish close to their own environment (clay, glaze, firing method) in advance, we conducted tests with every possible variation we could think of.
[Variations of Test Plates Created This Time]
- Amakusa Pottery Stone (87 types) x Fukaumi Limestone Glaze / Reduction Firing 1280°C (2336°F)
- Amakusa Pottery Stone (87 types) x Fukaumi Limestone Glaze / Oxidation Firing 1230°C (2246°F)
- Seto Pottery Stone (60 types) x Maruishi Limestone Glaze / Reduction Firing 1280°C
- Standard Filtered Stoneware Clay (30 types) x Nihon Toryo No.3 Glaze / Reduction Firing 1280°C
- Standard Filtered Stoneware Clay (30 types) x Nihon Toryo No.3 Glaze / Oxidation Firing 1230°C
- Specially Filtered Stoneware Clay (30 types) x Nihon Toryo No.3 Glaze / Reduction Firing 1280°C
- Specially Filtered Stoneware Clay (30 types) x Nihon Toryo No.3 Glaze / Oxidation Firing 1230°C
- White Shigaraki Clay (30 types) x Nihon Toryo No.3 Glaze / Reduction Firing 1280°C
- White Shigaraki Clay (30 types) x Nihon Toryo No.3 Glaze / Oxidation Firing 1230°C
- *Plus 87 types of Arita Izumiyama Pottery Stone, etc.
The result: The colors changed far more than we imagined.
To be completely honest, a slight fear crossed our minds:
"If people find out the colors turn out this dark (or muted) in oxidation, they might stop buying, and our sales might drop..." (laughs).
However, rather than having you disappointed after receiving the product, we want you to choose after understanding, "Ah, it will be this muted color in my environment."
We wanted to prioritize that "Honesty," so we decided to hide nothing and publish everything on each product page of our online store.
Learning from Ko-Imari: A Touch of Dedication to Patterns
We thought it would be boring to just paint solid colors for these test plates. So, with the cooperation of a kiln in Arita, we hand-painted patterns referencing "Antique Ceramics (Ko-Imari / Antique Arita ware)".
Rather than just being simple color samples, we would be overjoyed if they could help stimulate your "Creativity" in ceramic expression, showing you, "I can express such lines and shading using this pigment."
Summary: Find the Best Color for Your Kiln
Even with the exact same pigment, if the clay changes and the fire changes, it will show you a completely different scenery.
That is by no means a "failure," but rather the profound depth and joy of pottery.
Currently, you can view these diverse sample photos on each product page in the Fukaumi Shouten online store.
Please compare them with your own "Clay" and "Kiln" conditions, and find the color that suits you best with peace of mind.
Find "Your Color" from over 500 Samples
From reduction to oxidation, from porcelain to stoneware.
Honest color samples assuming various environments are now available on each product page.
この記事の執筆者
佐賀県有田町出身。深海家13 代目。株式会社深海商店後継者。先祖は有田焼始祖の一人である百婆仙。熊本大学理学部理学科卒業後、東京の大手経営コンサルティング会社にて勤務。2021年8月に有田町にUターンし、有田焼及び肥前窯業圏の再興を使命に東奔西走する。