What’s “Blue and White” pottery and it’s history


“Blue and white pottery” are called “Sometsuke” in Japanese. Pottery and porcelain are decorated under the glaze with a blue pigment, generally cobalt oxide.

The following gallery shows my recent “Sometuke” works.

What is the “Gosu”

The cobalt pigment is one if of the very few that can withstand the highest firing temperatures that are required. Historically, many other colors required over glaze decoration and then a second firing at a lower temperature to fix it. This painting method is called “Uwaetsuke” (Over glaze painting)

History

The origin of this decorative style was imported from China.  White Chinese  stoneware with their own glazed, white pottery and added decorative motifs in blue glazes.

Blue and white decoration first became widely used in Chinese porcelain the 14th century.

Blue and white ware making is appearance in Japan.   Where it was known as sometsuke. Various forms and decorations were highly influenced by China, but later developed its own forms and styles.

Gosu and how to use of it

A variety of the “Gosu” are available from pottery supplier.  Blue, Black and also various colors of the gosu  is available.  Some of them are come as powder or paste.

In kyoto (Kiyomizu Yaki), a gosu is crushed by the grinding ball mill for a month.

How to use the gosu:                                                                                                              Use the gosu with tapped water or green tea.   Some pro pottery painter prefer using green tea over the water. If green tea is used, make sure that all tea waste are removed.

Green tea contains “tannin” component. This main green tea component will combine with cobalt oxide and become tannin oxide. The tannin oxide will work as adhesive.

How to mix own “Gosu” -Formulation example

Here’s formulation example:

  •  Cobalt oxide    20
  • Nickel oxide    10
  • Manganese dioxide 10
  • Kaolin 50

Please use as reference only and be careful to make at your own risk. The final results are not guaranteed. 

How to practice “Sometuke”  YouTube

 

How to improve your “Sometsuke” techniques

  • Use quality paint brush, need high quality fine point brush for line drawing (Known as “Kotsugaki”) and “Dami ” brush–a fat brush to paint wide area.
  • Grind gosu well with a mortar and pestle
  • Decorate a lot of works–More you do, become better

Pottery Necklace Gallarey | Self-made only-one gift for your better half


Necklace made with a cray

As I shown on the YouTube video, we made a necklace with the pottery cray.
If necklace parts are made with pottery cray, that will cause for the stiff neck for the person who ware it.
Therefore, the cray balls should be made as lighter as possible as its could. A dye was made with small toy rubber balls with using the plaster. In this way, we can make the necklace ball of the cavity.

With this method, we can make wall as thinner as few millimeters. After making a thin cray slab and use the dye to make hollow balls. Three sizes of the cray ball were made.
After the fire, the final necklace assembly were done by my pottery class mate Yokko-san.

Final necklace work after the fire

With this method, we can make wall as thinner as few millimeters. After making a thin cray slab and use the dye to make hollow balls. Three sizes of the cray ball were made.
After the fire, the final necklace assembly were done by my pottery class mate Yokko-san.

Three balls are used with this necklace. “Seiji” blue, “Kuro-tenmoku” black glaze, and “Nyuhaku” a milky white glaze
The black ball in the center has many holes on it. I remove a lot of cray by the drill bit to further reduce the weight.

Final necklace works Gallery after the fire

Hints on the fire

Glaze was applied on the entire parts which creates a problem on how to fire. They can’t fire on the kiln shelves.

An ordinarily metal wire will melt down with the high-temperature of 1300 degree in centigrade. Thus, a special kiln wire must be use. A high-temperature resistance wire is sold in pottery shop. It is not too expensive. In Japan, about 30cm length of the wire is sold under 5oo yen (about 4 U.S. dollar).

I suggest that three “tsuku” is used to bridge and support the weight so that the wire does not bent by the heat.

Also, you’d better off coat the wire with alumina, this will enable you to remove the part from the wire easily even if it would be attached to the wire by melting glaze.

Summary

The technical part of how to make a plaster dye and cray balls are not explained in this article.

Please watch my YouTube video. Access to YouTube Make a Pottery Neckless

Good Luck!