Old Chinese Gosu 2 underglaze (100g)

[Quality & Craftsmanship] For over half a century, blue and white porcelain (Sometsuke) and Somenishiki ware created using Fukaumi Shouten's Gosu (blue underglaze) have been beloved by royalty and aristocrats worldwide, and proudly exhibited in museums. Featured on the BBC and Japanese National Television Our profound history and traditional techniques caught the attention of the world when we were featured on the prestigious UK television series, BBC's "Great Japanese Railway Journeys". In Japan, artists utilizing our Gosu have been featured on prominent programs such as "Wafu Souhonke" and NHK's "Ippin," which highlight the nation's finest traditional craftsmanship. Our products are also trusted for official signage at research institutions and government agencies throughout Japan. We promise to deliver this world-recognized, authentic Arita Blue directly to your studio. [The Manufacturing Process] To maintain this exceptional quality, it takes more than a month from the start of production to completion for Fukaumi Shouten's Gosu. By combining Fukaumi Shouten's unique ingredient blend, our proprietary firing technique (Calcination), and the only stone-milling technology in Japan to micro-pulverize the grains, we achieve the ultimate underglaze. Through these rigorous processes, brushstrokes become incredibly smooth, and the Gosu is highly resistant to burning out, even at high concentrations. You will not need to hand-grind the pigment yourself once it arrives; it is ready to use. Fukaumi Shouten is the only historic Gosu manufacturer that sells its products directly online to individuals worldwide. That is why we can offer authentic, professional-grade quality directly from our factory. [The History of Gosu in Arita] The synthetic Gosu currently used throughout Japan was developed by the Fukaumi family during the early Meiji period (late 19th century). In 1870, the renowned German chemist Gottfried Wagener was invited to Arita. Dr. Wagener taught Heizaemon Fukaumi and his sons, Suminosuke and Takeji, the chemical method of producing the color blue using cobalt. Following this, the Fukaumi family conducted extensive research and successfully developed a scientific method for producing stable Gosu. As a result, vivid and reliable synthetic Gosu began to be widely used in Arita and across Japan, establishing the world-famous "Japan Blue". Please experience our premium Gosu, born from centuries of history, tradition, and the power of chemistry. [How to Use] Clay Type: Suitable for both Porcelain and Stoneware/Earthenware. Firing Method: Suitable for both Oxidation and Reduction firing. Optimal Firing Temperature: 1230°C – 1300°C (2246°F – 2372°F) [Firing Conditions for Sample Plates] The color samples shown in the main product images were fired under the following conditions: Clay Body: Amakusa Pottery Stone (Porcelain) (Composition: SiO2 72.04%, Al2O3 18.16%, Fe2O3 0.65%, TiO2 0.04%, CaO 0.49%, MgO 0.09%, Na2O 0.58%, K2O 3.00%, Ig.Loss 4.55%) Firing Temperature & Atmosphere: 1280°C (2336°F) / Reduction Firing *Note: The color of the underglaze will change depending on your clay body and whether you use oxidation or reduction firing. Please test in your own kiln. [Frequently Asked Questions] Q: How do I use the pigment? A: It arrives in a highly concentrated paste form. Please dilute it with water according to your purpose. For line drawing (outlining), a general guide is 1 part Gosu to 3 parts water. For Dami (washes), use 1 teaspoon of Gosu to 80ml-250ml of water. Please adjust to find your ideal shade. Q: Should I add a binder or adhesive (like gum arabic or CMC)? A: Our Gosu does not contain added binders to allow you flexibility. If the pigment is not adhering well to your bisque ware, or if your painting process requires touching the surface repeatedly, we recommend adding a small amount of your preferred binder. Q: How should I store it if I won't use it for a long time? A: We recommend storing it tightly sealed in the container. If it dries out, simply add water and grind it again in a mortar to return it to a paste. Q: What causes the pigment to crawl or repel during firing? A: Applying the pigment too thickly is the most common cause of crawling. It can also be caused by dust or oil (from hands) on the bisque ware before painting. [Shipping & Postage (International)] If you place your order before noon (JST), it will generally be shipped the next business day from our factory in Japan. *If your order includes made-to-order items like specific glazes, the entire order will be shipped once all items are ready. About Shipping Fees: Shipping costs are automatically calculated at checkout based on the total weight of your order and your delivery address (Country/Region). Available Shipping Methods: During checkout, you can choose the delivery method that best suits your needs. EMS (Express Mail Service): Fast and reliable with tracking, but shipping fees are higher. Typically arrives in 3 to 7 days depending on the destination. Surface Mail (Sea Mail): The most economical option with lower shipping fees, but delivery is slow. It typically takes 1 to 3 months to arrive. *Please note that customs duties or import taxes may apply upon arrival in your country, which are the responsibility of the buyer.