{"product_id":"prni-black-stoneware-clay","title":"PRNI Black Stoneware Clay","description":"\u003cp id=\"isPasted\"\u003eBlack stoneware clay with 40% impalpable grog 0-0.2 mm (up to 80 Mesh). Formulated for artistic ceramics, it is ideal for wheel-throwing and modelling smooth pieces with fine details. The high content of grog confers an excellent behaviour during drying and firing. It’s beautiful and intense black firing colour in oxidising atmosphere is very exclusive of PRN range and becomes an ideal artistic mean of expression. In reducing atmosphere, metallic effects with shades of blue are obtained. Suitable for tableware (\u003cstrong\u003efood-safe\u003c\/strong\u003e), according to ISO 6486. Available in extruded body (moist form).\u003c\/p\u003e\u003cp\u003eFiring range recommended for the clay to develop its best performance, both in terms of technical and safety characteristics, under conventional firing conditions. The colour samples may show temperatures outside the recommended range to provide a broader view, but these are pieces fired under controlled conditions. Cone equivalence according to Orton table for self-supporting cones, regular-SSB and 150ºC\/hr heating rate.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eRecommendations for use with glazes\u003cbr\u003e\u003c\/strong\u003eUse zinc-free (Zn-free) glazes to prevent from unexpected reactions such as bubbling or colour changes. Other elements that can react are zirconium (Zr) and tin (Sn). We recommend consulting your usual glaze supplier to ensure proper suitability with this ceramic clay body.\u003cbr\u003eDo not use glazes with a low coefficient of thermal expansion (a25-300°C \u0026lt;60x10-7°C -1). The PRN clay fired at high temperature has a high coefficient of thermal expansion in the range of 100 to 200°C, which causes tensions between the glaze and the support, mainly in pieces glazed on one side only, which can cause breakage during cooling in the kiln or even later (for example, when pouring hot water inside). Check with your usual glaze supplier to ensure that you use glazes with a medium-high coefficient of thermal expansion (a25-300°C \u0026gt;60x10-7°C -1).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eSpecifications:\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eFiring range: 1200-1240°C \/ Cone 5-6\u003c\/li\u003e\n\u003cli\u003eBiscuit temperature: 1000°C \/ Cone 06\u003c\/li\u003e\n\u003cli\u003eWater content: 21%\u003c\/li\u003e\n\u003cli\u003ePlasticity (IP Atterberg): 19\u003c\/li\u003e\n\u003cli\u003eCarbonate content (CaCO3): 0%\u003c\/li\u003e\n\u003cli\u003eDrying shrinkage: 8.2%\u003c\/li\u003e\n\u003cli\u003eFiring shrinkage 1240°C: 5.4%\u003c\/li\u003e\n\u003cli\u003ePorosity (water absorption) at 1240°C: 4%\u003c\/li\u003e\n\u003cli\u003eDry bending strength: 5.9 N\/mm2\u003c\/li\u003e\n\u003cli\u003eFired bending strength 1240°C: 51.4 N\/mm2\u003c\/li\u003e\n\u003cli\u003eThermal coefficient 1240°C (25-500°C): 63.8x10^-7°C ^-1\u003c\/li\u003e\n\u003cli\u003eFiring: Ceramic kiln high fire\u003c\/li\u003e\n\u003cli\u003eGrog: Impalpable grog\u003c\/li\u003e\n\u003cli\u003eState: Moist form (plastic body)\u003c\/li\u003e\n\u003cli\u003eStiffness: 4 throwing and modelling\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"COLLET","offers":[{"title":"12.5","offer_id":55424081199490,"sku":"P1705","price":17.26,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0865\/4399\/1066\/files\/PRNI-Black-Stoneware-Clay.jpg?v=1752679402","url":"https:\/\/potterycrafts.live\/products\/prni-black-stoneware-clay","provider":"Potterycrafts","version":"1.0","type":"link"}