{"product_id":"siena-natural-3","title":"Natural Sienna","description":"\u003cb\u003eColor:\u003c\/b\u003e Natural Sienna\u003cbr\u003e\u003cb\u003eLightfastness:\u003c\/b\u003e AA\u003cbr\u003e\u003cb\u003eOpacity:\u003c\/b\u003e Opaque\u003cbr\u003e\u003cb\u003ePigment:\u003c\/b\u003e PY42, PR101, PBk7\u003cbr\u003e\u003cb\u003ePigment description:\u003c\/b\u003e Synthetic Iron Oxide, Synthetic Red Iron Oxide, Nearly Pure Amorphous Carbon\u003cbr\u003e\u003cb\u003eASTM Lightfastness classification:\u003c\/b\u003e I\u003cbr\u003e\u003cb\u003ePigment classification:\u003c\/b\u003e Mixture\u003cbr\u003e\u003cb\u003eColor Index Number:\u003c\/b\u003e -\u003cbr\u003e\u003cb\u003eViscosity range (mPa.s):\u003c\/b\u003e 15,000 - 20,000\u003cbr\u003e\u003cbr\u003e\u003cb\u003eColor Index\u003c\/b\u003e\u003cbr\u003eThe pigments used are both inorganic and organic. The inorganic ones have been used since antiquity and the vast majority come from or are extracted from minerals and clays, such as natural earths, siennas, and ochres. Titanium pigments, carbon, ultramarine blue, cobalts and cadmiums also belong to this category. Many of them are currently synthesised in industrial processes. Organic pigments are more modern; they were developed at the beginning of the 20th century thanks to the new synthesis methods in Organic Chemistry. These synthetic pigments are now a very important group in the manufacture of colours for artists, producing bright and luminous shades with extraordinary intensity and excellent stability and permanence. The range of organic pigments is currently very extensive and includes azo pigments, blues, phthalocyanine greens, dioxazines, pyrroles, anthraquinones, quinacridones, etc.","brand":"Vallejo Colors","offers":[{"title":"Default Title","offer_id":64141517390154,"sku":"22019","price":0.0,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0999\/0963\/2330\/files\/vallejo-studio-acrylic-200ml-19.jpg?v=1793260681","url":"https:\/\/vallejocolors.com\/en\/products\/siena-natural-3","provider":"Vallejo Colors","version":"1.0","type":"link"}