What does manganese dioxide do in a glaze? What color does manganese dioxide produce? What is manganese dioxide used for? What is manganese brick

MnO₂  

Manganese dioxide (MnO2) is an inorganic compound. It is a black to brown-colored material that occurs naturally as the mineral pyrolusite. In addition to water treatment, MnO2 has many uses. Manganese dioxide technology is one of the most commonly used and least understood applications.

Every tool in the toolbox has its designed use. This does not mean that a screwdriver does not become a chisel or a pipe wrench becomes a hammer. While this works, the screwdriver does bend and the pipe wrench does break. The true professional uses a hammer to drive nails and a chisel to remove excess material. Manganese dioxide catalyst is an important tool in the water professional’s toolbox. Understanding media mechanics and being competent with their application is the responsibility of the people working in the water industry. When we use the right tools for the job, we can leave the magic wand at home in the toy box.

Manganese Dioxide - Uses in Pottery

Manganese is used to stain clays (using black) and to impart fired speckling (as a decorative effect).

The applications include the use of MnO2 as an inorganic pigment in ceramics and in glassmaking. Manganese is a colorant used in bodies and glazes, producing blacks, browns, and purples. Smaller amounts are easily dissolved in most glaze melts, however, around the 5% threshold, the manganese will precipitate and crystallize. In large amounts in a glaze (i.e. 20%), metallic surfaces are likely.
In glazes below 1080°C, it can give coffee color browns when used with tin.

Above 1080C, half of the oxygen disassociates to produce MnO, a flux that immediately reacts with silica to produce violet colors in the absence of alumina, browns in its presence. Thus if it is being used in glazes fired below 1080C it should be considered as MnO2, if above it should be taken as 81.5 MnO and 18.5 LOI. In glazes it will behave in a refractory manner, stiffening the melt. Because to the expulsion of oxygen at 1080, glazes using manganese should avoid this temperature range to reduce the chance of blistering and ruining of the glaze surface. This material is available as a pure material or as a ground ore (pyrolusite). Thus while generically it is pure MnO2 the actual name-brand materials may only be 75% MnO2. Manganese dioxide is the key to Rockingham brown wares which are made by employing about 3% iron oxide and 7% manganese in a transparent lead glaze of a recipe such as: Feldspar 28, Kaolin 14, Flint 4, Lead bisilicate 40, Whiting 4.

Manganese browns have a different, often more pleasant character than iron browns. Mixed with copper oxide it gives metallic bronze. With small amounts of cobalt oxide, a deep violet can be obtained. Other interesting colour effects are obtained with copper in crystalline glazes (2-5%).

Formula: MnO₂
Molecular Weight: 86.9368 g/mol
Form: Brown to Black Powder and Chunks
CAS Number: 1313-13-9
Density: 5.03 g/cm³
Synonyms: Manganese dioxide, Manganese(IV) oxide, Pyrolusite, hyperoxide of manganese, black oxide of manganese, manganic oxide, Manganese peroxide