METHOCEL cellulose ethers have been around for many years and are used in countless products. They can function as highly efficient thickeners, film formers, binders, water retention agents, suspension aids, hardeners, lubricants, protective colloids and emulsifiers.
Methocel binders are common in alumina refractories to give them dry strength. In glazes, they are used to provide many of the above qualities. They burn away so do not have an impact on the chemistry of the glaze, only its physical working properties.
Methocel products are soluble in cold water, but since the particles are so fine, they must be well dispersed in hot water or in a powder mix first. Different types vary in the temperature at which they become water soluble and problems with dispersion usually relate to incomplete wet-out of the individual particles when outer gelatinous membranes on aglomerations of particles shield the remainder from hydration. It is almost a must to have a good variable speed mixer to produce a good solution of these materials. In addition, the materials have a shelf life of three of four years.
To prepare a solution of Methocel, do one of the following:
-Heat approximately 1/3 of required volume of water to at least 194F (90C). Add the METHOCEL powder while, agitate until particles are thoroughly wetted and evenly dispersed. For complete solubilization, add remainder of water as cold or ice to lower temperature until water soluble temperature is reached. The powder then begins to hydrate and viscosity increases. Continue agitation for at least 30 minutes after the proper temperature is reached.
-Combine METHOCEL powder with other dry ingredients. For glazes 1/2% or less is usually suitable. Thoroughly blend the dry ingredients, then add the dry mix to the water and mix thoroughly until the mix is stable (this could take some time). The rate of hydration will depend on how well the particles of Methocel have been separated by the other dry ingredients.
These products are used in the food industry and so pose little danger from ingestion. Like flour dust, however, they can pose an explosion danger when poor hygenic practices results in heavy dust.
Contact Dow Chemical, Technical Service & Development, METHOCEL Cellulose Ethers, Larkin Laboratory, MIDLAND, MI 48674 for more information and the METHOCEL Cellulose Ethers Technical Handbook. For samples, call 1-800-258-2436 Ext 26/METHOCEL.
Dow Chemical USA
Chemicals and Performance Products
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MIDLAND, MI 48674
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