Creaming (chemistry)
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Creaming, in the laboratory sense, is the
Where it is important that either the form or the concentration of the emulsion should be stable, it is desirable that the continuous and the dispersed phases should have similar densities and it also is desirable that the continuous phase should be viscous or thixotropic.[1] Thixotropy is particularly valuable in paints, sauces, and similar products, partly because it counteracts tendencies towards creaming. It also is important that the particles be as small as practicable because that reduces their tendency to migrate under the influence of buoyant forces due to Brownian motion, which keeps the particles in suspension.[1] The electric charges on their surfaces should preferably tend to be uniform, so that the particles repel rather than attract each other.
Creaming is usually seen as undesirable because it causes difficulties in storage and handling and can be dangerous in health care settings by causing a
Creaming
A creamed emulsion increases the likelihood of
Creaming of an emulsion also increases the tendency of an emulsion to inversion. This class of process occurs mainly in special cases, when both the continuous and dispersed phases of an emulsion are liquid, as commonly is the state in dairy cream. It is common where the volume of the two fluid components is about the same or the volume of the dispersed phase is larger than that of the continuous phase. The process of emulsion inversion occurs when the dispersed droplets unite, but retain the formerly continuous material as droplets within the mass.
This is an "invert emulsion" or "inverted emulsion", in which the formerly continuous phase has become the dispersed phase and vice versa. Inversion happens in dairy cream when the butterfat concentration is too high and the resulting invert emulsion looks much like butter.
Commonly invert emulsions look much like a paste or thick cream and typical examples are mayonnaise, margarine (especially "low-fat" grades of margarine), pharmaceutical ointments, and cosmetic "creams".
Emulsion inversion differs from emulsion breaking in that a breaking emulsion tends to separate the two phases into un-emulsified continuous phases. Inversion of an emulsion may or may not be difficult to invert, but generally more difficult than creaming.