How high shear mixing can help improve emulsions

Published: 13-Dec-2022

Silverson Machines discuss how to produce better emulsions

An emulsion is a mixture of two or more immiscible liquids –one being oil based and the other water based, or “aqueous.” They are described as “immiscible” liquids because they cannot easily be mixed together without separating and this can often cause problems during manufacture if it is not done correctly.

Creating a stable emulsion can be a challenging task, even with the use of emulsifiers, but it is a critical stage in the production of many products. The consistency, quality, texture, shelf life and appearance of products are very much dependant on the stability of the emulsion.

In order to form a stable emulsion, whether you are producing an oil-in-water or water-in-oil emulsion, you need to obtain the finest possible droplet size. The mixing equipment needs to impart a large amount of energy into the mix, the more shear energy introduced into the mix, the smaller the suspended droplets will become, creating a fine stable emulsion with both phases completely and uniformly dispersed into one another.

Conventional mixers and agitators, which are suitable for basic liquid/liquid blending, are unable to form a stable emulsion because they do not have the necessary means to impart large amounts of energy into the mix. This type of mixing equipment simply moves the two liquid phases around the vessel, so although it may appear as though the phases have blended, the droplet size hasn’t been significantly reduced, so once the agitation stops the emulsion will soon separate into the two distinct phases once more.

High shear mixing subjects the liquids to intense high-energy which reduces the droplet size sufficiently and allows the two phases to combine, resulting in a stable emulsion which will not separate once the shear energy has been removed. The high shear rotor/stator design of the Silverson mixer is ideally suited to this application and can easily achieve emulsions with a droplet size of 2 to 5 microns. Finer emulsions down to 0.5 microns can be obtained, depending on the formulation.

Silverson Machines offers a range of in-tank and In-Line mixers widely used for preparation of emulsions, from laboratory scale up to bulk production units and repeatability and batch-to-batch consistency are guaranteed.

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