https://books.google.co.uk/books?id=KimqCBg0s8QC&pg=PA419&lp...

Gravitational droplet sedimentation or creaming occurs when the densities of the two phases of the emulsion are dissimilar, and the viscosity of the emulsion is low enough to allow the droplets to move. To prevent phase separation in cases where the phase densities cannot be changed, it is common to increase the viscosity of the emulsion, either by dissolving thickeners in the continuous phase, or formulating the emulsion with a high volume fraction of dispersed phase so that droplet packing itself gives rise to higher viscosity.

http://www.particlesciences.com/news/technical-briefs/2009/e...

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Note added at 47 mins (2017-01-03 17:56:49 GMT)
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Using the centrifugal stress as the instability source, this experimental procedure provides remarkable information about the system stability since it accelerates the rate of creaming or sedimentation of the products (22).

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2974161/

'natas' = creaming
'posos' = sedimentation

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Note added at 51 mins (2017-01-03 18:00:18 GMT)
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Sedimentation and creaming are two analogous phenomena, but in one case, "particles" in the liquid have a density higher than the liquid, and in the other case, the density is lower. In other words, in one case, particles fall, but in the other case, they float.

https://www.agroparistech.fr/IMG/pdf/sedimentation_creaming....

Creaming, in the laboratory sense, is the migration of the dispersed phase of an emulsion, under the influence of buoyancy. The particles float upwards or sink, depending on how large they are and how much less dense or more dense they may be than the continuous phase, and also how viscous or how thixotropic the continuous phase might be. For as long as the particles remain separated, the process is called creaming.

https://en.wikipedia.org/wiki/Creaming_(chemistry)

Creaming or sedimentation occurs as a result of the density difference between the phases. This process results from external forces usually gravitational or centrifugal. When such forces exceed the thermal motion of the droplets (Brownain motion), a concentration gradient builds up in the system with the larger droplets moving faster to the top (if their density is lower than that of the medium) or to the bottom (if their density is larger than that of the medium) of the container. In the limiting cases, the droplets may form a close-packed (random or ordered) array at the top or bottom of the system with the remainder of the volume occupied by the continuous liquid phase

http://doclecture.net/1-65857.html