[Bidagdha_TADIR]

I wasn't sure which subforum is suitable for this topic, so I am placing it in generic discussion for now; if administrator can direct me to proper area, I will be grateful (if you think this question is not suitable in any forum, please lock it).

So far what I understand about creams and gels is that -

1. Cream is opaque but gel is transparent.
2. Cream is more viscous and thick compare to gel.
3. Cream is an emulsion but gel is a suspension or colloid.
4. A cream doesn't have a structured vehicle but a gel has structured vehicle (a network of polymer inside a vehicle such as water, which when not sheared/shaken has a viscosity approaching infinity).

But then I saw some products on the market (shaving cream and shaving gel to be precise), I couldn't differentiate the cream from the gel.

So, are the differentiations above correct, or are there more proper distinctions?

[Borek]

As far as I can tell gel is reasonably well defined by IUPAC, cream is not, so the name usage can be quite random.

IMHO the only serious difference is the one you listed as point 3. Trick is, it doesn't help, as it is not easy to differentiate between both just by the look.

Emulsions are not transparent because there is a difference in refractive index between both phases. I am guessing here, but if it is possible to prepare oil and water phases with the same refractive index, cream can be transparent as well.

[Corribus]

I don't know about IUPAC, but FDA has specific definitions, related to dosages of drugs.

http://www.fda.gov/Drugs/DevelopmentApprovalProcess/FormsSubmissionRequirements/ElectronicSubmissions/DataStandardsManualmonographs/ucm071666.htm

[Bidagdha_TADIR]

Thank you both. The common gelling agents are HEC, HPC, HPMC, PVP. Since both creams and gels have one or more of these in their formulation, I guess the main difference becomes that one is emulsion and another is not. Thanks for the confirmation.