Using pre-formulated gels in different cosmetics galenics

 It is introduced in the form of a gel, with other excipients to confer the product the thicker appearance. Its rheological properties, in terms of consistency and cohesion, are very sensitive to the formulation factors, to the concentration of the carbomer and to the manufacturing process, namely, the temperature and the speed of agitation. 

For the fabrication of a gel based on carbomer, two steps can be critical if they are not well mastered. The first step consists of the hydration of the carbomer, which allows the passage of the powder state (the structure is in a very windy form, low volume) to the hydrated state, in which the polymer gradually begins to unfold and gain volume. During this stage, the carbomer will become more and more sensitive to mechanical constraints. Depending on the speed of agitation and the temperature, the gel can be different. The second step consists of the neutralisation (step of gelation) which forms negative loads along the chain and causes repulsive forces and continues to unfold the structure of the polymer with increased volume and viscosity. The quantity of neutraliser used can be fatal for the gel’s viscosity (the gel can break if the concentration of NaOH is too high). The gel must rest for 24 hours in order to gain a stable pH.1,2

The control of the process of manufacturing polymer-based gels remains a difficult task for the formulator, given the large number of factors likely to alter their rheology behaviour (carbomer concentration, pH).