Performance Characteristics of Gels
There are numerous performance characteristics that define a gel. Each of these characteristics plays a part in determining the function of the gel.
Whether it is a Top Gel, Base Gel, Sculpting Gel or Builder Gel, some of these characteristics include; viscosity, rheometry, appearance & color, cure time & exotherm temperature, and shine. The workability or ‘working characteristics’ of the gel would be defined largely by the viscosity & rheometry of the gel. Here is a brief description of each of these characteristics:
• Viscosity is defined as resistance to flow of a fluid. Most of us would think of it simply as the flow, or fluidity of the substance. The less viscous a fluid is, the greater the ease of movement. Substances with a low viscosity would be thin, like water. Substances with a high viscosity would be thick, like honey. Viscosity can be affected by a number of factors, most notably temperature.
In the laboratory the viscosity is checked by running a sample of a specified amount, at a specific temperature on a Viscometer (pictured below). A sample of a Viscosity Profile is shown below:
* cP stands for centipoise (basically a measurement of viscosity) – the higher the cP, the more viscous the gel.
By looking at this graph, we can easily see how temperature can have a great effect on the viscosity properties of the gel. The higher the temperature, the less viscous (more fluid) the gel becomes. A technician can easily see the difference in viscosity of product with a visual examination. Tilt tube from side to side slowly to see how the material flows in the container. Drop a brush into the gel and see how quickly it sinks in.
• Rheometry is a measure of viscosity as well, as it is a function of the flow of material. Rheometry, however, is the measure of the fluidity of material due to the effect of other factors, such as forces and stresses that affect the elasticity and the fluid mechanics of the substance. Stated in simpler terms, how actions, such as mixing or shaking, affect the flow of the gel. For example, gels described as Thixotropic are thick (viscous) under normal conditions, but flow (become thin, less viscous) over time when shaken, agitated, or otherwise stressed.
In the laboratory the Rheometry is checked by running a sample on a Rheometer (pictured below). A sample of a Rheological Profile is shown below.
By looking at this graph, we can see how a gel may or may not be effected by the amount of shear (usually mixing) applied to the gel. Mixing has a great effect on Gel C, whereas it has little effect on Gel B and a moderate effect on Gel A.
A technician can easily see the difference in thixotropic properties of product by working with the gel. Using a brush to gently message the gel, the technician will notice a thixotropic gel will become more fluid the more it is worked with the brush. Doing this will often increase the self leveling of a gel (especially in sculpting gels) once applied to the nail.
Overall, the workability is how a gel performs when a technician dips their brush into the jar. Some gels are made to keep there shape and some of them are made to self level. The unique chemistry of the gel, including the viscosity and rheometry help create the perfect performance characteristics for the function of a particular gel.