Wetting Property in Latex Dippingg Technology

Manufacturer: We are a bit confused when we were told by some experts from one of our universities that dipping technology using latex can only be successful if the wetting of the coagulant and latex is optimized, with the right surface tension of the liquid and surface free energy of the substrates. Can you please explain is simpler terms for our understanding?

John Woon (Senior Latex Consultant): The university's experts were right. The success of the dipping process depends a lot on the principles of “wetting”, i.e., how well the coagulant wets the former surface to achieve an even coating of the coagulant and hence subsequently, an even coating of latex on the former.

For good wetting property of a liquid over the surface of a solid, the liquid must have a low surface tension while the solid must have a high surface free energy (or surface energy). 

The more “polar” the surface is, the higher is the surface energy. Surface energy of solid surface must always be higher than the surface tension of the liquid, in order to achieve good wetting. In the manufacturing of latex gloves, this simply means that the coagulant must have low enough surface tension of around 30 to 32 Dynes/cm while the formers must have clean and uncontaminated surface.

Former materials with high free surface energy (e.g., 200 to 1000 Dyens/cm) include metal (aluminium, steel), glass and ceramic. Plastic formers have the lowest surface energy (usually below 60 Dynes/cm) unless it is modified by some treatments.