How to Increase Wet Gel Strength

Manufacturer:  We are using both prevulcanised latex and post-vulcanisable latex compound. We also use some synthetic latex such as SBR and NBR. Our process is very sensitive to wet gel strength of the latex. Poor gel strength always lead to high rejection. What shall we do to improve the wet gel strength?
  
John Woon (Senior Latex Consultant):  First of all, prevulcanisd latex has poorer gel strength compared to post-vulcanisable compound and synthetic latices tend to have weaker gel strength compared to natural rubber latex.

When using post-vulcanisable latex compound, enough pre-vulcanisation should be allowed for maximum build up of the gel strength. However too much pre-vulcanisation would also lead to poor gel strength. You have to decide what degree of prevulcanisation is best for your process.

Avoid using prevulcanised latex if maximum gel strength is a must.

The types and level of surfactants you used for latex stability are also important. Extra heating and drying of the gel before proceeding to the next stage of your process would help.