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.

How to Achieve Maximum Transparency in Latex Products

Manufacturer:  We manufacture a range of products using both natural rubber and synthetic latex. Our problem is our inability to achieve the transparency requested by our customers. Please advise us as soon as possible.
 
John Woon (Senior Latex Consultant):  All ingredients used should have a refractive index close to that of the base rubber. Accelerators selected should have maximum solubility in the the rubber. Chemical blooming should be prevented.

If possible, ZnO should be eliminated or minimised in the recipe. Improve your leaching would also help.
In response to your request, detailed recommended recipe for the curatives was sent to you separately.