Poor Water Resistance of Latex Products

Manufacturer: Some of our customers are complaining that our latex products have poor resistance to water. How could we improve this?

John Woon (Senior Latex Consultant): Rubber products made from natural rubber or synthetic rubbers are generally considered to be water resistant because of their water repelling properties especially when compared to textile materials, paper, wood and leather.

However, you must take note that all rubber products do absorb water to a certain extent. If your customers are comparing your products with your competitors' products which are made from the same rubber, you need to look at your latex formulation and the manufacturing process to minimise the levels of all water soluble hydrophilic materials. Examples are coagulant, wetting agents, fatty acid soaps, KOH and other naturally occurring water soluble non-rubbers.

I suggest you look into improving your leaching process. if you are using potassium soaps as latex stabilisers you might want to change this to ammonium soaps as thses would revert to fatty acids on drying making the rubber less water sensitive.

In order to measure the sensitivity of your product, you could immerse cut pieces of known surface areas in water at both ambient and elevated temperatures and measure the water absorbed in terms of weight per unit surface area after a given period of immersion. You could also measure the physical properties before and after water immersion.