Rubber latex contains water, dry rubber, proteinaceous and nitrogenous substances, carbohydrates, lipids, mineral salts, carotenoids, resins and enzymes. Amount of dry rubber is the important factor. Composition of rubber latex changes day by day due to natural environment reasons such as rain. Metrolac chart is used to find dry rubber content(kg) in rubber latex. Higher metrolac value means latex include high dry rubber content.
Before manufacturing any kind of rubber product, dry rubber content should be set to a certain level. Normally dry rubber content is reduced in many industrial products. As an example, DRC is set to 10% or 12.5% by diluting the field latex. Initally DRC is about 30%. We define this process as standarlization. After refering metrolac chart, factory office decides how much water needs to dilute field latex to a certain value.
Dry rubber is the important constituent in rubber latex. Therefore we have to measure dry rubber content. Metrolac meter and chart is used to calculate dry rubber content. Metrolac chart is a table. Metrolac meter is sinked in latex and read the measurement(metrolac reading). Then we refer the metrolac chart according to the metrolac reading to find dry rubber content. The metrolac values are in columns in the metrolac chart like 80, 100, 120. In rows, dry rubber content in certain volume is given.
You have 5 liter of rubber latex(field latex). Metrolac reading was found as 120. Calculate total dry rubber content in 5l of latex.
Find the related column for metrolac reading 120 in metrolac chart(circled by red colour). One litre of latex
contains 0.34kg of dry rubber. Therefore
Total DRC = DRC of 1 liter * total volume
Total DRC = 0.34 * 5
Total volume = 1.7kg