The Methylene Blue Value (MBV) of fine aggregate is a measure of the amount of potentially harmful fi ne material present such as clay and organic material. Material passing the No.200 (75 mm) sieve is maintained in dispersion with distilled water by mixing with a magnetic stirrer. Methylene Blue solution is titrated into the stirred dispersion in increments until a drop of the mixture on fi lter paper shows a blue ring indicating that the sample can absorb no more reagent. The MBV is simply a measure of the amount of reagent absorbed, and is proportional to the amount of clay or organic material present. Methylene Blue Reagent solution is light sensitive. The solution shelf life is 4—6 months maximum, when stored in a dark cabinet in foil-wrapped amber bottles. The 25g of powder reagent provided in the HM-58 Set is sufficient to prepare solution for over 500 tests. Other required accessories should be ordered if not available in the lab. Weight: 7Kg