1. n. []
A term used to express the results of the methylene blue test, which determines the amount of clay-like materials in a water-based drilling fluid based on the amount of methylene blue dye absorbed by the sample. Results are reported as "MBT" and also as "lbm/bbl, bentonite equivalent" when performed to API specifications.
See: cation exchange capacity, endpoint, ion exchange, kaolinite, low-yield clay, methylene blue test, titration, water-based mud