... or liquid samples, others all can test, such as: powder, board, paper, paste, sheet, clay,etc.A & E Lab. Main Products ... Abbe Refractometer, PH/DDS/TDS Meter, etc.Application:This instrument based on the principle of photoelectric effect & D65 light source ... measured the whiteness value of any substances. Such as: powder, board, paper, paste, sheet, clay, etc.² Chemical & Building materials industry: ...