Adjustment of zero:
Open the cover plate and put one or two drops of distilled water on the prism. Close the cover plate and press it lightly. Adjust the zero adjustment screw until the light/dark border line coincides with the zero line.
Method of operation:
1. Open the cover plate, clean and dry the surface of the prism with a soft cloth (supplied). Place one to two drops of the solution to be measured onto the prism, using the supplied plastic dropper.
Close the prism plate and press the plate down lightly. Now read the corresponding value where the light/dark border line coincides with the appropriate scale.
2. After taking a measurement, clean away the tested sample which will be on both the prism and the cover plate, using a moist soft cloth. After drying, the refractometer should be stored in a clean, dry environment.
Care and maintenance:
1. Zero adjustment and sample measurements should be carried out at the same temperature – if this varies considerably, then the zero point should be checked and adjusted at least every 30 minutes.
2. Do not immerse the refractometer in water to clean it.
3. As the unit is a precision optical instrument, it should be handled with care. Do not scratch or touch the optical surfaces. Store the refractometer in a dry non-corrosive atmosphere.
4. If the instrument is used in accordance with instructions, the optical performance should not change.
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