Hanna Instruments digital refractometer for wort gravity on the scales brewers use, one model.
HI96841
This Hanna Instruments digital refractometer measures wort gravity on the scales brewers use.
A refractometer needs two drops where a hydrometer needs a full cylinder, which is why it is the instrument used on the hot side: sparge, boil, knockout, all measured without pulling half a litre out of the brew.
Light bends by a different amount depending on how much is dissolved in a liquid. A refractometer measures that bend and converts it to a concentration scale. It needs one or two drops, gives an answer in seconds, and has no reagents and nothing to consume.
A digital instrument compensates for temperature automatically, which is the difference that matters: refractive index shifts with temperature enough that an uncompensated reading in a warm room is simply wrong.
Once fermentation starts, alcohol distorts the refractive index; from that point a correction or a hydrometer is required.
Supplied as one model.