Refractometers

Which refractometer for brix: choose the scale first

Pick the measurement range before anything else. A sample that falls outside the scale gives you no usable reading, so match the range to the product you test.

The scale also sets your resolution. A wide range spreads the divisions thinner, so a narrower instrument reads finer on lower-concentration samples.

• 0 to 32% Brix, 1% division: general sugar concentration checks.
• 0 to 90% Brix, 0.5% division: syrups and high-solids liquids.
• 0 to 55% Brix digital, 0.1% resolution: fine reads on mid-range samples.
• 0 to 35% Brix digital (ST335A), 0.1% resolution: lower-range work with a refractive index range of 1.333 to 1.426.

Optical or digital refractometer

Optical handheld models have no battery and use ambient light only. You read the shadow line against a scale through the eyepiece. They suit field and workshop use where you want nothing to fail.

A digital refractometer displays the result directly. The listed digital Brix models read to 0.1% Brix with ±0.2% Brix accuracy and take 3 seconds or less. That removes the judgement call on where the boundary sits, which helps when several staff share one instrument. One digital model takes 3 x 1.5V AAA batteries, not included.

• Optical: 0.5% to 1% Brix divisions, no power, accuracy listed as 0.5% Brix on the 0 to 90% model.
• Digital: 0.1% Brix resolution, ±0.2% Brix accuracy, automatic compensation.

Honey refractometer and glycol refractometer: match the application

A honey refractometer reads the 58-90% Brix range and also shows Baume (38-43' Baume) and water content (12-27% water). Water content is the figure most beekeepers and packers act on, since moisture drives fermentation risk. The 3 in 1 scales save you converting by hand.

For a glycol refractometer or refractometer for glycol, the catalog data does not list a glycol or antifreeze scale. Check the individual listing for a glycol or freeze-point scale before ordering for coolant work. For brine and seawater, the salinity models give 0 to 10% (1.000 to 1.070 SG) or 0-28% with the saturation point marked at 25%.

Temperature range and zero adjustment

Refractive index shifts with temperature, so automatic temperature compensation matters. The optical models compensate across 10°C to 30°C (50°F to 86°F). The digital model with the wider window covers 10 to 40°C (50 to 104°F). Keep both sample and instrument inside that window.

Each unit has a zero adjustment, by screw, set on distilled water or fresh water. Salinity units can also be set on a 35ppt solution. Check zero at the start of each session.