My New Toy

I broke my third or fourth hydrometer during my last brew session in late November. A hydrometer is an instrument used to measure the specific gravity of wort. They are made of glass and consist of a cylindrical stem and a bulb weighted with lead shot to make it float upright. The wort is poured into a tall tube and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer is noted. The hydrometer contains a paper scale inside the stem, so that the specific gravity can be read directly. I check the specific gravity before and after fermentation, and the difference gives me an indication of percent alcohol in each batch of beer I brew.

Unfortunately, the glass tube offers little resistance to concrete when dropped from waist level. This has been the case in each of the 4 instances I dropped mine. So I decided to upgrade to a refractometer. A refractometer is an analog instrument used for measuring a liquid's refractive index. It works on the critical angle principle by which lenses and prisms project a shadow line onto a small glass recticle inside the instrument, which is then viewed by the user through a magnifying eyepiece. Wine makers use this instrument to check the sugar content of grapes.

No batteries, no glass stem, no problem! Instead of filling a tube with liquid, I placed 3 drops between the measuring prism and cover plate. Light traveling through the sample is passed through to the reticle. The net effect is that a shadow line forms between the illuminated area and the dark area. It is where this shadow line crosses the scale that a reading is taken. My wort came in at 16.8 on the Brix scale. Now if I could just find someone in the wine business who could convert from Brix to degrees Plato like my hydrometer used to indicate...

My new refractometer alongside one of my older hydrometers