It is widely believed that only pure water is required to calibrate refractometers. That fact is true of many refractometers, and is certainly appropriate for routine calibration, but it assumes that they were manufactured correctly and have not been damaged since manufacturing. As...
Look at it through crossed polarizers - tempered glass usually shows a lot of strain bifringence. Get some polaroid material (cheap plastic clip-on shades will work) and view through the glass with one sheet on each side rotated 90 degrees to each other. For instance, clip on one pair to your...
With a generator it's always best to have more than you think you need
power go's out for a few days or weeks in winter or summer and you need ac or heat just to sleep or you want to turn on the tv to see whats going on or run your computer
you want to try to keep your load at 70% of the...