Friday, 13 June 2014

08:37 – Friday the 13th falls on a Friday this month.

Well, it’s finally happened. Until now, I’ve been making up solutions for science kits in 2-liter Erlenmeyer flasks, 2-liter soft drink bottles, or gallon (3.8 L) jugs. But one of the solutions I need to make up is the Fertilizer concentrate part A for biology kits, which is supplied in 125 mL bottles. A gallon of Fertilizer A is sufficient for only 30 kits, and I need to make up sufficient for 90 kits. Rather than make up 3 gallons (~12 L) of that solution in separate 1-gallon batches, I decided to make up a single 3-gallon batch. That means I need a largish mixing vessel. Fortunately, I happen to have some 19-liter polypropylene beakers on hand, AKA 5-gallon buckets from Home Depot. They’re bright orange, granted, but they’re clean, sturdy, and chemically resistant.

Unfortunately, they’re not graduated, but that’s easy enough to address. My shipping scales have one-gram accuracy and resolution up to 20 kilos, so I’ll simply tare an empty bucket, transfer 11,356 grams (3 gallons) of water to it, and use a permanent marker to draw a line at the 3-gallon level. Actually, I’ll probably just do the line at 12.5 liters and make up sufficient solution for 100 bottles rather than 90.