2. Grow it up

The next step is making a lot of yeast from a little yeast. Besides the Erlenmeyer flask you already have, that takes a scale that reads to 0.1 g and a stir plate with a stir bar.

Buy the five-litre flask first — and ideally only that one. A normal starter is two litres, what a pack from Wyeast or White Labs needs to be enough for 19 litres (5 gal) of beer, and a flask should never be filled beyond about three fifths (3 L in a 5 L flask) because the krausen needs the room above it. Two litres therefore does not fit in a 1000 ml flask and boils over in a two-litre one. For most people the five-litre is both the first and the last flask they buy.

More sizes only become interesting the day you propagate from a slant. The inoculum is then so small that you have to step up in stages — a hundred millilitres, then half a litre, then the full starter — and that is where 250 and 1000 ml belong. They can wait.

The scale is the one thing not to skimp on — it decides how right your wort gravity turns out. Search for precision scale or pocket scale 0.1 g. Stir plates turn up cheap second-hand, and until you have one it works to swirl the flask by hand a few times a day.

3. Keep strains

This is where you go from reusing yeast to keeping strains that outlive the batch they came from. You need agar-agar, glass Petri dishes, test tubes with caps, a pressure cooker, an inoculation loop and a spirit burner.

Want to keep a strain for years instead of months? Then you also need glycerol and cryovials — the freezer bank is this same step, one level up.

Two buying tips that save the most: agar-agar is the same product in an Asian grocery store as in a lab catalogue, at a fraction of the price. And the pressure cooker does not have to be lab equipment — an ordinary kitchen model reaches 121 °C, which is the whole point.

Choose glass over plastic for dishes and tubes: it survives the pressure cooker and can be used again and again.

4. Count cells

This step can wait the longest, and plenty of people skip it entirely. If you want to know exactly how much yeast you are pitching you need a microscope (100–400×), a counting chamber of the Neubauer-improved type, methylene blue and a few disposable plastic pipettes.

The microscope may well be a second-hand school microscope — it is the counting chamber that is the precision instrument, not the optics. Search for haemocytometer if counting chamber gives nothing; it is the same thing.

The plastic pipettes cost pennies each and are what you actually drop with, both when diluting and when loading the chamber. Search for transfer pipette or Pasteur pipette; they are sold by paint and craft shops, aquarium shops and pharmacies. The chamber then fills by capillary action and measures the volume itself: its depth and the area of the grid decide how much liquid you are counting in, not how precisely you dropped the sample in.

A precision pipette is therefore needed less than you think, even though it appears on almost every list like this one and is the most expensive item on the page. What really has to be right is the dilution, and that you weigh rather than pipette: 1 g of yeast sample plus 9 g of water is a tenfold dilution, and the scale you bought in step 2 is more accurate than a cheap pipette. Buy the pipette the day you find weighing tedious, not before.

Methylene blue is sold by aquarium shops and pharmacies.