- 1000 OR 2000 mL Pyrex flask, growler, or 1 gallon cider jug
- small soup or saucepan if you're not using the flask
- scale - preferably one with metric measurements
- dry malt extract (DME) - a 1 lb bag is plenty
- measuring cups
- airlock or foam stopper
The whole point is to build your yeast population to a large enough number so that you can reduce lag times, reduce the risk of contamination, and ensure a more complete fermentation. Wyeast smack packs and WhiteLabs tubes are supposed to be pitchable, but for higher gravity beers and lagers starters are almost a necessity. Even smaller brews can benefit from a starter. If you're going to drop the cash and spend the time brewing your beer, why not give it a better chance of being successful right? A starter is just a mini batch of beer, where you're giving your smack pack or whatever more food so that the yeast inside will gorge themselves, multiply their population, and get primed for fermenting your precious wort.
First, you need to determine the size of your starter. If you want to really get technical you can check out the pitching calculator at the Mr.Malty site on my links, but I never do, too technical for me. Basically, you want to make a starter that has an OG of around 1.035 or so. As far as how big you want to go, that depends on your beer. Right now I am building up a culture from the bottom of a bottle of Chimay for a dubbel I'm brewing in the future, so I started with a half-liter starter, let it go for 2 days, then did another half-liter, then I'll step up again to a liter and maybe do that again. For most brews that's probably not necessary, especially if you're starting with a smack pack. Most of the starters I've done have been a liter for beers between 1.040 and 1.065, and 2 liters for bigger brews.
To get a gravity around 1.035, the easiest way to do it is to go metric. A simple ratio of 1 gram DME to 10 mL of water works out to about 1.035. So, measure out 100 grams of DME to 1 liter of water and you're good to go! If you are anti-metric, you'd need a little under 4 ounces DME for 1 quart of water. You can get a cheap digital scale at Target.
Now you're ready to boil, so let's talk containers. You can use one of the Erlenmeyer flasks that Northern Brewer sells (I have one), but it is not a necessity. The advantage to those is that if you have a gas stove or electric coils, you can put the starter mix right in the flask, boil it in the flask, cool it, then dump the yeast in. I have a smoothtop electric stove and have seen Kristen make a Pyrex mixing bowl explode on top of that, so that worries me a little. The other thing I don't like about the flasks is that they are narrow at the top so you can get a really fast volcanic boilover even with the little amount of wort you're boiling, and that's a PITA. I just put it in a saucepan and boil it for 15 minutes. Then I pour the starter into a standard half gallon growler that you can get at any brewpub. A one gallon cider jug would work fine too.
When your starter is cooled enough so that it's no longer warm to the touch I flame the lip of my sanitized growler, put in the sanitized funnel, dump in the yeast, throw the airlock on, and shake like crazy. Some people have stirplates that continously stir the starter which is really good for the yeast, but I just swirl it every time I walk by. The key is to not let your yeast drop out of suspension so that's what the swirling is for. You don't have to go nuts with it, but do it when you can. This keeps the yeast active so that they keep reproducing. Oh yeah baby, asexual reproduction! As far as temperature goes, keep it around room temperature. Some people say you should keep the starter at the same temperature that fermentation of the beer is going to happen, but for a starter you're just building cell counts, so just keep it between 65 and 75 and you're good to go. I keep mine on top of my fridge with a brown paper lunch bag to protect it from light. There's mixed information out there about whether light is bad or good for starters, so I just err on the side of caution.
Now, the big question is, when do you make your starter? There's a lot of conflicting information out there on this one too, and basically the controversy is whether you pitch the whole starter when it's active or do you put the starter in the fridge to crash the yeast and make them settle to the bottom, then pour off the spent wort and just pitch the slurry. I have done both and have noticed the crashed starter took a little longer, but lag time was still under 6 hours. For me, the decision boils down to the size of the starter. If it's bigger than a liter, I'll crash it and decant, if it's a liter or smaller, I pitch the whole thing. I personally prefer having an active starter to pitch, so if I'm going to brew on Saturday, I would make the starter on Wednesday or Thursday. That way I'll have a fairly active starter being pitched into my wort.
Starters do give you some flexibility too. If I made a starter on Thursday but then had to postpone for a week, I would throw the starter in the fridge and then the night before or morning before brewing I would take it out, let it warm up, pour off the spent wort then give it a fresh meal of cooled wort so that it's active. Right now I have half of the yeast cake from my Bourbon Barrel Brown in the back of the fridge. When I know I'm going to use it, I'll wake it up by warming it up to room temperature and then giving it a fresh meal and pitch the whole thing. Well, I see this post has gotten ridiculously long (me, ramble?), so I'll just stop here. Any questions?