First all-grain in a bag: 72 percent and a boil-over
My first all-grain batch was brewed in a bag: a single kettle, a fine mesh bag of grain, no separate mash tun, and no idea what I was doing. The recipe was simple on purpose: 5 pounds of pale malt, a single hop variety at 60 minutes and again at 10, and a dry English ale yeast. I heated 4 gallons of water to 160 °F, lowered the bag in, stirred in the grain, and watched the thermometer settle at 152. The kettle went into a sleeping bag for an hour, and when I unwrapped it the temperature had only dropped to 149, which I was unreasonably pleased about.
Lifting the bag out was heavier and messier than I expected. I let it drain over the kettle for ten minutes and then squeezed it with my hands wrapped in a clean towel, which I have since read opinions about in both directions. Preboil I had 3.4 gallons at a gravity of 1.036, which when I did the arithmetic afterward came out to about 72 percent efficiency. I would have been happy with 65.
Then the boil-over. I had the burner on full to get the wort boiling, and the moment the foam of the hot break rose I was indoors looking for the hop scale. By the time I got back a brown sticky wave had run down the kettle, over the burner and onto the garage floor. I lost perhaps a pint of wort and spent the next twenty minutes scrubbing burnt sugar off the burner while trying to keep the boil going. The lessons were immediate: stay at the kettle for the first five minutes of the boil, keep a spray bottle of water handy to knock the foam down, and turn the flame down the instant the surface starts to rise.
The rest went smoothly. Sixty minutes of boil, hops in at the right times, and a chill in a tub of ice water that got the wort from boiling to 70 °F in about 35 minutes with a lot of stirring. I ended up with 2.5 gallons at 1.046 and pitched the yeast straight from the packet.
The beer was fine. A little thin, a little under-hopped, perfectly drinkable, and gone within a month. I remember the boil-over more clearly than the taste, which is probably the right way around for a first batch; the mess taught me more than the beer did.