The Basics of BIAB
What is BIAB?
In simple terms, Brewing in a Bag is a process of wort creation (see Creating Wort) where a single vessel and a bag are used so as this single vessel can act as what is traditionally known as a hot liquor tank (HLT), a mash lauter tun (MLT, more commonly referred to as a mash tun) and a kettle.
The system is a full-volume method of mashing and sparging. In other words, all water (liquor) required for a brew is added at once instead of in stages. BIAB is not a no-sparge method of brewing as the grain bill is in contact with all liquor for the entire mashing period. In other words, BIAB involves a passive rather than an active sparge.
The Essence of BIAB
With BIAB, the mashing (soaking) and lautering (rinsing) process is essentially carried out as follows...
1. All liquor needed for the brew is added to the kettle and heated to strike temperature.
2. At strike temperature, a bag is added to the kettle and the entire grain bill is added to start the mash.
3. The mash temperature/s is/are maintained by occasional heat applications and stirring for usually 90 minutes.
4. The bag which holds the mash is removed at the end of the mash period or, alternatively, after a mashout. The action of removing the bag leaves the sweet liquor (or wort) in the kettle ready to be boiled.
Further details on the BIAB mashing and lautering process can be found in The Commentary. A podcast is also linked in this thread.
How to Brew Your First BIAB from Start to Finish
The Commentary of The Master Guide explains in great detail how to create a BIAB beer from start to finish. Whilst The Commentary uses a gas-fired BIAB set-up as an example, the procedure and logic can also be applied to Mini BIABs and Electric BIABs. Guides specific to those two BIAB methods can be found in their respective sections.
The Commentary is accompanied by The Calculator and The Checklist [EDIT: These are in the process of being replaced by the BIABacus]. These sections contain spreadsheets and instructions on their use. In combination, the three sections give any brewer all the basic tools and information needed to brew their first BIAB beer.