It’s that time again. Time for James Spencer (host of Basic Brewing Radio) and me to announce another BYO/BBR Collaborative Experiment. This time around, we’ve got an experiment that should be of great interest to all-grain homebrewers -- how does your lautering method affect your homebrew? 

After mashing, brewers separate the sweet wort from the spent grains in a process called lautering. In homebrewing, there are many different ways of doing this. Perhaps the four most commonly used are:

1.) Continuous (or “fly”) sparging

In continuous sparging, the brewer begins to drain the first wort from the lauter tun after the mash has finished and the wort has been recirculated briefly. Once the level of liquid almost drops to the top of the grain bed, he (or she) begins applying sparge water. Ideally, the rate at which sparge water is applied to the top of the grain bed matches the flow rate out of the lauter tun. As such, the liquid level above the grain remains constant. Once the pre-boil volume in the kettle (or other indicator) has been reached, the brewer quits collecting wort. The flow rate is typically adjusted so that collecting the entire wort takes 60-90 minutes. 

2,) Batch sparging

In batch sparging, the wort is collected in two (or sometimes three) batches. After mashing, the brewer recirculates the wort then completely drains the first wort to the kettle, leaving no drainable liquid behind in the grain bed. He then reconstitutes the mash by adding hot water and recirculating, then drains the second wort to the kettle. As commonly practiced, the amount of water added at mash in and when reconstituting the mash is adjusted so that half of the pre-boil kettle volume is collected as the first wort and half is collected as the second wort. Both times the lauter tun is drained quickly because, unlike in continuous sparging, there is no benefit to collecting the wort slowly. 

3.) No sparge brewing

In no sparge brewing, the brewer makes a very thin mash. After the mash rest, the wort is recirculated and then the first wort is drained. If the proper amount of strike water was used, the preboil kettle volume is attained simply by collecting the first wort. As with batch sparging, the wort is drained as quickly as possible in no sparge brewing. 

4.) Brew in a bag (BIAB)

In the brew in a bag (BIAB) method, the mash is performed in the kettle. The grains are held in a large mesh bag, which is then hoisted out of the kettle when the mash is complete. The bag is briefly suspended above the kettle to let any drainable liquid flow into the kettle, but the grains are not otherwise rinsed. Frequently, a thin mash is employed so that the the full pre-boil kettle volume is attained once the bag is lifted out of the kettle. 

Experiment

In our experiment, we’re asking participants to pick two lauter methods and test them head to head. (Go ahead and try more if you have the time.) Experimenters should brew both beers from the same recipe, using same ingredients, on the same equipment (except as needed for experiment) and strive to make everything as equal as possible on the two brew days, with the exception of the experimental variable (lautering type). Given that color and clarity are two variables we will be looking at, a pale beer might be a good selection. However, dark beers are still acceptable. 

One thing to pay special attention to is the pre-boil kettle volume. In both cases, you should collect the same amount of wort from your grain bed, so a fair comparison of efficiency can be made. If continual sparging is one of your experimental variables, it might make sense to brew with that method last. No matter what your pre-boil volume was on the initial batch, you can simply stop collecting wort at that point when you continuously sparge. 

In some cases, your lautering type may force you to have differences between your mashes. For example, in no sparge brewing, you will have a thinner mash than in a continuously or batch sparged beer. This is fine because it is a piece of the experimental variable. (Likewise, your equipment set up will differ if BIAB is one of your experimental variables.) 

What We’re Looking For

The variables we are asking experimenters to record are: 

overall time spent lautering 

total weight of grain bill

pre-boil specific gravity and volume

OG and post-boil volume

relative color of worts (was one darker than the other?) 

relative clarity of worts (was one more turbid than the other?)

comparative color, clarity, aroma and flavor of finished beer 

As usual, we’ll have downloadable forms available at the Basic Brewing Radio website for participating brewers to fill out. The deadline for getting your results to us will be January 8th, so get brewing and help advance homebrewing science!