I was recently gifted a 2nd kettle with valve and thermometer. it's 32 quarts. I was thinking that I could actually do decoction mashes to make a dark ale. so I have many new questions. among the literature I've read none has explained clearly about boiling mash and tannin extraction; so is this an issue? What styles of ale can I make if I'm going to do a decoction mash? What kinds of grain should I be looking at? I recently watched an episode of brewing tv which included a triple decoction which gave me some ideas on how to conduct it but I'm still fuzzy on what I should be doing (besides spending a lot more time brewing)
Decoction mashing is typically done with lagers not ales, and here is a great source of information and videos at Kai's wiki. I believe the theory is that tannin extraction is not an issue during decoction mashing because the pH at that point is low enough to decrease solubility. I have done it with a Czech pils and an Oktoberfest and really enjoyed the results.
Also the thickness of the decoction keeps the wort from absorbing the tannins. The wort is already super saturated with everything else it won't pick too much else up. This was the simple explanation given by a brewer from a local brewery with a decoction kettle. I have made a few ales with a decoction. I used a decoction mash on my Berliner Weisse and love how it turned out. I have found it works well with my oatmeal stout as well. I use a plastic cooler for mashing, so it is also a good way to get my multi step mash temperatures. Wouln't do it with a pale ale or anything I was trying to have a hop presence with.
