Take for example the practices described by G. Lacambre, whose 1851 Traité Complet de la Fabrication des Bières is the source for much of what we know:
"Boiling of these beers is longer and stronger than uytzet: commonly the boiling of these beers is 15 to 18 and even 20 hours in many breweries."Or my favorite, which is just the second of six paragraphs on the mash schedule for Leuven white beer:
"When the colour is produced purely by a long boil, there is certainly no great harm, but unfortunately there are many breweries today that reduce the boiling time and force the colour using lime which is sometimes, as we have seen, very detrimental to the interests and even the health of consumers."
"As soon all the liquid has been extracted, they remove the baskets, of which there are eight to ten for a tank of 100 hectoliters, and by the underback, they refill the mash tun with completely cold water in summer and lukewarm water.... Once there is enough water in the mash tun it is stirred again very strongly, then they extract the second mash in the same way as I have described the first, and it also goes in boiler no. 1. Once there is no more liquid on the top, the liquid contained between the two funds is drawn off, then, always through the underback, a third infusion is added. The water used for the third mash is drawn from boiler no. 2, which is at this point filled with boiling water. The third mash is mixed until the warm mixture is perfect, then by means of baskets, and operating in the same manner as the first two mashes, they extract the slightly white wort which is poured into boiler no. 1 until the liquid reaches 40 or 45 centimeters from the top; the rest of the mash being drawn from the bottom of the mash tun, is placed in the clarification tank."In sum: breweries regularly boiled their beer for 8-20 hours to achieve a darker color (or other mysterious, unidentified qualities) unless they dosed them with toxic calcium hydroxide. This followed mash schedules (in some beers) so baroque they took dozens of steps and required six vessels. I guess you can see why the lime seemed like a good idea.
1. What happens to hops after a twenty-hour boil?
2. Had they never heard of dark malts in Belgium or did they just like that tweaky lime buzz?
3. Extra credit: was the production of lambic a short cut for slackers tired of 29-hour brew days? (Provide corroborating evidence.)