As requested, thanks Andrew! diastatic brown malt, definitely the most interesting and most challenging malt to make. I experimented a lot with this one. My first challenge was to find out what it was. The easy definition: A dark malt that has been dried over burning wood or straw but still has diastatic power to convert itself. It predates the widespread use of coke in malt kilns and predates the use of thermometers. Coke was used to dry malt as early as 1642 but was made more widely available when the means of coke production became more efficient in the later half of the 18th Century. So how did they determine the size of the fire and how dark it could be without destroying the enzymes in the barley? I did come across a few clues in the London and Country Brewer published in 1736 which in describing the production of malt states ” it then must be put on the Kiln to dry four, six or twelve Hours, according to the nature of the Malt, for the pale sort requires more leisure and less fire than the amber or brown sorts” This means that the Pale malt would be dried with a low fire for 12 and the brown malt with a hot fire for 4 hours.
There is another very informative passage about the types of screens used in malt kilns of that era, “There are several methods used in drying of Malts, as the Iron Plate-frame, the Tyle-frame, that are both full of little Holes: The Brass-wyred and Iron-wyred Frame, and the Hair-cloth; the Iron and Tyled one, were chiefly Invented for drying of brown Malts and saving of Fuel, for these when they come to be thorough hot will make the Corns crack and jump by the fierceness of their heat, so that they will be roasted or scorch’d in a little time, and after they are off the Kiln, to plump the body of the Corn and make it take the Eye, some will sprinkle water over it that it may meet with the better Market. But if such Malt is not used quickly, it will slacken and lose its Spirits to a great degree, and perhaps in half a Year or less may be taken by the Whools and spoiled: Such hasty dryings or scorchings are also apt to bitter the Malt by burning its skin, and therefore these Kilns are not so much used now as formerly: The Wyre-frames indeed are something better, yet they are apt to scorch the outward part of the Corn, that cannot be got off so soon as the Hair-cloth admits of, for these must be swept, when the other is only turned at once; however these last three ways are now in much request for drying pale and amber Malts, because their fire may be kept with more leisure, and the Malt more gradually and truer dyed, but by many the Hair-cloth is reckoned the best of all.”
The London and Country Brewer only refers to three types of malt produced at this time: Pale, Amber and Brown malt. These malts were also mixed with each other –
“At Bridport in Dorsetshire, I knew an Inn-keeper use half Pale and half Brown Malt for Brewing his Butt-beers, that, proved to my Palate the best I ever drank on the Road, which I think may be accounted for, in that the Pale being the slackest, and the Brown the hardest dryed, must produce a mellow good Drink by the help of a requisite Age, that will reduce those extreams to a proper Quality.”
There are some people who have researched this subject much more than I have – check out these blogs: The Perfect Pint and Shut Up About Barclay Perkins.
The second challenge: How the hell do I dry malt over fire! I live in a town house, our backyard is a common area shared by our neighbours so I couldn’t build anything or have a fire pit like the fellow did in The Perfect Pint but I found an answer thanks to countless hours of watching outdoor survival videos on Youtube. I could burn stuff in a camp stove and then contain that fire within a smoker so I could have some control over the heat. Initially I had planned to use straw pellets but at $15 per 2 pounds these are a burn. So I went with the wood pellets. Keep in mind that this is my first attempt at this malt so it turned out rather light, I didn’t want to go too dark and kill the enzymes. My next batch will be darker though as I plan to cure it at a higher temperature by using either more gas wood stoves or by burning chunks of maple wood. If you’re interested in making this malt there are some very informative threads on Jim’s Beer Kit page by Ben a.k.a. Fuggledog