But enough of my failing mental capacities and on with a plump, juicy quote, as ripe as a golden grain of barley. Here you go:
"Brown or Blown Malt is made by subjecting well-vegetated barley — after the moisture has been duly got rid of — to a sudden blast of intense heat generated by heaping up the kiln fire with oak or beechen faggots or billets. The result is an increase of bulk averaging 25%, if all the conditions are favourable. Owing to the risk and tho high rates of insurance demanded in consequence, this malt is generally made at certain centres by maltsters, the large London breweries being alone able to profitably make for themselves.
Amber Malt is manufactured from ordinary malt which, however, is subjected on the kiln to the colouring and flavouring influences obtained from high temperatures maintained for a relatively long period in the presence of a fairly heavy moisture content. These temperatures range from 160 to 180; or even higher, and with careful preparation the diastase should not be completely destroyed, leaving a D.P. of from 8 to 10 Lintner. Amber malt is valuable in the direction of contributing a "malty" flavour and aroma to stouts, but its employment has been found useful for the same reasons in beer production when using large proportions of maize and rice flakes. Amber malt yields an extract of exceptional brilliancy, and it assists the clarification of other worts by increasing coagulation or "break" due to the degree of caramelisation the malt receives in the special kiln treatment to which it is submitted on the kiln.
Crystal Malt is prepared as follows: after undergoing normal germination on the floors the grain is soaked in a somewhat dilute sugar solution, or any weak solution of saccharine substances. The malt is then cured in the ordinary manner on the kiln and its manufacture completed by methods similar to that adopted — although in a modified form — for roasted or so-called patent malt. Crystal malt yields an intensely malty flavour and aroma peculiar to itself. It is valuable for colouring mild ale, to which it confers improved flavour, an enhanced palate-fulness and an attractive rich colour."
"Brewing and Malting" by John Ross Mackenzie, 1927 , pages 254 - 255.
I collect descriptions of brown malt and its manufacture. "You need hobbies to keep yourself sane." The reverse is true in my case. Ross Mackenzie describes the dangerous method of manufacture used in the second half of the 19th century and the first half of the 20th. Where the temperature of the kiln is suddenly raised by throwing on wooden faggots.
So amber malt aids clarification. I'm not exactly sure I understand why caramelisation should help clarification. Barclay Perkins were very keen on amber malt in the 1920's. It was in all their Stouts and Milds. Whitbread, on the other hand, didn't use it at all. Their stronger Stouts - SS and SSS - had contained amber malt, but these beers had been discontinued during WW I. Courage didn't use it either.
Crystal malt has been used in different ways over the years. Initially it was mostly used in Mild Ales. In the 1920's, Courage included it in the grist of all their Mild and Strong Ales, but not in their Porter or Stout. Truman used no crystal malt in their Burton brewery until after WW II. Lees were the same, only introducing it to their grists in the 1940's. Whitbread occasionally used it in their Porter and Stout, and always in their Milds. Their Pale Ales contained none until 1927, after which it was a constant in their grists. Barclay Perkins confined the use of crystal malt to its Mild Ales and Strong Ales.
It's funny. I always thought of crystal malt as a typical ingredient in Bitter. But that only really became true after WW II.