A surprising truth is revealed.
"6.1.2. Peculiarities in the production of Doppelkaramelmalzbier and Malzbier
Both beers are made in most breweries using the same process right down to the lager cellar.
Both beers are 6% dark beers; with the Doppelkaramelmalzbier, the higher gravity of up to 12% is later achieved by adding sugar.
The bulk contains 3-6% Farbmalz and often 6-8% caramel malt. Part of the colour is always achieved by adding caramel (see p. 92). The addition of hops is small (see TGL) and only serves to round off the taste.
There are several ways to achieve the wort concentration:
The brew is turned out with a gravity of about 6%; by reducing the grist, the brewhouse capacity decreases in fully utilized brewhouses. When using a mash filter a dummy plate must be fitted.
With a normal grist quantity, a wort of about 6% is knocked out; but it needs to be much more must be diluted to reach 6% in the cast wort. This amount exceeds the volume of the kettle, some breweries cook the extra amount in the mash kettle. However, this blocks the brewhouse for longer and water is boiled unnecessarily.
The brew is turned out with a gravity of 9-10%, as far as the pan volume allows. Water is then blended to about get the wort to 6% (reckoned in pitching wort) when transferring.
Benefits: Time savings in the brewhouse, vessel savings in the fermenting room, energy savings because the waste water is not boiled."
"Technologie Brauer und Mälzer" by Wolfgang Kunze, VEB Fachbuchverlag Leipzig, 2nd edition, 1967, page 451.
The surprising truth: Doppelkaramel and Malzbier were exactly the same until after fermentation. Both were fermented as a 6º Plato wort. The only difference is that Doppelkaramel had sugar added before bottling.
There were three options to getting the right strength wort:
1. Create a 6º while mashing by using half as much malt.
2. Use the normal amount of malt but water down to 6º in the kettle.
3. Create a wort of 9-10º Plato and water down to 6º when transferring to fermenters.
Obviously, option 3 was the most efficient use of the brewing equipment.
Handy to see the grist revealed: