Traditional North German Beers

We're still with Narziss's article on the Reinheitsgebot, but this time looking at top-fermenting beers rather than Lagers.

I'll let Narziss speak first:

"3.1.2. Sugar is permitted in North Germany for the traditional top fermented 'Malt Beers'. Today these beers are brewed with 100% malt to a gravity of 8% and fortified after a limited fermentation and filtration by sugar to 12% gravity. The dark colour is adjusted or corrected by sugar caramel (roasted sugar without ammonia). They are not allowed to be sold in Bavaria as 'Beers', only as 'malt-beverages with sugar". Originally they had to be filled into bottles which could be clearly distinguished from beer bottles. After the Eurobottle was used for softdnnks and even wine (the Vichy bottle as well), this issue has been weakened, it is quite obvious, that even in Germany, there are different regulations, varying from country to country, according to tradition. The addition of sugar to the 'Malt-Beers' (Sucrose, Invertsugar, Sugar Caramel) has to be declared on the label. The sales figures are in ihe region of 1.5%. but they decrease each year. Sugar and saccharine are used in certain areas of North West Germany to fortify the taste of the 'plain beers' (Einfachbiere). They are called 'Sweet' or 'Caramel'; the colour is dark and the gravity in the range of 2.0-5.5% P. They follow an old tradition in this part of the country and are not allowed to be distributed to other areas. The content of sugar and of saccharine must be displayed on the labels. The production of 'beers' containing sugar is supervised by excise officers and controlled by government laboratories as well. The same regulations apply to weak beers which are sweetened with sugar and saccharine. The demand for these beverages is also declining (below 0.03%).

Table II gives a survey on Traditional North German beers which had been on sale before 1914. between the wars and which are available in some areas still today."

TABLE II. Traditional North German Beers
	Name	Strength	Alcohol	Notes
l.	Malt	12% Plato	1.5% w/w	30% sugar plus caramel limited fermentation
2	Fresh or young	Various	_	'Green' beer finished in the household
3	Spontaneous fermentation beers	Strong	Various	Contained some unboiled worts acidic stored like wine before consumption
4	Plain beers (dark)	2-0-5-5% plato	Limited fermentation	Sugar and saccharine added
5	Berliner Weissbier	7-0-8-0% plato	Lactic acid and yeast fermentation +-2% w/w	50% Malted barley 50% Malted Wheat
Today only 5 have survived the sales of 1 are approximately 1.5% of total volume and Ihe others have practically vanished.

Journal of the Institute of Brewing, Volume 90, Issue 6, November-December 1984, page 353.

I'd best re-translate the names back to German before we go any further.

Malt Beer = Malzbier
Plain Beer = Einfachbier

You may notice a similarity between the beer styles mentioned above and those in Dörfel's 1947 manuscript:

Groterjan top-fermenting beer types
beer type	real extract	ABV	OG	special features
Malzvollbier	7-10	1.2-1.8	11-11.5	Includes sugar colouring and sugar
Caramel Einnfachbier	1-2.4	0.7-0.9	4	Includes sugar colouring and Dulcin sweetener
Jung Braunbier	1.8-2.3	0.7-1.2	2-3	Includes sugar colouring and sweetener
Berliner Weissbier	2.7-3.4	2-3.5	7-8	Barley malt and wheat malt, 0.25-0.4% acidity
Feinbitter Starkbier	12	1.2-1.4	16	Includes sugar colouring, heavily hopped, low degree of attenuation
Porterbier	7-9	5-7	18-22	Includes sugar colouring, heavily hopped, more alcohol
Source:
Die Herstellung obergäriger Biere und die Malzbierbrauerei Groterjan A.G. in Berlin, by Braumeister A. Dörfel, 1948, page 20.

I'd always known that Bavaria had a tighter form of the Reinheitsgebot, but not that some products which could be sold as beer in northern States had to be relabelled for Bavaria. I wonder if that's still the case?

I keep having new surprises in relation to old German top-fermenting styles. Today's is the inclusion of spontaneously fermented beers. I'm trying to think what the hell it could be. I know that Gose was spontaneously fermented in the 18th century, but by the 19th century they'd worked out how to brew it by pitching both yeast and lactobacillus, much in the manner of Berliner Weisse.

These styles have been in decline for a century at least. The biggest surprise is that they have hung around at all. But they have. Here are the figures of sales by type in 2009 - 2010:

Off sales by beer type 2009 - 2010
	market share			quantity in hl
	2009	2010	Change in %	2009	2010	Change in %
PILS	55.2	55.1	-0.2	30,566,810	29,860,950	-2.3
EXPORT	10.1	9.8	-3.3	5,586,580	5,288,690	-5.3
WEIZEN	7.9	7.9	0.5	4,371,480	4,300,890	-1.6
BIERMIX	6.5	6.5	0.7	3,589,820	3,538,490	-1.4
HELL	4.5	4.5	0.2	2,507,100	2,459,470	-1.9
ALKOHOLFREI	3.3	3.7	12.9	1,814,090	2,005,330	10.5
KÖLSCH	1.7	1.7	0.3	929,040	912,740	-1.8
SCHWARZ/DUNKEL	1.6	1.6	-2.3	905,230	865,730	-4.4
MALZ	1.2	1.2	1.7	671,010	668,170	-0.4
ALT	1.3	1.2	-3.9	696,750	655,680	-5.9
LAGER	0.9	1	1.2	522,480	517,950	-0.9
LIGHT	0.6	0.6	-0.7	356,380	346,500	-2.8
BOCK	0.5	0.5	-0.7	286,580	278,550	-2.8
MÄRZEN	0.5	0.5	-1.4	280,790	271,050	-3.5
DIÄT	0.3	0.3	-7.2	157,310	142,900	-9.2
BERLINER WEISSE	0	0	14.8	9,060	10,180	12.4
ALLE ANDEREN	3.7	3.8	1.5	2,054,760	2,042,280	0
Source:
Deutscher Brauer Bund
http://www.brauer-bund.de/download/Archiv/PDF/statistiken/110502%20Marktanteile%20Biersortensorten%202009-2010.pdf

Off sales of top- and bottom-fermenting beer
	market share			quantity in hl
	2009	2010	Change in %	2009	2010	Change in %
bottom	74.44%	73.91%	-0.72%	41,169,260	40,031,790	-2.76%
top	12.07%	12.09%	0.12%	6,677,340	6,547,660	-1.94%
total				55,305,270	54,165,550	-2.06%
Source:
Deutscher Brauer Bund (derived from the other figures)

While I'm going table crazy, I may as well include another table from Dörfel's 1947 manuscript. This one shows production of top-fermenting beer by tax class.

German top-fermenting beer production by tax class 1932 - 1937 in hl
year	Einfachbier 3-6.5º Plato	Schankbier 7-8% Plato	Vollbier 11 - 14% Plato	Starkbier 16º Plato	total output of top-fermenting beer	% of total beer output	total output of bottom-fermenting beer	total output of beer
1932	860,000	123,000	920,000	3,000	1,906,000	5.7	31,532,596	33,438,596
1933	680,000	129,000	955,000	2,000	1,764,000	5.2	32,159,077	33,923,077
1934	752,000	110,000	1,193,000	3,000	2,058,000	5.6	34,692,000	36,750,000
1935	797,000	117,000	1,351,000	3,000	2,268,000	5.7	37,521,474	39,789,474
1936	747,000	101,000	1,490,000	4,000	2,342,000	5.9	37,352,915	39,694,915
1937	919,000	117,000	1,814,000	5,000	2,835,000	6.5	40,780,385	43,615,385
Source:
Die Herstellung obergäriger Biere und die Malzbierbrauerei Groterjan A.G. in Berlin, by Braumeister A. Dörfel, 1948, page 3.

I bet not many of you would have expected that the proportion of top-fermenting beer would have doubled between the 1930's and 2010. It's just one type that's been responsible for that growth: Weissbier. Pre-WW II, it was a rarity, hanging on its finger tips. Now it's the third most popular style in Germany.

Summer of Lager!

The subconscious runs our lives without us realising. That my posts were facing Bavaria with a Stein of Lager in its fist was no coincidence. I suppose it was ineluctable that summer would summon the spirit of Lager.

Which is as good a reason as any to push what I'm totally convinced is the best book ever written about British Lager*.

In a break with tradition, it isn't just a hastily nailed together collection of blog posts. It is that partly, but there's also a coherently-written short history of British Lager at the start of the book.

The book comes in many forms:

• ebook
• paperback
• deluxe hardback
• Kindle

I've got the deluxe hardback edition myself. It looks great. And the cover won't easily get bent or folded.

Not got your copy yet? Then buy Lager! now!





* It's also the only one.

Czech hop harvest 1918 - 1923

Apologies for the recent number overload. I seem to be in a table sort of mood. Must be the hot summer weather.

Just a brief post today, no more than a simple look at a few hop production figures. With the spice of a little compare and contrast.

These are important statistics in a political sense, because they relate to the first five years of Czechoslovakia's existence. I thought it a shame when the country split up for no particularly good reason. I can remember being driven around Moravia by Czech friends and them making jokes when we crossed the "border" into Slovakia. Fewer than 10 years later the joke had turned into reality.

The compare and contrast is provided by similar figures for UK hop production. There should be something that jumps right out at you:  the much worse yield per acre in Czechoslovakia. Even in the best year, 1920, it was still less than half the average yield in the UK. The acreage under hops for the countries was remarkably similar: just over 20,000 acres. Yet in the UK that produced about three times as many hops. I'd love to know the reason for that big discrepancy. Was it just a matter of better farming methods in the UK or were other factors at play?

It's intriguing that the good and bad years are almost identical for the two countries. I suppose with the disruption of the war, it's no surprise that 1918 was the worst year. But in both countries 1920 and 1922 were the top two years, just in a different order.

I can explain why the hop acreage increased in the UK after the war's end. A surplus of hops, caused by falling gravities in the later phase of the war, encouraged farmers to switch to other crops. With the hop market stabilised after the end of the war, farmers saw prospects in growing hops again. Even so, it remained less than the 33,661 acres which had been dedicated to hops in 1914*.

Why did acreage fall in Czechoslovakia? My guess would be something to do with the fallout of the collapse of the Austro-Hungarian Empire. Some key markets for Czech hops - for example Austria and Hungary - were now in foreign countries. Though I know from brewing records that large quantities of Saaz were used in Britain between the wars.

And that's me done. I told you it would be brief today.

Czech hop harvest 1918 - 1923
Year.	Acres.	Crop. cwt.	Average per acre. owt.
1918	21,065	41,346	1.9
1919	21,462.5	87,036	4.055
1920	20,902.5	105,312	5.04
1921	19,182.5	58,066	3.025
1922	19,655	112,842	5.74
1923	19,402.5	60,873	3.135
average	20,278	77,579	3.82
Source:
Journal of the Institute of Brewing, Volume 30, Issue 4, April 1924, page 252.

UK hop production 1918 - 1923
year	Acreage	UK production (cwt.)	yield per acre (Cwt.)
1918	15,666	138,491	8.84
1919	16,745	187,795	11.21
1920	21,002	258,042	12.29
1921	25,133	236,172	9.40
1922	26,452	312,000	11.79
1923	24,893	229,000	9.20
average	21,649	226,917	10.46
Source:
1928 Brewers' Almanack, page 119

* Brewers' Almanack 1955, page 63.

Barclay Perkins Lagers 1940 - 1942

You didn't think I was going to let you off with just two posts about Barclay Perkins Lagers did you? I'm happy to report that we've still a way to go.

This time we're looking at Barclay's Lagers in the first half of the war. I would have done the whole war, but I haven't photographed the one covering the second half yet. It's as simple as that.

Barclay Perkins Lagers 1940 - 1942
Date	Year	Beer	Style	OG	FG	ABV	App. Atten-uation	lbs hops/ qtr	hops lb/brl	boil time (hours)	Pitch temp	max. fermentation temp	length of fermentation (days)	colour
9th Oct	1940	Dark	Dunkles	1055.5	1015.6	5.28	71.89%	4.68	1.12	1.5	48.5º	58º	14	82
20th Oct	1941	Dark	Dunkles	1055.5	1017.0	5.09	69.37%	3.77	0.91	1.5	46º	56º	13	80
18th Feb	1942	Dark	Dunkles	1048.5	1015.4	4.38	68.25%	3.77	0.79	1.5	45.5º	56º	14	96
9th Aug	1940	Draught	Lager	1041.4	1009.2	4.26	77.78%	5.32	0.87	2	49º	58.5º	13	13
18th Oct	1940	Draught	Lager	1041.2	1009.1	4.25	77.91%	5.50	0.92	2	49º	58º	12	13
16th Jul	1941	Draught	Lager	1040.0	1010.8	3.86	73.00%	4.03	0.65	2	45º	56º	14	11
9th Feb	1942	Draught	Lager	1035.5	1008.2	3.61	76.90%	4.03	0.54	2	45.5º	56º	15	10.5
21st Aug	1942	Draught	Lager	1035.6	1009.5	3.45	73.31%	4.42	0.65	1.75	48.5º	59º	12	11.5
17th Jun	1942	Draught	Lager	1035.5	1008.4	3.59	76.34%	4.42	0.63	1.75	45.5º	55.5º	13	13
5th Aug	1940	Export	Export	1047.4	1010.2	4.92	78.48%	6.00	1.08	2	48.5º	57º	13	10.5
9th Sep	1940	Export	Export	1047.3	1010.7	4.84	77.38%	6.00	1.08	2	º	º	19	10
19th Jul	1941	Export	Export	1047.5	1015.2	4.27	68.00%	4.62	0.87	2	47.5º	56º	13	8.5
11th Feb	1942	Export	Export	1042.0	1009.1	4.35	78.33%	4.62	0.81	2	46º	55.5º	14	10
26th Aug	1942	Export	Export	1042.5	1009.2	4.41	78.35%	4.81	0.82	2	41.5º	60º	10	11
12th Aug	1940	Sparkling Beer	Lager	1045.5	1009.1	4.82	80.00%	5.00	0.92	1.5	48º	59º	12	35
14th Jul	1941	Sparkling Beer	Lager	1045.0	1012.3	4.33	72.67%	3.79	0.70	1.5	46º	56º	13	34
7th Aug	1941	Sparkling Beer	Lager	1045.0	1010.3	4.59	77.11%	3.79	0.70	1.5	45.5º	56º	14	29
31st Jul	1942	Sparkling Beer	Lager	1040.5	1009.2	4.14	77.28%	4.00	0.70	1.5	48.5º	56.5º	14	34
Source:
Barclay Perkins brewing record held at the London Metropolitan Archives, document number ACC/2305/1/643.

You'll see in the table that Barclays had introduced a fourth Lager to their portfolio: Sparkling Beer. It's a bit of a puzzle to me. What style is it? The colour is a little darker than their PA (Best Bitter) and XLK (Ordinary Bitter) which were both 26. And its a little lighter than the amber version of X (Mild) and XX (Best Mild), which were both 42. In Lager terms, I guess it's in the range of a Vienna. Though I doubt that's what it claimed to be.

One of the few things I do know, is that it was an early canned beer. Whether or not that the only format it was packaged in, I'm not sure. However, the absence of it in Barclay's pub price lists suggests that it was purely and export beer.

Talking of which, I've handily got a price list from 1942. Which means I can check up on something dear to all CAMRA members' hearts: how good value for money was Lager in comparison to the top-fermenting beers? Or rather, how poor value for money was it? Turns out not to have been such poor value as I expected.

The first table is of bottled beer:

Barclay Perkins bottled beer prices in 1942
	OG	price per dozen small bottles retail (shillings)	pence per gravity point
BS	1041.4	8.5	2.46
IPA	1031.3	7	2.68
Light Lager	1042.5	10.5	2.96
Dark Lager	1048.5	11.5	2.85
Sources:
Barclay Perkins brewing records held at the London Metropolitan Archives, document numbers ACC/2305/01/621, ACC/2305/01/623, ACC/2305/01/624, ACC/2305/01/521/1 and ACC/2305/1/643.

BS was 15% cheaper per gravity point than Dark Lager and 20% cheaper than Light Lager. IPA was 5% cheaper than Dark and 10% cheaper than Light. That's not too bad. But wait until you see the draught beers:

Barclay Perkins draught beer prices in 1942
	OG	Wholesale price per gallon (shillings)	pence per gravity point
A	1027.3	5.17	2.27
X	1028.6	5.67	2.38
XX	1031.4	6.89	2.63
KK	1043.3	8.56	2.37
Export	1042.5	8.50	2.40
Home Light	1035.5	7.42	2.51
Dark	1048.5	9.25	2.29
Sources:
Barclay Perkins brewing records held at the London Metropolitan Archives, document numbers ACC/2305/01/621, ACC/2305/01/623, ACC/2305/01/624, ACC/2305/01/521/1 and ACC/2305/1/643.

Now that is a surprise. Only the A, the weakest Mild, cost less per gravity point than Dark. But there is a caveat. The price list gives the public bar price per pint of the top-fermenting beers but not of the Lagers. It looks as if they didn't have a recommended price. So for the draught beers the comparisons are made on the wholesale price. Presumably landlords had the freedom to boost their profit margin on draught Lager by charging what they fwelt like for it. Or maybe it just wasn't sold in public bars. Lager was still quite posh, so that is a possibility.

Getting back to the beers themselves, you can see that the hopping rate per quarter declined along with the gravity. The per quarter rate eliminates gravity from the equation, so this was a real fall in hopping, not one just keeping pace with the fall in gravity.

Interestingly, the gravities of Barclay's Lagers fell less, in percentage terms, than those of most top-fermenting beers:

Barclay Perkins fall in gravities 1939 - 1942
Beer	Style	pre-war	summer 1942	% change
Dark	Dunkles	1057.6	1048.5	15.80%
Draught	Lager	1043.5	1035.5	18.39%
Export	Export	1049.4	1040.5	18.02%
IPA (bottling)	IPA	1043.9	1031.3	28.75%
XX	Mild	1042.5	1031.4	26.14%
X	Mild	1034.9	1028.6	17.96%
A	Mild	1030.8	1027.3	11.36%
KK (trade)	Strong Ale	1055.8	1043.3	22.40%
BS	Stout	1051.5	1041.4	19.61%
LS	Stout	1046.6	1033.5	28.11%
Source:
Barclay Perkins brewing records held at the London Metropolitan Archives, document numbers ACC/2305/01/621, ACC/2305/01/623, ACC/2305/01/624 and ACC/2305/1/643.

Only A, a wishy-washy Mild with not much to go any further gravity-wise, fell less.

One other point before I finish about fermentation temperatures. In the 1930's, the maximum temperature hit during fermentation was mostly around 53º F, with 56º F the highest. By 1942, it had risen to 56-58º F and the highest was 60º F. I would assume this was connected with the cost of keeping the wort refrigerated. It can't have been a voluntary decision, because after the war fermentation temperatures dropped back to their pre-war level.

Wondering if the brewing techniques and recipes changed? We'll be looking at that next time.

British fungus in Amsterdam

Fancy listening to me drone on about Brettanomyces for an hour? I thought not. How about 40 minutes with 20 minutes drinking then? Yes, I guessed that would tempt you more.

On Friday 5th July 18:00 in De Prael in Amsterdam, I'll be giving a talk on Brettanomyces in British beer. Accompanied by some British beers containing brett. You'll need the liquid refreshment to cope with the torrent of information I'll be spouting.

The beers alone will be worth it: Harvey's Imperial Stout, Courage Russian Stout and Colne Spring Ale (brewed by Ed Wray at Old Dairy Brewery in Kent).

It's part of the Carnivale Brettanomyces taking place on the 5th and 6th July across several venues in Amsterdam.

The talk is limited to 20 participants, so hurry, hurry, hurry, if you want to make sure of a place. You can sign up here.

German Lager styles in 1984 (part two)

We're now moving on to other styles, lumped together by Narziss as "Special Beers". It encompasses Pils, Export, Märzen, Dunkles and Spezial.

We'll start with Pils because, er, that's where I've decided to start. This is what Narziss has to say about brewing Pils:

"Pils Beers and very light Export Beers
They are expected lo be of very light colour and less body; it is the hopping rate that determines the character. Measures lo reduce the 'malt body' and to provide very light colours are shown in Table VI.

Very light malts of an EBC colour of 2.5-2.8 from a kilning temperature of 80°C. made from a low protein content of barley (ca. 10.5%) are used. Water quality including a residual alkalinity -2°G, short mashing procedures with a mashing-in-temperature of 62°C, and high liquor/grist ratio (1:4.5-5). are used. The first wort concentration is 14.5-15%, Plato. Separation of the husks takes place during milling and; they are added to the mash at a late stage. Infusion mashes or two mash decoction systems are used equally for this purpose."
Journal of the Institute of Brewing, Volume 90, Issue 6, November-December 1984, page 354.

Elsewhere in the text he's more specific about the mashing scheme:

"2 Mashes short boiling time (5' [5 minutes] each) or infusion mash (programmed)
Avoidance of prolonged exposure to heat after wort boiling
Efficient reduction of colour during fermentation"
Journal of the Institute of Brewing, Volume 90, Issue 6, November-December 1984, page 355.

You can see that great effort is being taken to keep the colour very pale. Not really surprising when you're brewing a Pils. That including the mashing scheme. He produces a little chart detailing the process, which I've changed into easier to read words. He calls it a high-temperature short-mash system. The German name is more succinct: Hoch-Kurz.

I know the name because I've come across it before. It's identical to the method described by Dickscheit in "Leitfaden für den Brauer und Mälzer" (1953, pages 64 – 66). Dickscheit commented: "The decoction effect is small and beers produced this way resemble those from an infusion mash." Interesting. Do German Pils brewers mostly mash this way? If they do, then the best-selling bottom-fermented beer will have little trace of decoction in its flavour.

Here's that Hoch-Kurz mashing scheme as described by Narziss:

Mashing in at 62º C
stand 30 minutes
raise temperature of mash to 70º C
stand 30 minutes
boil 25% of thick mash for 5 minutes
thick mash returned to main mash but temperature remain 70º C
stand 30 minutes
boil 25% of normal mash for 5 minutes
thin mash returned to main mash and temperature raised to 76º C
stand 5 minutes

Hang on. I haven't shown you the table with the details of these styles yet:

Special Beers
		Light export
Type	Pils	1	2	Marzen	Dark	Special
Original wort %	12.0	12.8	12.8	13.6	13.6	13.3
Colour EBC	7.0	7.5	11.0	24	50	27
EBC BU	35	29	24	24	22	33
Brewing liquor Alkalinity °GH	-2	-2	+2	+5	+10	+12
Mashing procedure	D2	D2	I	D2	D3	I
Mashing-in temp *C	62	62	45	37	37	37
Malt average colour EBC	2.7	2.7	3.5	10	32	15
Malts
Light	100%	100%	100%	40%	10%
Dark				60%	84%	100%
Caramel malt Light			(3%)
Caramel malt Dark					5%
Black malt					1%
I = Infusion mash.
D2 = Two mash decoction
Source:
Journal of the Institute of Brewing, Volume 90, Issue 6, November-December 1984, page 355.

I'll translate the style names back into German so it's clearer what they are:

Light Export = Helles Export
Dark = Dunkles
Special = Spezial

That last one, Spezial, is a style that's been ignored by the anal retentives of the style guidelines committees. They usual lump beers of that type in with Helles. Why should they bother sticking with German definitions? After all, who are the real experts on German beer? Augustiner Edelstoff is a good example, though that's probably less bitter than the one in the table. Paler, too, now I come to look at the colour. Maybe not such a good example.  I've just noticed that the one in the table is darker than Märzen.

It's the grists that most fascinate me. I assume that by "dark malt" he means dark Munich malt. It must be something diastatic, as it's the only malt in Spezial. "Light malt" isn't very specific, either. Is that pils malt or pale Munich malt? It's a shame he didn't include EBC values for the individual malts in this table. Hang on a minute. I should be able to work them out from the average. And, as a real service, I've also included the name of the matching Weyermann product:

malt	EBC	Weyermann
Light malt	2.7	Pilsner malt
dark malt	15	Munich malt I
caramel malt light	40	Carared
caramel malt dark	130	Caramunich III
black malt	1300	Carafa III

The grist of the Dunkles is quite complex, with light, dark, dark caramel and black malt. I think the latter is generally called Farbmalz is German. I know from my time traipsing around Franconian breweries asking stupid quastions that the grist for Dunkles vary enormously, at least amongst the smaller breweries. One of my favourites (Hofmann of Hohenschwärz) is mostly Vienna malt with a little Farbmalz.

Again, it's interesting to see a couple of beers using an infusion mash, one of the Light Exports and the Spezial. I'm wondering why in the case of the latter. As it was dark, what was the reason for not going with a decoction?

Oddly, the normal method of double decoction isn't described. Though the classic triple decoction is included:

Mashing in at 37º C
stand 30 minutes
boil 33% of thick mash for 35 minutes
thick mash returned to main mash and temperature raised to 54º C
stand 15 minutes
boil 33% of thick mash for 30 minutes
thick mash returned to main mash and temperature raised to 65º C
stand 15 minutes
boil 40% of thin mash for 20 minutes
thin mash returned to main mash and temperature raised to 76º C
stand 15 minutes

There is more to come from this article, but not about Lagers. It's about those weird North German top-fermenters.