Homebrewing Cask Ales
On a recent road trip through eastern Oregon, my wife and I finally got to visit a brewpub that has been on our list for a long time, Deschutes Brewing in Bend. The atmosphere and food were excellent, but obviously the star attraction was the beer. Getting to drink Mirror Pond, Black Butte Porter, and Obsidian Stout at the source was an unforgettable experience, though one beer in particular triggered that unique homebrewer war cry — “I have to brew that!”
Deschutes’ Bachelor Bitter showcases complex toasty and nutty English malts, an earthy and floral hop bouquet and complementary fruity esters from the yeast. The brewery emphasizes each of these characters by serving the beer on cask, as would be done with traditional real ales in Great Britain. The lower carbonation and cellar temperature make this 5.3% ABV beer drink very smoothly and we had no trouble downing a couple of pints in addition to all the other tasters that night. As we passed back through the area on the return trip, we filled a growler to go.
While I have drank craft beer “on cask” at many breweries in the past, that generally entailed the brewer simply putting some of their regular carbonated beer in a firkin (a vessel holding approximately 11 gallons (41 L) of beer), serving it slightly warmer, pulled through a beer engine. Each time I found the experience interesting, but the balance was off in the final product due to the tacked on gimmick. Deschutes, on the other hand, made the cask character an integral part of the beer.
Returning home, thoughts of brewing and drinking real ale consumed my free time. I gathered and read everything I could find on the topic and began plotting my first batch. Those efforts ultimately culminated in a very successful cask party with my friends and family in which we made short work of a cask of standard bitter. The experience convinced me that more homebrewers would enjoy brewing and serving cask ales.
Cask Ale
Britain’s Campaign for Real Ale (CAMRA, www.camra.org.uk) movement defines real ale as “a natural product brewed using traditional ingredients and left to mature in the cask (container) from which it is served in the pub through a process called ‘secondary fermentation.’” As such, you can see that homebrewed beer that is carbonated in the bottle through the addition of priming sugar already shares a lot of traits with this packaging and serving technique.
Beyond this fairly broad definition, most drinkers would recognize real ale as typically having a lower carbonation level than most lagers and American ales, served at cellar temperatures (~50 °F/10 °C), appearing brilliantly clear and showcasing the yeast character. All this leads to a supreme drinkability across many pints. (And of course, pints of cask ale are the original session beers.) Oftentimes drinkers will identify a unique character in the beers at their favorite pub that develops over the time the cask is consumed.
Why would a homebrewer want to make cask ale at home? The most obvious reason is the same reason we brew anything. There are many styles of beer that are best experienced in their original cask form including English pale ales, Scottish and Irish ales, English brown ales, porters and stouts. In the US, we often have to settle for less than fresh bottled examples (which are often higher gravity and carbonation than their draught counterparts) or Americanized interpretations. Homebrewing is a way to drink something we could not easily buy.
For homebrewers who do not have the space, funds or desire to have a dedicated kegerator, packaging in casks provides a great option for sharing a large amount of beer at once. Rather than cleaning, filling, and conditioning 50–100 bottles, you just deal with one cask. During conditioning, you treat the cask like a primed bottle, leaving it somewhere at around room temperature to carbonate. Any closet should do just fine. When it comes time to serve, you only need to chill the cask down in a fridge or cellar for a short period of time. As I will describe below, the serving equipment is minimal and easy to maintain.
Finally, cask ale fascinates people. While I seldom have trouble attracting a crowd of friends to a party with free beer, the turnout for my first cask party was astonishing. I had naively worried that the cask would go to waste because I would not get enough beer drinkers to finish the entire 5 gallons
(19 L) in one night. To my surprise, a little over an hour after tapping the beer, I started seeing signs the cask was on its last legs. People eagerly downed multiple pints and the low alcohol level kept the discourse civil. I think they really enjoyed participating in something special and ultra-local. Few had experienced true cask ale and discussion between brewing friends and non-brewing friends was lively.
The Language of Real Ale
Most of the individual ideas behind serving real ale are not new to homebrewers, but much of the terminology is. Here’s a quick guide to help you tell your spile from your bung hole.
Real ale and CAMRA — Real ale is ale conditioned in and served from a single vessel. CAMRA is the Campaign for Real Ale, a British group that champions serving real ale in pubs.
Cask, pin, firkin and kilderkin — A cask is the vessel real ale is served from, and casks come in many different sizes. Homebrewers most frequently chose the pin (5.4 gallons/20.4 L) or firkin (10.8 gallons/40.9 L), while commerical pubs often serve from kilderkins (22 gallons/83 L)
Bungs and bungholes — Casks have two holes, called bungholes. The keystone bunghole is on the front head of the cask. This is the hole that is tapped when the beer is served. The shive bunghole is on the body of the cask and faces upward when the cask is filled. The cask is filled through this hole, and is opened to the air when beer is served (unless a cask breather is being used). While the beer is being conditioned, both bungholes are sealed by wooden or plastic plugs called bungs.
Spile — The spile can be thought of as a “bung within a bung.” Once the shive bung is punched to release pressure on the cask, it is resealed by inserting a spile. A soft spile allows CO2 to exit from the cask. A hard spile creates an airtight seal. Bungs and spiles must be replaced with every batch.
Tap — The tap is driven through the keystone bung, and beer flows out through it. The tap may be connected to a simple spout or a beer engine.
Beer engine — A beer engine is a device that allows the barman to hand pump beer from a cask, as opposed to pushing it out with CO2 pressure.
Equipment and Supplies
The equipment for brewing cask ale is no different than what you would use for any other beer. You can brew the beer as extract, mini-mash or all-grain and should expect similar results as with non-cask beers. Along the same lines, primary fermentation does not require any special procedures. Of course there will be different ingredients and techniques unique to the styles you typically cask, but I will cover that later.
Packaging and serving require unique equipment, though. The easiest way to get into cask beer is to purchase a homebrew cask kit that includes a pin cask and all equipment short of a mallet and chocks.
The equipment itself can be broken into three categories: packaging, stillaging and serving. The packaging equipment is what you need to store and age your beer. It comprises the cask, keystone bung and shive bung.
Modern casks are typically stainless steel and very well-built. They come in multiple sizes, but the two most common are the pin (5.4 US gallons/20.4 L) and the firkin (10.8 US gallons/40.9 L). So, the pin holds just slightly more than a standard 5-gallon (19-L) Cornelius keg. The sizes go up from there, but are more appropriate for a brewpub setting that can handle the significant challenge of moving around the increased weight. Pins and firkins cost roughly the same, so the choice really comes down to how much beer you want to brew at once and how much you think you can consume before it stales.
There are two holes in the cask itself that you bung up during the packaging process. The hole in the cask head is the keystone bunghole and the other one is the shive bunghole. The bungs can be either made of traditional wood or the more modern and consistent plastic. As far as I can tell, there is not a compelling reason to use one material over the other, but I chose plastic because I was more confident I could properly sanitize it. Both bungs have a recessed and partially bored out center. Later on you will knock these out and so you will need to replace the bungs for each batch. Their cost is less than that of the required crown caps to bottle an equivalent amount of beer, so this is not a big deal.
Unlike Sankey kegs (and most other modern beer packaging vessels) traditional casks are stored and served in a horizontal position with the heads on the front and back rather than the top and bottom.
Storing the keg, or stillaging, faces the challenge that the cask is round and so would roll around without something to keep it in place. In many commercial settings there are special racks for holding the casks. For the homebrewer the best choice is to make wooden chocks. You need three of them (I will explain why later), but these are the one item I have not found for sale. Making the chocks yourself is simply a matter of cross cutting a 2×4 at a 30 degree angle. You should also trim the tip off the sharpest point so that the chocks do not hit each other when in use. While it may be tempting to make these out of a nice hardwood and apply a glossy finish, in practice rough-cut softwood is better. You want them to be somewhat rough so they don’t slip out of place in use.
Once the beer has carbonated and is almost ready to serve, you will vent the pressure from the keg to get it to the level you desire. Doing so involves knocking the center, or tut, out of the shive bung. You can use a metal punch of some sort or purchase a fancy venting tool that has a blow-off hose. The benefit of the venting tool is, if your keg is over-carbonated, the resulting beer spray will be diverted through the tube into whatever catch-vessel you set up rather than shooting up at you and the ceiling.
Once the keg is vented, your job as cellarmaster involves maintaining the right condition or carbonation level. If the carbonation is higher than intended, you drive a porous wooden peg, or soft spile, into the shive bung. This allows excess carbonation to slowly leave the beer while preventing contaminants from entering the cask. Once the beer is at the condition you want, you replace the soft spile with a non-porous wooden peg, or hard spile, to seal it up. New spiles should be used for each batch since sanitizing the wood would be fairly difficult. Much like the bungs, this is not much concern as they are trivially cheap.
Of course all of this effort is for naught unless you can get the beer out of the cask and into a glass to drink. This is where the traditional tap comes in. The tap has a tapered end that you will drive through the keystone bung. A quarter turn valve controls the flow of beer. Taps typically have either one or two threaded fittings to allow attaching spouts or serving lines. Taps come in affordable plastic or in much more expensive and durable stainless steel. The brass taps common from earlier in the 20th Century have all but disappeared.
Which brings us to the biggest choice you have to make when serving cask beer. Do you want to go simple with a gravity spout or do you want to use a beer engine? While many beer drinkers automatically picture the ubiquitous beer engine when thinking of cask ale, its real practical purpose is for something homebrewers rarely face. At a pub the casks are stored in the cellar and left undisturbed to prevent sediment from kicking up. This cooler room is often a floor below the pub. Rather than have the barman walk down to the cellar to pour each pint, the beer engine (sometimes called hand pump) was developed. Basically the pump is a piston that fills and pours beer when the barman pulls the handle. Luckily this is much simpler for the homebrewer or someone serving at a festival because you can simply station the keg on a table or bar where you will be serving. There is no need for a fancy contraption to get the beer out of the cask as gravity is always at hand. A simple turndown spout can be fixed to the threaded fitting with a washer and nut. Turn the valve and beer comes flowing out to fill your pint glass.
The one trick you can employ with a beer engine that is not available on a gravity setup is using a sparkler. The sparkler is a fitting that goes on the end of the beer engine spout and forces the beer through lots of little holes. This agitation knocks a significant amount of carbon dioxide (CO2) out of solution making the beer less gassy and helping to kick up a head and enhance the aromatics in the glass. Like many aspects of real ale serving, drinkers do not universally accept the use of sparklers. Given the roughly $500 price tag for a new beer engine in the US, it would be difficult to make the case for buying one based on the sparkler effect alone.
The final piece of equipment to consider is something I will not go into much detail about. CAMRA’s definition of real ale does not allow for additional CO2 to be added to the beer, so the cask is simply vented to the atmosphere. As the beer is served from the keg, the air from around the cask is drawn in through the shive leading to oxidation and eventual spoilage. If the cellarman does not expect to serve the entire cask quickly enough, a special valve called a cask breather can be used. Essentially it attaches to the shive and supplies CO2 to blanket the beer rather than regular air. The ingenious design of the valve ensures that the CO2 is at atmospheric pressure to prevent over-carbonation. This could be a good solution for anyone who wants to drink their cask over a longer period of time.
Materials
Cask (pin (5.4 US gal./20.4 L) or firkin (10.8 US gal./40.9 L) size)
Keystone bung (plastic or wood)
Shive bung (plastic or wood)
Heavy wooden mallet
Three wooden chocks
Venting tool
Hard spile
Soft spile
Tap
Turndown spout (or beer engine)
Washer
Nut
Brewing for the Cask
While technically the wort production and fermentation for a beer you intend to serve in a cask is identical to any other beer, there are some things to keep in mind. When brewing any beer you need to consider how all the aspects of the finished beer interplay. There are no hard and fast rules, but consider how to make the best use of the following characteristics.
Cask ale has a much lower carbonation level than many modern beers. Carbonation plays several important roles in beer. The carbonic acid “CO2 bite” is greatly reduced in these beers, so you must pay particular attention to any residual sweetness in the beer, which will effectively be heightened. Similarly, since carbonation can help dry out a beer you may want to replace some of the malt with simple fermentable sugars, as is commonly done in Great Britain.
Finally, note that any roasty character in your beer will shift more towards a chocolate note rather than the acrid quality it can sometimes take in the presence of higher levels of CO2.
Since it is usually served at cellar temperatures, cask beer amplifies otherwise subtle flavors and aromas. Any harsh notes that might be imperceptible at colder temperatures will move to the forefront. Be extra careful with your fermentation and sanitation, as there is less room to hide. That said these tend to be much more flavorful beers than macro-brewed light lagers. The drinker will notice the yeast, malt and hop characters even more than usual. Splurge for quality grains such as the excellent choices from Simpson’s, Muntons, Thomas Fawcett, and Crisp Malting. Choose a characterful English yeast strain and experiment with temperatures that cause them to express their wonderful esters. Consider dry hopping your cask with fresh hops or the freshest quality hops you can find. On the positive side, you will likely be drinking this beer very fresh so you do not have to worry about losing character over time to staling.
In terms of timing, you are likely to be brewing a fairly low alcohol beer (though stronger beers like old ales and barleywines certainly are not out of the question.) As such the time from brewing to consumption is actually quite short. Assuming a healthy pitch of yeast and a vigorous fermentation, you would be racking your beer to the cask with priming sugar after about 7 days and then drinking the final product at the three-week mark. Note that since this is a live beer and there is active yeast in the cask, you do not have to worry as much about acetaldehyde and diacetyl problems you can otherwise get from taking the beer off the yeast too soon.
For my inaugural batch, I tracked down and slightly modified a recipe for traditional English ordinary bitter. (See below for the Oxford-shire Ordinary Bitter recipe.)
Packaging and Serving
Once primary fermentation completes, you are ready to package your beer in a cask. Prepare the cask by cleaning it well. Since the cask has smaller openings that prevent you from reaching into it, as with Corny kegs, you might want to soak it in a hot solution of percarbonate based cleaner such as Powdered Brewery Wash (PBW.) You can gently put in the spile bung at this time to allow the cask to hold a full volume of cleaning solution while standing on one of its heads with the keystone bunghole facing up. Rinse the keg well and then sanitize the shive and keystone bungs.
Use a heavy wooden mallet to drive the keystone bung into the cask to seal it. Do not use a metal hammer or anything that might damage the keystone hole surface because over the long run you may not be able to achieve a leak-free seal. A shot-filled dead-blow mallet can also work in a pinch. Rubber mallets often do not have enough heft and are simply frustrating to use as they bounce away. It takes a surprising amount of force to get the keystone bung to seat completely, so invest in a substantial wooden mallet.
Once the keystone bung is in place set the keg on its side with the shive hole facing upwards. At this point you may want to use the chocks you made to keep the cask from rolling around. Make your priming solution to achieve 1.5 to 2.0 volumes of CO2 and add it to the cask through the shive hole.
Then gently rack your beer into the cask, leaving a small amount of headspace. Seal up the cask by driving the shive bung home with a series of firm hits with your wooden mallet. There is a slight lip on the plastic bung and you want to drive it in all the way till the lip seats firmly against the cask. On my first attempt, I was shocked at how much effort this took but that was mostly because I was using a light 10-ounce (280 g) wooden mallet. I later upgraded to a 20-ounce (570 g) model, which was much easier to use.
Go ahead and roll your cask around a bit at this point to mix in the priming solution. Carefully inspect the keystone and shive bungs to make sure they’re not leaking. A few good taps should solve any problems. If you are using wooden bungs and observe some leaking, know that they will soak up some beer and swell to seal any leaks within an hour or two.
Now you wait. Just like when bottle conditioning beers, you want to store the cask in a room temperature location to allow the remaining yeast to work through the priming sugar and provide carbonation. This is a fairly forgiving process, though. The biggest things to avoid are storing the keg so cold that the yeast goes dormant without carbonating the beer or storing the keg so warm that the beer starts to degrade. Again, this is no different than when bottle conditioning beers. Carbonation should take roughly a couple of weeks under ideal conditions.
When you know when you are going to serve the beer, you need to plan a few days ahead of the event. Ideally you want to store the cask on its side (with heads facing front and back and shive upwards) in the serving location for as long as possible for the yeast and other sediment to settle to the bottom of the cask. The trick of course is that you also need to get the cask down to serving temperature of 50 °F (10 °C). As a homebrewer I will assume you don’t have a dedicated cellar at this temperature, so I will tell you what I do. I put the cask in a fridge and set the temperature to 45 °F (7.2 °F) then pull it out and set it up in its final location the morning of the event. I cover the cask with an insulating blanket of some form to keep it cool. This is when you will definitely need those chocks you built. Place two under the front of the cask from the sides and one in the back with the sharper point facing forward. Set the keg up to be roughly level.
At least 24 hours before you serve the cask, you need to vent it to ensure you have the right level of carbonation, or condition. It is critical that the beer be at roughly serving temperature since a warmer beer will off-gas too much CO2 (think of the gushing you see if you open a warm beer or serve a warm keg). Start by cleaning and sanitizing the shive bung surface. As mentioned in the equipment section earlier, drive the tut through the center of the shive bung into the cask using a sanitized metal punch or venting tool. Once any initial foaming subsides (which may be almost immediately for a beer that is already close to serving condition) it is time to fine the beer.
The goal of fining is to get the yeast and sediment to drop out and settle inside the bottom of the cask leaving brilliantly clear beer. There are multiple choices for fining agents including isinglass, gelatin and Biofine Clear. I personally prefer Biofine Clear as it is easier to use and is entirely vegetarian and vegan friendly (using it avoids awkward conversations where I would have to ask if people eat meat before handing them a pint of my beer). Follow the directions for your fining of choice, but in general I use about 10 mL of Biofine Clear in a 5.4 US gallon (20 L) pin cask.
Once you have added the fining through the newly created hole in the shive bung, sanitize and gently press a soft spile into the shive hole. Rock the keg back and forth to ensure the fining is mixed well into the beer. Spray some sanitizer on and around the soft spile. You are looking to see bubbles from the gas coming through the spile as it leaves the beer. Check back on the cask regularly and spray with sanitizer to check for active venting. As long as you see a significant off-gassing, the beer is probably too carbonated. This is more art than science and you will learn over time what gets you the results you want. Once visible off-gassing (bubbling) subsides, you want to lock in the remaining CO2. Remove the soft spile and replace it by gently tapping in a hard spile.
To be clear, unless you have a mechanism for keeping the cask at cellar temperatures in its final serving location, it is likely that you will be venting the beer while you store it in a refrigerator. This is not a problem at all. In any case, as mentioned before I move the cask to the serving location the morning of the event to let it settle clear. The finings will be kicked up along with any yeast and will help re-clarify the beer.
In a commercial setting, a cellarman will often tap a beer hours in advance of pouring the first pint to ensure that the disturbance has time to settle. Part of the fun of serving a homebrewed keg at an event is the showmanship of driving the tap through the keystone, so I like to wait till everyone shows up. At a recent event, I had my neighbor who was turning 40 do the honors.
In terms of technique, there’s not much to it. Examine the keystone and ensure it is clean and sanitized, as the middle will be driven into the beer. Either brace the cask or have someone hold it in place. Remove the spile from the shive to vent the keg. Hold the tapered end of the tap against the center of the keystone and square to the keg. Make sure that the threaded fitting and valve is facing the direction you want as it is difficult to adjust later. With everything in place, wind up and land a solid blow on the end of the tap to drive it directly into the cask through the keystone. Be prepared to follow that up with a couple more taps if the first one does not complete the job.
If you are using a gravity spout, attach it to the threaded fitting on the tap with the supplied washer and nut. Connecting a beer engine is beyond the scope of this article, but it is pretty straightforward.
Pouring a beer is a simple task of opening the valve and filling the glass. The spile that you removed during the tapping should remain out as long as you are serving the beer since make-up air needs to enter the keg to replace the beer you drink. If you take a break in serving the beer, immediately replace a sanitized hard spile into the shive bung to ensure that you don’t lose too much carbonation.
If you look at a cask you will see that the level of the tap is higher than the lowest point when in serving position. Left horizontal there will be at least a half-gallon (~2 L) of beer that you cannot pour. This finally answers the question of why we use three chock blocks on the cask. When you have served the cask down enough so that beer will not spill out of the shive hole you want to tilt the cask forward in one smooth motion and then slide that rear center chock forwards. The final position is a little over 10 degrees forward such that the bottom front taper of the cask is effectively level.
Challenges
While packaging and serving cask beer is pretty straightforward once you have done it a few times, it does have some unique challenges. Hopefully my experience and research can help mitigate some of them for you.
Getting the carbonation right can be a bit hit or miss, just like with bottle conditioning. Ensuring you have healthy yeast, carefully following recipes or priming charts, and storing the cask at room temperature go a long way avoiding problems. It is easy to vent off a little excess CO2, but it is not feasible to add carbonation when it comes time to serve the beer so aim slightly on the high side when in doubt.
Beyond nailing your carbonation, the best cask ale is brilliantly clear with all yeast and sediment settled out of the beer. Those things affect the aroma and flavor of beer so it is not simply a matter of looks. If you have haze problems, consider trying a different type or amount of fining. Also ensure that you are disturbing the cask as little as possible shortly before and during serving. If those do not work then consider a different yeast variety that settles out more solidly.
Depending on the resources at your disposal, keeping the cask at the ideal 50 °F (10 °C) can also be a significant challenge. British pubs have come up with all kinds of mechanisms to cool casks that do not have the benefit of being kept in the cellar. Most of these are out of reach of the homebrewer as they involve glycol, pumps and fancy stainless piping. You could, though, make an insulating jacket or cooler to cover the cask. Evaporative cooling is another alternative and relies on a damp towel on the cask to provide modest cooling. Finally, the old standby of bags of ice works, but pay attention to ensure that you do not accidentally cool the beer too much.
The challenge I thought would be the biggest issue may not be a concern at all. Once you have started serving the keg and drawing air you effectively start a countdown before the beer is spoiled. The exact amount of time you have depends on numerous factors but it is safe to say you have at least 12 hours and perhaps 36–48 hours. On a homebrew scale and without a cellar at a consistent temperature, it is best to plan to finish the keg by the end of the evening. If you want to serve and store the keg for longer than that, you will want to investigate cask breathers and cooling jackets.
Your best option, though, is to invite over your friends, family and neighbors and ask for their help. A pin holds just over 40 pints of beer, so base your number of invitations on this. Make it a potluck or bring-your-own-meat BBQ and you will have an event that leaves a lasting impression.
Recipe
Oxfordshire Ordinary Bitter
(6 gallons/23 L, all-grain)
OG = 1.034 (8.5 °Plato)
FG = 1.005 (1.3 °Plato)
IBU = 47 SRM = 9 ABV = 3.8%
This beer is ideal for the no-sparge method, which emphasizes the malt character. The 6-gallon (23-L) batch size is enough to fill a pin, with enough beer left over to fill a few 22 oz. bottles. Based on the Brakspear Bitter clone recipe from “Brew Your Own British Real Ale,” by Graham Wheeler.
Ingredients
6.75 lbs. (3.1 kg) Maris Otter pale ale malt
1.2 oz. (34 g) UK dark crystal malt (75–80 °L)
1.2 oz. (34 g) black malt
9.5 oz. (270 g) granulated cane sugar
11 AAU UK Challenger hops (60 mins)
(1.45 oz./41 g at 7.6% alpha acid)
0.25 oz. (7.1 g) Styrian Goldings hops (flameout)
0.25 oz. (7.1 g) East Kent Goldings whole hops (dry hop in cask)
1 tablet whirlfloc
White Labs WLP023 (Burton Ale) yeast
2 oz. (57 g) granulated cane sugar (for priming)
10 mL Biofine Clear finings (at venting)
Step by Step
Mill the grains and dough-in targeting a temperature of 151 °F (66 °C). Hold the mash at 151 °F (66 °C) until enzymatic conversion is complete (roughly 60 minutes.) Collect 7.25 gallons (27 L) of SG 1.026 wort. The total boil time will be 60 minutes. Add the bittering hops at the start of the boil and boil for 45 minutes. Add the whirlfloc tablet to encourage coagulation in the kettle with 15 minutes to go. At roughly the same time, turn off the flame, add the granulated sugar. Stir well before turning the flame back on to avoid scorching. Complete the boil and add the flameout hop addition before chilling to 68 °F (20 °C), racking, oxygenating, and pitching yeast. Ferment at 68 °F (20 °C) until fermentation subsides, roughly one week later.
Rack to cleaned and sanitized cask along with priming sugar solution. Condition for roughly two weeks at about 70 °F (21 °C). Chill cask to 50 °F (10 °C) and then vent through the shive. Add finings, plug shive with soft spile, and mix gently. Let the cask settle for at least 24 hours, switching the soft spile for a hard spile as soon as visible off-gassing completes. Set up for final serving at 50 °F (10 °C), tap and enjoy.
Extract Option
Replace the Maris Otter pale ale malt in the recipe with 4.5 lbs. (2.0 kg) of malt extract. Steep the remaining grains for 30 minutes at 151 °F (66 °C) before adding the malt extract. Otherwise follow the rest of the recipe as described above.
