Stainless Steel Lauter Tun



First, just a brief description of how I brew. I brew all-grain and do 5 gal batches. I mash-in by pouring treated brewing water at 140F over the crushed barley malt in a 5gal single wall SS stockpot (no fittings), stir, check/adj pH. I typically use about 8# 2-row pale malt, 0.5# 40L Briess, and 11qt water. When pH is right and any protein rest is done, I heat "gently with a lot of stirring" to 152F and the set the pot into a box made of Dow Blue Styrofoam (1" thick sides and top; 2" bottom); enclosed in this insulated box it drops only a couple of degrees if left 2hr. At end of starch conversion I heat gently with much stirring to 170F and then use a SS 2-cup scoop to gently transfer to the Lauter Tun. I draw off ~1 qt at a time at the drain, recycling to the top, until the wort is running clear with the fines now trapped in the mash bed. I make no effort to heat the Lauter Tun. I sparge with 170F treated water, gently pouring in a cup at a time just as the surface of the grain bed begins to go dry, collecting the runnings to my TallBoy 8 gal boiler which is heating for the boil even as the remaining wort is drawn off. The boil and hops additions are very ordinary.

My first Lauter Tun was a double-bucket design as described in Dave Miller's first book. They were food grade HDPE buckets, but the large space under the perforated inner bucket was an issue, and the spigot mounted as close to the bottom as the nut allowed still left a substantial volume behind and the dead space held a lot of fines that could not be effectively drawn out and recycled at the beginning and so at the end of the sparge there was considerable lost volume with fines and fermetable content that could not be recovered.

I wanted to have an all-stainless Lauter Tun - stainless is just durable, cleanable, non-extracting gold standard.  From some reading of feedback comments and forum posts, the  the domed false-bottom designs seemed to have a lot of issues about plugging or not draining well. They have fittings to be connected to install/remove the false bottom, and thus there are additional things (pipes, tubing, fittings and threads) that sit in the mash and require cleaning. It just seems more direct to put a drain at the bottom.  I looked in vain for a bottom-draining SS lauter tun and, unable to convince some suppliers that it was a good idea, I set out to build one to see if my ideas were right. What follows is a description of the SS lauter tun I built.


A Lauter Tun was made with components primarily from Homebrew Heaven. Their 5 gal "Brew Kettle" is a well-made basic light gauge SS pot with a non-clad bottom. They (HH) have a SS "bulkhead" fitting and they will drill the pot to accept the fitting at no additional charge. I had the hole put in the middle of the bottom so it will drain as fully as possible. The gasket that comes with the bulkhead fitting was replaced with one cut from a sheet of Teflon since the inner gasket contacts the mash and the composition of the included gasket was not known. A 1/2" SS street elbow was used to redirect the bottom drain to the side, and a section of 8" SS pipe was used to extend to the perimeter where the SS 1/2" ball valve was placed. A 1/2" NPT-M to 3/8" hose barb fitting is used to connect the drain to tubing.  A sheet of SS perf-plate with 3/16" holes was obtained from an ebay vendor (12"sq) and a cardboard pattern/template was used to transfer the pot inside bottom dimensions to the SS perf-plate, and a thin metal-cutoff disc was used on an angle grinder to cut the circle and smooth the edges. A 3/8" strip was cut from a SS (0.030") sheet with snips and then 3" lengths were cut and bent into V shapes; these were set on their sides on the bottom of the pot and the perf-plate/false-bottom rests on this to create the false bottom above the drain. A 10" sq frame of 2x6 was made with a slot in one side to allow the drain to pass through as shown in the first image.

Ideally, the pot would have a shallow conical bottom to allow complete draining, and the bottom would have a band rim as a stand to allow space for the drain fittings. Also, it would be best if the false bottom (perf-plate) had the spacers welded so they remain attached to the bottom and couldn't be lost. In practice, the wooden box frame works well and the vee-shaped spacers work just fine for the purpose. Tipping the lauter tun when finished, the almost dry cake of spent grain tipped out and easily separated from the false bottom and allowed easy cleaning.

I gave it a test run - just another basic ale that I have done many times now - a test for function and yield. It worked great - very free-flowing. I recycled ~1qt at a time back to the top and by the 4 qt point it was entirely clear.  At the end there was only a tiny volume left (<half cup) and I measured 0 Brix with a refractometer so all the sugars were out and that half-cup doesn't matter anyway.. The extract was 7 points higher than I had been getting for the same recipe done in the double-bucket-with-bag-lauter-tun (from Dave Miller's book, first edition) and the clearing was much more efficient.  Easy to clean.

Dave Miller's book states that a benchmark extract using 6-row pale malt is 33 points gravity per pound per gallon; other malts will contribute less gravity; 2-row should give a little less; progressively darker malts would give proportionately less gravity.
8.5#grain/5gal = 1.7 #/gal
1.7#/gal * 33 = 56.1 points gravity, or 1.056 SG, the benchmark.
Using 8# 2-row and 0.5# of 40L caramel I got 1.058, slightly above Dave Miller's benchmark value and a good bit better than my previous yields. Hard to argue with that!

Some may note that this design is not easily heated with a burner from below, but I do not heat the mash in the lauter tun during the sparge and have had no problems with getting good extraction of all sugars, as noted above. For the 5-10 gal batch size things (like moving a kettle to an insulated box) can be done that might be impractical in large batches. After the mash-out heating to 170F the mash is transferred with a SS pitcher to the mash tun - in this case the "mash tun" is really just a nice SS extraction filter. Once loaded, the turbid wort is drawn off at the drain into a SS pitcher 1 L at a time, and recycled to the top until the wort is clear; this point was reached by the 4L point. The 170F sparge water is ladled over the top gently (so as to disturb the grain bed as little as possible) as the surface just begins to go dry. This system drained so freely that I was worried (needlessly) about poor extraction efficiency, and the sparge water was ladled almost continuously to keep up with the draining while still extracting sugars very efficiently. The spent mash cake at the end was nearly dry and not at all sticky. Again, the final runnings (sparging with 4 gal water after mashing in with 11 qts) produced a reading of 0 Brix.

While I have never used one, the style of mash-tun using a domed false bottom with a fitting that removes from below the false bottom to a drain located on the side of the mash tun (whether SS pots or the plastic cooler styles) seems to have several shortcomings. The comments on the product pages for mash tuns of this design have a lot of negative comments about plugging and not draining well. Removal of the false bottom for cleaning with that arrangement requires disconnecting hoses or fittings, and there are many more fittings to be kept clean, and possibly plastic or rubber hose in the hot mash. The picnic drink cooler designs have all of these detractors and additionally the coolers themselves are not rated for use with hot liquids and Rubbermaid has specifically answered questions stating that they do not recommend this use; the plastic for some is marked "7 - Other" and so plasticizers and other things could be leaching into hot liquids; and just because it is BPA-free doesn't mean it doesn't have some equivalent nasty plasticizer included - the info just isn't out there yet....   Rubbermaid is very honest in answering these inquiries directly and honestly; other brands of plastic coolers most likely have the same issues.

The ability to heat a lauter tun from the bottom is a questionable asset. The false bottom would make it difficult to stir well, and strong heat gradients are likely to exist so the mash near the bottom is likely to exceed the maximum amylase temperatures and denature the amylases. Recirculation of the liquid with gentle inline heating would be a much better alternative for clarification and temperature control of larger batches. Fortunately for small batch (5gal) brewers, a separate pot for mashing - one that can sit in an insulated box to hold temperature - or gently heated and easily stirred for temperature boosts - is a very easy solution that is not available to brewers using much larger batches since lifting would be very difficult or impossible with 10 gal and larger batches, and no pumping is required.

This cost me about $130 in parts and a just a bit of time. It works great for the purpose of sparging the mash, and SS is really the better choice......


Dale Callaham

Top 3 reasons NOT to use a picnic cooler mash tun.....

#1 Rubbermaid comment1 screenshot
#2 Rubbermaid comment2 screenshot
#3 It's not Stainless Steel..

Parts List for the 5 gal SS lauter tun

Vendor: Homebrew Heaven Brewing Supplies
1    e200s    SS 1/2" ball valve        $35.40
1    e13s        SS Street Elbow        $4.50
1    c003s    SS 3/8" barb fitting x 1/2"NPT(M)    $5.99
1    c5        5 gal SS brewpot with lid    $39.95
                Shipping $7.95

Vendor: Mainland Valve and Fitting Inc.     (via eBay)
1    Pipe Nipple, 304 SS 1/2" x 8"        $6.34 + shipping ($11.56 delivered)

Vendor:    (via eBay)
Qty: 1    Description: 316 Stainless Steel Perforated Sheet .030" x 12" x 12" - 3/32 holes , Item# 360486416583
Unit Price: $18.52 USD   Total: $18.52 USD  (delivered)

Gently and with a lot of stirring. Some ideas about burners for boiling wort in beer making.  (dac)

I use a 2.2kW electric "hotplate" for beer making. 2.2kW is equivalent to ~7500 BTU/hr. I do this because I have excess solar electricity and propane is expensive. If you have looked longingly at ratings on burners sold for beer making and are feeling inadequate since yours is not as big as the one you just saw in glossy print, this value of 7500 BTU/hr may seem very low. It does heat the mash fast enough that it would burn at the bottom of a very nice tri-clad 8 gal Tall Boy pot unless it is stirred very vigorously, and it heats to a good full rolling boil in good time; possibly the electric burner is just much more efficient in transferring heat to the kettle.  It is constructive to think about the effect of intensive heating, especially for setting the mash temperature. If the kettle is hot enough to scorch at the bottom, then you know you killed some of your enzymes that are supposed to do your work. Yes, it takes a temperature difference to transfer heat to the mash, but if you are unknowingly "mashing out" before you start, it can affect the outcome of your mash. Mash is thick so the heat doesn't move well into the mix. Intensive heating of the kettle greatly overheats at the surface of the mash near the kettle bottom, and can denature the enzymes you need. Stirring is also essential: continuous energetic stirring to constantly move new cooler mash to the hot surface at the kettle bottom. Gentle heating may take a little longer but the result may be a positive one. So regardless of the type of burner you use, it may be worth it to dial it back to a modest level, and STIR, STIR, STIR!  And don't get too swept up in that heating power rating since doing right can't ever be an instant process.