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Jun 08, 2022 View:

DIY defoamers

I recently tried some defoaming additives because I was having trouble with foaming while stripping barley malt mashes. I had previously used simethicon (silicon oil) with success but I was looking for a DIY defoamer, preferably made from grocery store ingredients.

The test still

I used was a continuous still made of laboratory glassware. This was a good opportunity for testing defoamers since I could see what was happening inside the pot and column.


The still pot was a 2 liter glass flask in an 800 watt heating mantle. The column was a 500mm “thorn” column with the wash injection point 2/3 of the way up the column. The set-up is particularly prone to foaming due to its small volume.


The still was warmed up and brought to a steady state with wash, fed by a digitally controlled stepper motor peristaltic pump.


Each defoamer was mixed into a liter of wash with a blender-on-a-stick.

A liter of wash with the test defoaming agent was run through the still. I observed how well it knocked down existing foam, and the new steady-state foam level. I measured how much of the column was blocked by foam as well as how full of foam the reboiler pot was.


After the 1 liter test, the feed was switched back to wash with no defoamer until the still returned to steady state. Then the next test would begin.


For silicon oil, I used “Five Star Defoamer 105”, 2 drops per liter. This is 1:100,000 dilution, or half the maximum recommended by the FDA.


The other defoamers were various strengths and combinations of olive oil, butter and dishwashing liquid detergent.



BEST (No foam in column, surface of boiling Reboiler wash visible)

               1 tsp olive oil or

               ½ tsp olive oil + 1 drop dishwashing liquid detergent (DWLD)           

OK (foam blocking 2” to 6 “of column)

               ½ tsp olive oil or

               2 drops DWLD


Ineffective (Reboiler full of foam, column full of foam)

               1 tsp butter or

               1:100,000 simethicon


The olive oil, alone or with DWLD, was the clear winner. I was surprised at how poorly the simethicon performed since it is so effective at “knocking down” foam in an open mash tun.


Adding DWLD to olive oil keeps the oil in suspension if the mixture is stirred up with a “blender-on-a-stick”.


this may be dumb question but what is dwld


Reply:1 hour ago, Hudson bay distillers said:

ok lol now i do feel dumb 

Reply:6 hours ago, Avak said:

Try a few slivers of all natural, no additives or scents, based soap (bars). Have read recently that this is a trick used by old school, larger distillers. However, have not tried it myself.


Or just use patcote 376. relatively affordable considering how little you need to use.




I use coconut oil in a test still, but for some reason am hesitant in scaling up with it. It works like a charm in the little guy though. 


I tried soap. It didn't work as well as simethicone so I didn't include it in the formal test. The problem may have been that I am adding defoaming ingredients to cold wash, not a hot still pot. It may be the soap was not dissolving, so not getting to the job site.

Recipes are given per liter of input wash. For instance, my favorite is 100ml olive oil + 1tsp DWLD (dish washing liquid detergent) per 10 gallons of wash.

I have read foaming blamed on CO2 in the wash, accompanied by recommendations to "de-gas" the wash. My test still pre-heats the wash and runs it through a separator to eliminate CO2 before injecting wash into the column. It still foams like crazy. I think the gas inside foam bubbles is water/ethanol vapor, not CO2. At the beginning of a batch run, there are heads vapors as well. I think head vapors are responsible for the rush of foaming seen with a puke, just before the still comes to operating temperature. The reason a spray of cold water kills foam is because it condenses these vapors, not because it makes CO2 disappear.

Received wisdom says protein is the surfactant that cause foaming. I have tried to reduce protein with a protein rest and boil-out during the mash, proteolytic enzyme (Papain) after fermentation, double racking and pre-heating to 97C with filtering before injecting wash into the column. All this made my column and still much cleaner, but didn't help reduce foaming. I wonder if the villain is something other than protein.



Maybe you just need more headroom in the boiler and let it foam. Its not affecting the taste of the finished product, so why bother worrying about it?

Reply:13 hours ago, Glenlyon said:


The still geometry is a major factor of foam.

IMHO - foams tend to climb walls easier than expanding in open space.  

Tall narrow stills will have more problems than fat squat stills.

The nearer you get to the top, the more surface area to stabilize the foam, this includes the roof of the kettle.

You will hit a point where no amount of antifoam will prevent puking, as the high vapor speeds in that limited remaining volume will start to pull what little foam there is - and entrained liquid up the column.

Why exactly are you trying to reinvent something?  There are scientists and companies that devote huge time and resources into this.  Just buy Patcote or another Simethecone and call it a day?  No?


Reply:3 hours ago, Silk City Distillers said:

old moonshiners sometimes added a wee slab of butter....


Yesterday mashed 100% rye malt. Foam was a great problem. Although I added a 4x dose of commercial defoaming agent I got wort flowing out of mash tun/fermenter approximately in 15 minutes after yeast addition. By that time my defoaming agent run out - all remains were already in the wort. So, I used olive oil - 50-70 ml per 60L of wort. In the morning everything was ok. Now the question is - should I add more commercial defoaming agent or should I add more olive oil? Or both?  


putting to much heat to your still will cause an excess of foaming with many types of wash. Old school still men were well known for the their ability to put just the right amount of heat to the still (direct fire) to not have it foam, but still have a decent run time.

Have you tried reducing your heat input?


I've had some luck on the brewing side using anti-flatulence medication.  I know it sounds strange, but the active ingredient (and only ingredient, really, other than stabilizers, just check the back of the box) is polydimethylsiloxane, aka simethicone.  You can find this in any pharmacy store.  The only difference between this and a professional anti-foam agent is that the latter is going to me a stabilized emulsion so it's liquid and thus more easily added to your boiler. 


Turkey Red Oil, which is sulfated castor oil is a 'water soluble oil' that will lower foaming  LOT...  It works as good as fermcap-S IMHO...  I remember an old timer giving me some in a tiny old glass carmex  container 30 years ago and said "if you ever run just water in your cooling system of your car, put just a couple drops of this in for lube"...