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klattig

silvery stuff after on-grain distillation

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We recently converted our process from off-grain to on-grain for all our products.  (yes, we've been one of the nuts out there doing bourbon with a beer process!)

We've noticed the appearance of a silvery film in the first column element when doing the on-grain stripping runs.  (we use a 4" column on a 100 gallon still, using two copper perforated-plate bubblers).  We used to see a little of this when using the beer process, but it seems much more present now.  

We've also noticed the presence of some black oily flakes in the low wines, more noticeably at the tail end of the run. 

None of this stuff seems to show up in the spirit runs, so I'm not too worried about it.  But, anyone know what this stuff is? 

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The silvery film is the result of fatty acids and other large compounds forming complex larger molecules. Think of tannins in wine precipitating as the bottle ages. They are harmless and will not make it into your final product.

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black oily flakes are often indicative of a dirty still, for us it was on the condenser side.

Do you ever CIP/chemical clean your condenser? Is your lyne arm removable? As long as you're cleaning receiving tanks, spirit safe, condenser, and still regularly (especially between strips and finishes) you should be okay.

That gunk comes through in the tails because it's more soluble in water than ethanol. I found that rinsing my confessor and line arm out end of the day with my straman hose (hot hot hot city water) then a quick rinse with room temp RO flushes most of that out. We do that in-between strips of the same wash instead of doing full cleanings (we will strip for a whole week then friday and saturday clean with CIP for finishing runs the following week) If you let it go on too long you run risk of Copper Sulfate issues. On grain gives better flavor but it needs much better cleaning protocols IME.

That black gunk is a pain though! After you drain the receiving tank it will stick to the sides, I like to wipe my receiving tank down in between strips after transfer out to keep ahead of it. 

Also, just in case you do, don't leave cooling stillage in your still over night, it will deposit a ton of that stuff in your lyne arm and condenser as it cools. 

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Klattig,  It's sort of off of the subject but a 4" column plate column is way too small for a 100 gallon still.  I bet you have some really long run times with a 100 gallon charge.

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Well, depends on your definition of a long time is!

We use about 12kW to heat, so it takes about 3 hours to heat up, and about 6 hours to run.  We use it mostly for stripping, and therefore never have it in full reflux.  If we tried to run full reflux & make vodka, it would take forever!

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You would not be able to make Vodka even with 5 or 6 runs with that column.  My 100 gallon Baine Marie stills have a 22kW heating system and a 6" diameter column and you can do a stripping run in around 5 hrs.  My steam jacketed stills will do a stripping run in around 3.5 hrs from start to finish.  However depending on your situation a 9 hour run may not be a problem and therefore you would not need a larger column etc.  In my experience both the silvery stuff and the black stuff are lipids.

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Hey Southern,

If you still have black flakes in your distillate after you cleaned the condenser and column it might be charred proteins from the grains. We had a distillery near us have the same experience with on-grain distillation when they  switched (continuing to distill using an electric heating element). I imagine it would be tough for them to get through a column but with enough pressure (which you might have with a large pot and narrow column) they could feasibly make it through. 

They reduced the problem with a silicone wrap on their coils, but ended up switching back to off-grain distillation because they never could fully get rid of the flakes. 

Hope that helps!

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