Another stripping run question

[GNBrews]

I'll start with a bit of back-story. I made a 20L batch of UJSM back in April, O.G.=1.080 --> F.G = 0.998 in just under 3 weeks according to the Tilt. I forgot about it. It's been sitting in the cellar for about 5 months now and had a very good pellicle on it when I opened the fermenter this morning. It didn't smell bad, but definitely had an odor of pears or similar fruity esters. I decided to run it anyway.

I charged the still, attached a short unpacked column and brought the boiler up to temp. This was my very first stripping run experience (have run with reflux before with slower takeoff). I started and pulled 100ml of fores from about 68C to 85C. Even though I wasn't collecting very fast (tiny interrupted pencil lead stream), the head temperature rose very quickly which is not something I'm used to. That 100ml of fores measured 72% ABV.

I switched containers and begun collecting everything else, same interrupted pencil lead stream, but the head temp rose to 91C after only collecting 0.5L or so and stayed around 90-93C for the bulk. I finished when the head temp reached 98C. I collected only 2.5L @ 22% over 2hrs.

That is an abysmal yield for 20L of 10% wash. As I understand, a stripping run should be as fast as your condenser can keep up with. I even opted for a more conservative rate. Something isn't right. Could the ethanol have converted to vinegar? There was a slimy pure white pellicle, but not the SCOBY-looking things that I've seen in refence to vinegar mothers.

Ideas?

[NZChris]

It sounds like you should have run it five months ago. What is the pH of the backset?

[Setsumi]

or a leak. but with all those triclamps probaly not. if my take volume is off a leak comes first to mind, a triclamp sometimes miss align especially if you do not use the seals that comes with them... i use a copper washer with teflon tape... second is wash/mash and fermentation numbers. on a strip. if you are at 98 C on a pot/ strip you shoul be done. if you lost alc due to wash converting to viniger you shoul have tasted it in the wash.

[Wheelspin]

Virtually same thing has just hsppened to me. I will be watching replies with intrest.

[SaltyStaves]

A wash turning to vinegar is rare, but it has a tell-tale sign in that it will burn your nose AND your eyes. When you strip it, that sensation will be ramped up considerably.

[jonnys_spirit]

Slimy pellicle? Did you happen to take any foto’s? Any green fur?

Was it airlocked in anything like a carboy or pretty much open to the air?

Cheers,
Jonny

[GNBrews]

Hi folks. It certainly didn't burn the eyes or nose like opening a bottle of cooking vinegar would. The pellicle was white, with sort of "brain fold" type striations and a few bubbles underneath. TBH, it looked like a lacto soured beer pellicle. I'm kicking myself for not taking a photo, but it's hard to figure out what wild thing is growing without plating it anyway, so all I can say was that it was pretty generic "wild infection" of a souring agent of some sort.

I checked the pH on the spent wash (still cooling) and it was right around 3-4 on the indicator paper. White vinegar from the cupboard is a solid 1-2. If the ethanol did convert to vinegar, it wasn't a very strong solution I guess.

I've never done a stripping run before, so this is all new. I found it really weird that the temp just basically shot up to 91C within the first tens of ml collected. Is it possible for the unpacked column to be too short before the condenser? I've seen other folks with what amounts to a 10-15cm stub off the top of the keg going right into the liebig, so I'm thinking it's not that important?

Thanks all.

Edit: Definitely no leaks. All the bits are clamped well and mirror-checked once up to temp.

[Wheelspin]

Following.

[CopperFiend]

Was the offtake cool to the touch?

[Demy]

Are you sure that the initial product has completed fermentation before stripping?

[Saltbush Bill]

Simple answer is that if that little came out , there was little alcohol in the wash at distillation time ......what happened to it in that 5 months ..or at the time of fermentation is anyone's guess.

[silverbean]

Thats all very weird, none of your data adds up. I should not be possible to get 72% ethanol even on foreshots from a 10% wash in a pot still, you would need closer to 30% in the boiler. At 63 degrees there should be no output but where you thermowell is located that could just be lag, 85C is closer to your 72% ABV but again 30% wash.
The rest of your run the temps indicate a high ABV but the end result didn't. It makes me wonder if the mould converted the ethanol to something with a lower boiling temp and lower gravity. Vinegar has a boiling point of 117.9C so not vinegar. I guess it would be good to check your temp and ABV measuring devices to rule that out.
Your pot still setup looks good but I would rather the thermowell closer to the boiler, even if you just swapped the 2 - 90 degree bends, in the reducer or the boiler itself would be better.
I could be totally wrong but thats the only way I can rationalise it. Pity for a UJSSM to end this way, what generation way it?

[JesseMarques]

Thats all very weird, none of your data adds up. I should not be possible to get 72% ethanol even on foreshots from a 10% wash in a pot still, you would need closer to 30% in the boiler. At 63 degrees there should be no output but where you thermowell is located that could just be lag, 85C is closer to your 72% ABV but again 30% wash.

I do get heads with 72% ABV in a pot still, starting with around 7% wash

[howie]

i get about 70% abv in a pot still from 10% wash as well.
looking at my recent notes, the head temp was up to 91c after collecting 2l from a 27 wash.
the head temp was 97c when it got down to 20%abv.
(i do not run it on temps, i am still trying to note everything)
by my reckoning, you should have got about 4.5l from a 20l wash.
sounds like something has gone wrong with the wash.
did you test it before stripping it?

[GNBrews]

Was the offtake cool to the touch?

Yeah, temp in the collection vial was about 19C.

Thats all very weird, none of your data adds up. I should not be possible to get 72% ethanol even on foreshots from a 10% wash in a pot still, you would need closer to 30% in the boiler. At 63 degrees there should be no output but where you thermowell is located that could just be lag, 85C is closer to your 72% ABV but again 30% wash.
The rest of your run the temps indicate a high ABV but the end result didn't. It makes me wonder if the mould converted the ethanol to something with a lower boiling temp and lower gravity. Vinegar has a boiling point of 117.9C so not vinegar. I guess it would be good to check your temp and ABV measuring devices to rule that out.
Your pot still setup looks good but I would rather the thermowell closer to the boiler, even if you just swapped the 2 - 90 degree bends, in the reducer or the boiler itself would be better.
I could be totally wrong but thats the only way I can rationalise it. Pity for a UJSSM to end this way, what generation way it?

Agreed. Something goofy is afoot. The boiler is still charged with the backset. I'm tempted to heat it back up and run with some reflux and see if there's anything left, but since I reached 98C, I can't imagine that's possible.

The first 100ml definitely came out at 70%. I pulled it fairly slowly. Ramped to 65C at 5500W, then eased back to around 600W to push it over to 78-85C.

It was gen 3 UJSM. I had run the other 2 generations low and slow with some reflux and took cuts. Because this one had the possibility of being nasty, I decided to try the stripping bit. Again, I've never done it, so it seemed really weird to have the temp just constantly rise like it did. I'll certainly try again; it's all in good fun really.

Regarding the probe location. I can certainly switch the elbows around. I was thinking the "point of no return" being right before the condenser, but I suppose I'm not trying for reflux with that config so that's not really applicable.

Thank you for all the suggestions fellas. I think I'm just going to chalk this up to a weird experience and try again.

[MartinCash]

Thats all very weird, none of your data adds up. I should not be possible to get 72% ethanol even on foreshots from a 10% wash in a pot still, you would need closer to 30% in the boiler. At 63 degrees there should be no output but where you thermowell is located that could just be lag, 85C is closer to your 72% ABV but again 30% wash.
The rest of your run the temps indicate a high ABV but the end result didn't. It makes me wonder if the mould converted the ethanol to something with a lower boiling temp and lower gravity. Vinegar has a boiling point of 117.9C so not vinegar. I guess it would be good to check your temp and ABV measuring devices to rule that out.
Your pot still setup looks good but I would rather the thermowell closer to the boiler, even if you just swapped the 2 - 90 degree bends, in the reducer or the boiler itself would be better.
I could be totally wrong but thats the only way I can rationalise it. Pity for a UJSSM to end this way, what generation way it?

I also get fores at or just above 72% in some strips, so "should not be possible" may well be the case, but factors like internal reflux may well bump up the theoretical maximum you can get in a pot still.

I think there might have been a lot of esterification. Ethyl acetate? You should be able to smell it, though. What does your strip smell like?

[Saltbush Bill]

Did you reach 98c.....or did your thermometer just tell you that you had.?

[NZChris]

You're never going to make enough to drink, especially aged, if you leave it that long between generations. I suggest you re-read the UJSSM thread before you put down your next generation.

[Yummyrum]

Simple answer is that if that little came out , there was little alcohol in the wash at distillation time ......what happened to it in that 5 months ..or at the time of fermentation is anyone's guess.

Indeed .

At the end of the day , it’s a bit disappointing after all the initial effort .

Guesses are guesses . I wonder how hot it had been in your cellar over the last 5 months ?
Was the fermenter totally sealed ?
Is it possible that the fermenter become a bucket still and the alc just slowly evaporated

[GNBrews]

I also get fores at or just above 72% in some strips, so "should not be possible" may well be the case, but factors like internal reflux may well bump up the theoretical maximum you can get in a pot still.

I think there might have been a lot of esterification. Ethyl acetate? You should be able to smell it, though. What does your strip smell like?

Definitely full of esters. It was a fruit stand in the fores. The strip is a bit fruity as well, but much more balanced toward sour corn flavors. Not bad actually.

Did you reach 98c.....or did your thermometer just tell you that you had.?

The thermometer did, but it's tested before each run, so I know it's giving me good data. Been down that road before. The distillate was well into the tails by taste as well.

You're never going to make enough to drink, especially aged, if you leave it that long between generations. I suggest you re-read the UJSSM thread before you put down your next generation.

Agreed! Life was just a bit chaotic at the end of April, so some things were put on hold.

At the end of the day , it’s a bit disappointing after all the initial effort .

Guesses are guesses . I wonder how hot it had been in your cellar over the last 5 months ?
Was the fermenter totally sealed ?
Is it possible that the fermenter become a bucket still and the alc just slowly evaporated

Definitely. The fermenter is basically an open vessel. It does have a lid but it's not sealed; basically keeps stuff from falling into it. The cellar stays a pretty constant 18-20, but the fermenter was warmed with an aquarium heater set at 27F for the 3 weeks it took the fermentation to finish. It stalled a bit after 1 week and needed some calcium carbonate to raise the pH a bit. I suppose it could've been evaporating, but I should see that as the final gravity increasing I think. The TILT (electronic hydrometer) plots out a nice spreadsheet and it went down to 0.998 and stayed there.

[shadylane]

The thermometer did, but it's tested before each run, so I know it's giving me good data. Been down that road before.

A suggestion from someone who has also "Been down that road before"
Don't trust the thermometer until it accurately reads the vapor temp from a boiler full of water.
I can just picture the vapor that condenses and cools on the inside of the pipe, running down and dripping off the thermowell and cooling it also.

I've taken to mounting the temp probe horizontally, with out a thermowell, so it's in direct contact with the vapor and I still don't trust it. My preference is to use boiler temp for guestimating

[GNBrews]

A suggestion from someone who has also "Been down that road before"
Don't trust the thermometer until it accurately reads the vapor temp from a boiler full of water.
I can just picture the vapor that condenses and cools on the inside of the pipe, running down and dripping off the thermowell and cooling it also.

I've taken to mounting the temp probe horizontally, with out a thermowell, so it's in direct contact with the vapor and I still don't trust it. My preference is to use boiler temp for guestimating

That's great advice; thank you! My probe just has the thermowell that came crimped onto the cable for waterproofing. It goes into a gland fitting on the elbow with some o-rings sealing it, so it's as much "naked" in the vapor as the design allows.

Regarding boiler temp: Do you have a probe into the boiler liquid, or in the vapor space?

[shadylane]

The thermowell inters from the top of the boiler and extends downwards into the liquid.
It's long enough to reach near the the bottom of the boiler
And insulated both thermally and electrically from the SS skin of the boiler.
When the thermowell is in contact with the liquid it acts like a battery and generates a low voltage.
This voltage is used by a safety circuit to shut off the heaters in the event the boiler level gets too low

On a side note.
Most folks wouldn't believe how stratified the temp is when a still first starts to boil
Above the heating element, the liquid can be boiling hot and making vapor.
While the liquid at the bottom of the boiler is many degrees cooler.

[NZChris]

On a side note.
Most folks wouldn't believe how stratified the temp is when a still first starts to boil
Above the heating element, the liquid can be boiling hot and making vapor.
While the liquid at the bottom of the boiler is many degrees cooler.

I believe it. That's the reason why I can only barely squeeze my fingers under my bottom element in my thirty odd year old still, plus why I don't use aquarium heaters in fermenters.

[Andrew_90]

I believe it. That's the reason why I can only barely squeeze my fingers under my bottom element in my thirty odd year old still, plus why I don't use aquarium heaters in fermenters.

Do you use heating at all?

[NZChris]

I believe it. That's the reason why I can only barely squeeze my fingers under my bottom element in my thirty odd year old still, plus why I don't use aquarium heaters in fermenters.

Do you use heating at all?

There is always something in my shed that has an element connected to a controller.