Al The Chemist

@SlickFloss I might need to update my proccess! Seems like you're doing something right.

@Silk City Distillers, have you had any luck with esterification on a played setup? I’ve hit some walls trying that. Wonder if there's somrething I'm missing in the proccess.

The copper state is an interesting one. It could be a catch 22. Not neutralizing the sulfuric acid is an upside. Though not neutralizing the sulfides is going to be a problem. The sulfites are not a major issue as they are very volatile and exposing the distillate to air for a while should get rid of them. Though the rotten egg sulfides are quite heavy. The heat and alcohol content on the plates should provide a good platform for esterification. Though the time parameter could be a challenge. Even in favorable conditions, most documentation recommends a minimum 24 hours for esterification. You can push the plate process with a full dephleg for a while. thumpers with a valve bypass can be super useful here. You can pre charge the thumper for esterification. Then run heads through the bypass then engage the thumper.

Stumbled onto this thread a little late. Adding sulfuric acid does help esterification, through it still depends on the water content and heat conditions. Even a relatively high gravity wash (14-17%) will still have too much water to allow for good esterification. Meanwhile if you add sulfuric acid to the wash, the acid will start interacting and create sulfites and sulfides. The sulfides (rotten egg smell and the likes) can be absorbed and filtered out by a reaction with copper, though the sulfites (burned matches) do not react with copper. So too much, or too long on the sulfuric acid during fermentation or in the wash at any point can be an issue. Adding sulfuric to low/high wines will work better to promote esterification. Though I wouldn’t drink that product, I’d redistill it. Using sulfuric acid as a stabilizer in a final product sounds a bit suspect to me. It’s a very strong acid and I would avoid drinking it at any concentration.

Great tip. I had no idea.

Understood, thank you!

Got it, so you get a full “pelicose" layer forming on that dunder? Considering fruit don’t really carry their more traditional flavors over fermentation and distillation, did you find any that help the more banana, butter scotch, caramel, vanilla, side of things? I figured Bananas would be an obvious one, but wondering if there is something more interesting and adventurous there. I’m personally trying to aim for something rich and heavy, less light fruity. With hopefully a touch of light acid on the pallet (along the lines of pine apple) to balance things out a bit. Hope I'm not beign overly specific here

Thanks for the info everyone. I’ll keep my fermentations closed. If you’re open to share, I’d love to hear more about the “flavored dunder”. The backset I store is essentially sterile, do you rely on natural bacteria and yeast for the fruit itself to kick up the process? @adamOVD the CO2 tip is interesting, I haven’t considered that. I’ll definitely give degassing a go before fermenting. As for heating. I have heat elements operated by an inkbird to keep the wash at the ideal temperature for the yeast. My rum fermentations tend to go pretty strong. I pushed the SG on this latest one a bit high, though so far so good.

Hey folks, I’m on a mission to make a rum that doesn’t just have hints of funk and fruit, but has those flavors clear and present. I’ve managed to get a fair grasp of “synthetic acidification” for the wash, though I’m feeling like I’m missing some of the organic chaos in the process. I’ve heard a lot of talk about open fermentation for whisky. And from the conversations here about Ph crashing in rum I can only gather some people are getting bacterial infections from open fermentation. Though I haven’t heard any open discussions on this (at least none that I could find). I’m used to fermenting covered, sanitized and locked. Anyone interested to talk a bit about their experiences with open fermentation for rum? Specifically for the wild organism factor. Cheers!

Makes sense, thanks!

I've heard mention of people charging a thumper with backset combined with deep tails. Seems to me like that will not have enough alcohol content to do the trick in the thumper. I guess the idea was to try and “infuse” more flavor into a rum. Was curious to hear your thoughts.

@Kindred Spirits, I'm looking into commissioning a single vertical thumper for a small scale test. I am worried about the stability of a double retort stack on a small scale. Curious what you guys think about a plate, then thumper? So essentially a plate to strip and a thumper to redistill and infuse. Footprint is exactly the issue I'm trying to resolve.

Thanks @Bolverk

Jumping in 4 years late on this one. @DrDistillation, as to your comment of thumpers falling out of favor with the advent of bubble plats. If you are going purely for a higher ABV off the bat I’d agree there. Though for things like Rum for instance, where you want a secondary reaction chamber for esterification with a lower water content. Or any other flavor infusion phase that is not botanical, I really can’t find any other solution besides a thumper. Would be curious to hear more of your thoughts on this. I’ve tried many different types of still configuration for Rum (without a thumper) and have found that even multiple pot distillation is not amazing. The plates separate the esters too far into heads and tails and most of the ester have an evaporation temp either above or below ethanol. @JustAndy, do you have any additional information about the pressure buildups for different amount and height of fluids? I am looking into building a vertical thumper for a 3kw 10gal boiler and I don’t want to scale things wrong and over pressurize.

A bypass valve above and below the thumper is part of the planned design. I'll see what I can pull off.

Tested my cuts. Conclusions. Does a “synthetic dunder” (IE: deep tails + Backset + controlled acids) work? Yes, 100% it does. The next experiment will likely be a vertical thumper setup, as the distillation method seems to be the obvious next issue. Heads: - Really nice, strong tropical fruit, coconut and pineapple, nice and fresh high notes on both the nose and pallet. Though far too headsy to blend. Hearts: - Almost clean and neutral. A bare hint of pineapple, though (in my taste) not enough to distinguish it between a vodka and a Caribbean rum. Maybe more reminiscent of a cachaça. Early tails: - Really nice deep funky aromas, molasses and moldy cheese but has that tailsy “burnt iron” finish. Wondering if cask aging will remedy that over time. Deep tails: - Explosive foot fungus and heavy cream, way to tailsy to consider blending. (went into dunder) Would have loved to get the heads and tails esters appear in the hearts. Considering the evaporation temperature of these esters and the distillation method used, I guess this is not surprising.

Awesome, thanks!

Excellent info. Thank you. Can you explain more to what you mean about the "1.5"? Is that ABV of tumper as it related to the boiler? A 1 gallon thumper is very manageable for a smaller dedicated still. At that size even 2 should stack pretty well. I've heard some conversation discussing the thumper being 50% of boiler. Seems excessive.

Interesting. Appreciate the info. For me, it would be mostly for single runs. I might get by with one. Would you think it be functional to load the acids into the thumper instead of the boiler? This would resolve the dunder issue. I might start pursuing a vertical thumper again.

Yup, from what I'm reading, thats essentially the same design I had in mind. @Bolverk, what are your thoughts on using 1 vs 2 thumpers?

I'm psyched to hear this has been discussed. I've wanted to have one made for a few years now. Thank you for the new rabbit hole!

Yeah, the issue might be the Panela. Fermentation went off without a hitch. 1.098 to 0.997 in 8 days. My concern about this process though is its effect on the dunder. My dudner is now acid loaded (the butyric is definitely still in there). So unless you start this process fresh every time, there will always be the issue of acid transfer through added dunder. At that point it will be hard to judge how much there is of what in there. The more I tinker with Rum the more I’m getting the feeling that a thumper is the way to go. I initially thought the plates would do the same general job if all the source material is already in the boiler, but that does not seem to be the case. I did get some strong esterification to make a spirit with a very distinct flavor. But I would by no means say that It’s so strong I can use it as a flavor blender for “softer” Rums. A traditional thumper (sitting on the side) would be tricky for me to adopt considering how I have things configured. I’ve been playing with a design for a thumper that sits vertically on a column stack. I haven’t seen anything like that commercially available, which makes me think there is something about a thumper that I just don’t understand, or this would be more widely available. Maybe sonething to do with the more direct heat transfer? I’d be curious to hear your thoughts. The way I see it, It can be a single “over gown”, tall, single bubbler setup, encased in a Xgallon container, with a port to charge it and a valve to clear it. Maybe an overflow line that at a specific charge height funnels the liquid back to the stack under it.

OK! So as I mentioned above, this method is 100% functional. At the end of the day, it boils down to what flavor profile you are looking for in your Rum, add the acids that create the esters you are looking for. No need to roll the dice with an open, infected fermentation that contains an unknown amount of unknown bacteria (though it does take some of the magic away ). Take aways: 1. The Rum overall came out far too light for my liking (just a hair above neutral). After reading some old notes and doing some research I actually went for a 3 (1/2) phase reflux. From the boiler up; Plate, Helmet, Plate, Dephleg, Condenser. This was also my first time using just Panela for my fermentation. Conclusion: Will try a; plate, helmet, dephleg, configuration next time. Hopefully this results in a slightly heavier product. first pate traps the initial stripping, then regulating the dephleg should churn the catalyzation in the helmet. I will also go back to either full Molasses or a Molasses Panela mix. 2. There is no need to add the acids during fermentation. All it results in is a potential for a mess and severe stink (if you use Butyric). The fermentation does not contain nearly the right conditions to start any form of serious esterification. The acidity is not low enough and the water levels are too high. I also think I might have not added enough sulfuric acid. conclusion: Add acids directly to the charged boiler. Even if you do add Sulfuric acid I don't think letting it sit will help any as the water levels are still too high. I added 1.5ml per gallon of sulfuric, I'd try 3ml per gallon next time. 3. A little Butyric acid goes a LONG way. Conclusion: I would aim for something around 6ml per gallon (I ended up with 12ml per gallon). Once the cuts rest a bit and my nose rests, I have a feeling I will get some serious ripe cheese funk in this rum (which is not all bad). 4. Ethyl-Butyrate is quite tricky to capture. I lost a bunch of it in the foreshots and it vanished almost immediately when I took a distillate sample to test for cuts. This might go back to not using enough Sulfuric acid and not forming as much Ethyl-Butyrate as I'd hoped. 5. The dephleg is super useful. At first I considered just letting everything run free, though the Dephleg really helped me balance the collection, especially as the hearts started going into the tails. That border between the 2 is where I found most of the heavier Rum notes I was looking for. I am still looking forward to going though these cuts and seeing what I came up with. Cheers, and thank you for all the feedback along the way!

Finishing up the run as we speak. Collecting tails. going to stop collecting at 10-15%, then combine it back with backset. Long Story short. It worked! Esters came out essentially in the order I expected. First cocoanut and candied pineapple, then deeper funky cheese notes. All the while a good buttery layer that really shined through as clear butterscotch in one of the cuts (I added 3ml per gallon of Lactic acid before running). Now that I have the general idea of how this works. There are things I would do differently. I'll post a more detailed reply shortly.

Yup. Exactly what I’m thinking.