Hydrometers and Rum.

[Nutmegmooner]

Does a hydrometer work well with a Rum wash? I'm thinking the inherent viscosity of molasses might throw it out of whack. My ferment went from 1.065 to 1.025 in about a week and certainly tastes done, but the calc says that's only 5.16% . I don't want to push the limits of the upper end as I understand that can give some off flavors but my end result seems a tad low and would like to bump that up a little, say around 10%. I'm using baker's yeast in an effort to keep things simple. Hell, that's why I'm still stuck on Rum! More sweet next time? Help, please!
Thanks

[NZChris]

Molasses is full of all sorts of goodies that your hydrometer is reading as well as the fermentable sugar.

It sounds like your ferment is finished. Don't overfill your still.
if you want to have no puking, leave the still head off until until it froths to the top, then use a mister to spray the foam back down. It should be ok after that unless you use too much heat.

[ga flatwoods]

Nutmeg it needs to be clean liquid to get a good measurement especially in the beginning. It is easier to get that near the end of fermentation. Has the ferment got cold or is the temperature what it needs to be. It should go dry to 1.000 slightly more or less. Try to get some clean mash even if filtered for your final reading. Has the head dropped and clearing began? It can sit a little while longer if it has not.
Ga Flatwoods

edit typed along with Chris. +1 on his comments also.

[woodstock]

I find that the molasses, depending on how much you use per gallon of water, does throw off the hydro readings. I never seem to get a wash to quit at 1.0 or less, but my wash usually seems done. (And my hydro is usually broke and in the mail, darned thing) . When the bubbles stop... Or almost stop, and the wash is clearing to your satisfaction... Go with it. Let it sit a little longer if u can. And like chris says... Don't overfill. My thought is that running a little early isn't such a bad thing.

[Jacksonbrown]

I just made up a mix of 4 parts water to 1 molasses by volume. I think it ended up at 1090. What ABV can I expect?
I wanted 8% to 10%, so what SG should I have aimed for?

Edit, I should add it was blackstrap with no added sugar and ph adjusted. Ale yeast went in and it's holding at 25 degrees.

[casamayor]

Hello,
With pure molasse the final gravity is around 1040, if you add sugar you could expect around 1020
CM

[RockinRockies]

I began at 14% abv on a 50 gallon ferment. Ended up at 2% and now it's developing a slight white film.. Not sure yet but likely to run it tomorrow.

Still slightly sweet but I'm concerned about infection. Maybe I'll add more DAP? It's in my service room so it's warm

[Yummyrum]

What were the start and finish readings on the hydrometer? As you have probably figured out in this topic , Molasses will skew the readings from what you would expect from a beer or sugar wash .

What recipe did you use ?

Ive not had a Rum fermentation grow a mould in nearly 10 years . Whisky , yup , nearly everytime .

But at the end of the day , if I was in your shoes , I’s run it now .

[hawkwing]

I did up a Rum recipe in BeerSmith. What I did was add the Molasses as two separate items. My Blackstrap molasses that I used in the past was from a bulk foods store. It was 37% sugar according to the nutrition label. So I added fermentable molasses as 37% fermentable sugar and the rest as I fermentable sugars (63%). The SG lined up pretty good. I will have to check the FG when it’s done and see if it lines up with BeerSmith. There is probably a calculation that can be done to give an approximate FG.

[Bushman]

I find that the molasses, depending on how much you use per gallon of water, does throw off the hydro readings. I never seem to get a wash to quit at 1.0 or less, but my wash usually seems done. (And my hydro is usually broke and in the mail, darned thing) . When the bubbles stop... Or almost stop, and the wash is clearing to your satisfaction... Go with it. Let it sit a little longer if u can. And like chris says... Don't overfill. My thought is that running a little early isn't such a bad thing.

That is why when making rum I use a Refractometer.

[Demy]

I'm not a rum expert but I have a trivial question ... there are still signs of surface fermentation? If so it should still remain, the fermentation process is not based on exact times but from visual inspection / hearing and measurement.

[bluefish_dist]

Molasses has a lot of unfermentables. At 1.025 it’s done. You can start higher knowing it’s going to end higher. I usually went 1.10 or so for an opening gravity when using high amounts of molasses. 1.11 would be fine as well.

[xerolad]

I made a 1 gallon test wash with baking grade molasses with a SG of 1.089. I pitched it with Wyeast 3763 Roeselare Ale Blend at the recommended rate for beer wort. The idea was to strip it, then use the backset for another test batch, using White Star D497 Caribbean Rum yeast. I've never deliberately done a mixed fermentation before, and I guess what I'm worried about is that the yeasts will tap out before all the sugars get consumed, and the bacteria will convert an excessive amount to acids. Anyone have any insight into higher gravity molasses mixed fermentations?

[howie]

'backset' from a rum is usually called dunder.
so by a "mixed fermentation", you mean using dunder and fresh molasses in a fresh batch?

if so, i wouldn't be worried about the yeast tapping out(?).
your main worry would be the a PH crash by not adjusting the PH and not adding buffers such as oyster shell.

sorry if i misinterpreted your question, it's early here

[Yummyrum]

Ummm , All Molasses washes with Dunder never pH crash . In fact they are extremely pH stable . It’s only pissy Rum washes which are mostly Sugar with a bit of Molasses which are a problem ….. just like any other Sugar wash is likely to be.

I have Start gravity’s well over 1.120 and Final at around 1.060 .
pH usually starts around 5.5 and finishes no less than 4.5 .

[Saltbush Bill]

Agree 100% with Yummy......I've never checked or adjusted ph on a Rum wash.....even back when I did use some sugar in them. Never had one fail to finish yet.

[xerolad]

Cool. No stress!

White Labs describes their Roeselare Blend as: "Specific proportions of a Belgian style ale strain, a sherry strain, two Brettanomyces strains, a Lactobacillus culture, and a Pediococcus culture". It's a bug zoo. That's what I meant by a mixed ferm . I think the sherry strain they carry can go up to 15% abv, so all good. Does molasses contain complex carbs too, or is it mostly just simple sugars?

[howie]

thanks Sb & yummy, i didn't know that about an all molasses.
i've not done an all molasses yet, just a mol/raw sugar combo.
i had a PH problem in the early days with too much dunder.

xero - that 3763 yeast sounds interesting, let us know how it goes.

[xerolad]

Will do howie

[hawkwing]

I got around to running my rum I was talking about. The FG was 1.042. I double checked BeerSmith and my 1 US gal/3.785L/5.49kg of buck slop 100% molasses that I entered as 37% fermentable sugars and 63% non fermentable sugars turns out to be SG 1.049 with just the non fermentable part. So that’s a decent prediction considering the potential sources of error.

[Saltbush Bill]

i had a PH problem in the early days with too much dunder.

Used way to much huh ?

[Yummyrum]

i had a PH problem in the early days with too much dunder.

Used way to much huh ?

Adding “extra Dunder” kinda makes sense …. More Dunder = more Rummy flavour next time .
But no , like some things tend to be , often less is more .

Dunder is acidic… but thats not the only thing . Dunder is the accumulated boiled down concentrated unfermentable muck , wash after wash .
It has an accumulative gravity .Dunder will have a SG of around 1.065 … thats a high Start Gravity before you even add fermentables .
So it seems to work out that using no more than 10% Dunder will keep Rum washes going wash after wash

[howie]

i had a PH problem in the early days with too much dunder.

Used way to much huh ?

oh yes, i remember the rum wars of 2020, my notebook is riddled with expletives for this short period.
it was a tried & proven recipe which suggested using 10L of dunder in a 25-30L wash

[hawkwing]

i had a PH problem in the early days with too much dunder.

Used way to much huh ?

oh yes, i remember the rum wars of 2020, my notebook is riddled with expletives for this short period.
it was a tried & proven recipe which suggested using 10L of dunder in a 25-30L wash

That is still in some of the tried and true recipes. Has that been found to be too much Dunder?

[howie]

personally i think it is.
10l is about 40% of a 25l wash, i then read that about 25% is ok and i have used 5l ever since with no problems on a mol/raw sugar wash.
using the 10l, my gen 1 limped over the line, and gen 2 was a nightmare.
i have observed other newbies like me have had the same problem using 10l of dunder.
dunder can be quite low in PH, and you have to remember that the PH scale is not linear.
apparently, mixing equal parts of liquids with PH of 4.0 & 6.0 = 4.3 PH.
i did a few tests on rum washes and found the PH can drop 0.5 to 1.0 in the first 2 days as well(without good old oyster shells).

i've just found an online calculator, but it only uses water at PH 7.
so if i put in dunder at PH 4............
1) (10L @ PH 4) + (15L @ PH 7) = PH 4.398 ( a PH drop of 0.5 would be interesting)
2) (5L @ PH 4) + (20L @ PH 7) = PH 4.699 (would probably be ok)

but basically a lot of PH stress (for both the yeast and the distiller ) can be relieved through using oyster shell/chicken grit from the start.