Adjusting pH of a Rum wash (All Molasses)

[Yummyrum]

I’ve mentioned several times about the pointless need to add shells or Calcium Carbonate to a Molasses wash during fermentation .
I’m not anal about keeping records but I have noticed that usually my washes start around pH 5.5 and finish around 5.0

I’ve mentioned that adding shells or Calcium Carbonate is a waste of time . I’ve also said that Calcium Hydroxide was a better option iff’n raising pH was the goal . Now that was based on stuff I did about 7-8 years ago and I might not have remembered it well .

Well I thought I better put money where mouth is and see for sure .

So I made up a small 3litre wash of Salty’s all molasses Rum .

Poured it into several jars (400mls each)

To the first , 1 teaspoon of Calcium Carbonate
To the 2nd , 5 teaspoons of Calcium Carbonate … about 42grams
To the 3rd , 1 teaspoon of Calcium Hydroxide ( mixed with a bit of water to a slurry )
To the 4th , 5 teaspoons of Calcium Hydroxide … about 15 grams ( mixed with a bit of water to a slurry)
To the 5th ,1 teaspoon of Sodium Hydroxide (Caustic soda)
To the 6th ,5 teaspoons of Sodium Hydroxide …about 33 grams ( Caustic soda)

Jar 7 , the original wash as a standard .

Calcium Carbonate

Calcium Hydroxide

Sodium Hydroxide

I added the bases and stirred them well .
After about a few minutes , I measured the pH

Reference .5.5
1T CaCO3 …. 5.5
5T CaCO3……5.6
1T Ca OH ….5.7
5T CaOH …. 5.9
1T NaOH…. 10.0
5T NaOH …..12.1

After about 10 min seems the that that both the Calcium Carbonate and the Calcium Hydroxide had settled to the bottom of the jars and bugger all reaction taking place .
Not suprised about the Calcium Hydroxide , it has a very low solubility . IE , it doesn’t dissolve very well in water and wants to sink to the bottom .

The Sodium Hydroxide on the other hand smashed it out iff’n instant pH adjustment is the desire , this is bullshit fast and powerful stuff .

I did this test on 400ml sample

So say’n you are doing a 23 litre wash scaling it up ,
Thats 57.5 times more .
So 5 teaspoons in 400mls equates to 2.4kg of Calcium Carbonate in 23 litres …. To raise an all Molasses wash by 0.1pH …. quite a lot to achieve SFA

5 teaspoons of Calcium Hydroxide equates to 0.862kg to raise the pH by 0.4 … again , a lot of lime for bugger all change .

So I guess , thats what I’m talking about . A fuck ton of Calcium Hydroxide and a Mega fuckton of Calcium Carbonate to make bugger all difference to an all molasses wash .

The Sodium Hydroxide , on the other hand does it well . To be honest , why better than I expected . So maybe thats worth looking into further .

Anyway , going to wait overnight and see if time helps the Calciums do their thing.

[Demy]

Very interesting, I'm following with interest... thanks for taking the time. So far I understand that for a certain amount caustic soda is the winner right?

[Bolverk]

Yummy, great post! these results echo what I have found as well.

When I started playing with high dunder and acids I was advised by a pro to use lye over lime to make bigger adjustments faster.

I can't tell you how many times I over shot my desired pH because the lye is so effective. I've found a a good way is to use them is a combination of lye and lime. The lye to bring you close to your desired pH and the lime to get you dialed in.

[subbrew]

Nice work, love the science. That said I have always thought of calcium carbonate as a buffer to prevent a crash rather than an agent to really move the PH. Since a PH of 5.0 is still rather neutral I would not expect much reaction. But as the ph falls toward 4.0 I would expect the reaction to pick up. (for those that might no remember, the ph scale is logarithmic, so 4.0 is 10 times as acidic as 5.0.)

I would be interested in how much acid you could add to the 1 tsp calcium carbonate sample, either citric or lactic would work, before it got to a ph of 3.5?

Well done on showing how good sodium hydroxide is if you want to really move the ph. And how poor calcium calcium carbonate is. Right tool for the job.

[bilgriss]

I'll add the obligatory disclaimer that if working with sodium hydroxide, you need to exercise the proper degree of care. It is very caustic and can have very violent reactions if used improperly.

[MooseMan]

I'll add the obligatory disclaimer that if working with sodium hydroxide, you need to exercise the proper degree of care. It is very caustic and can have very violent reactions if used improperly.

Glad you did bilgriss.

I work with NaOH almost daily and it's a crazy strong base.
Don't ever use it without skin and eye protection.
Example of how strong a base it is, 8kg will take a 500l tank of water over pH 13 and needs many thousands of litres of water to flush back to neutral.
It's also exothermic when mixed into fluids. Sometimes violently as bilgriss hinted.

[Yummyrum]

.
It's also exothermic when mixed into fluids. Sometimes violently as bilgriss hinted.

Sure is , in fact I forgot to mention that as I stirred in that 5 teaspoons , the jar did get warm .
Yes I also should have mentioned PPE too . I’m a Lab tech so should have known better .

So over night the samples look like this .

Again I recalibrated the meter .
But wait , this morning all the readings are out .Maybe the temp was different yesterday and it had screwed the meter readings . 5.5 yesterday is 5.2 today .
Maybe its because I have a cheapish pH meter that only calibrates at pH 7 instead if a pro one that has three point calibration .

Ref ……………5.2
1t CaCO3…..5.2
5t CaCO3……5.3
1t CaOH…….5.5
5t CaOH…...5.9

So I stirred them all to see if something had been happening down the bottom .

Ref ……………5.2
1t CaCO3…..5.3
5t CaCO3……5.4
1t CaOH…….5.8
5t CaOH…...6.6

Ahhhh…. So the Calcium Hydroxide had been doing something although very slowly and there was still a lot on the bottom .

Now one things for sure , even when calibrated , a pH meter will give different readings from day to day .

[Yummyrum]

As I mentioned , the whole purpose of this test was to show how hard it is to adjust the pH of a Rum wash .
So without a comparision to a sugar wash , it probably means nothing .

So I made up a simple sugar solution .
To keep it relevant , I adjusted the pH using Citric acid from 7.2 ( my municipal water supply) down to 5.5 ( so it’s the same pH as the Molasses wash) ...it took bugger all Citric acid , maybe about the size of a grain of rice or two worth in my 3 litre solution.
So now we have the same pH as the molasses wash was that I tested yesterday . You would expect that the results will be the same .It should be shouldn't it ? pH is pH .

He's the Jars .Same method as yesterday and pH taken at same time after strirring and settling .

Well there was no mucking about .Even the Calcium carbonate got straight on the job .
Ref jar.........5.5
1t CaCO3......6.8
5t CaCO3......7.4
1t CaOH.......8.0
5t CaOH.......8.4

It is clear that it is very easy to adjust the pH of a Sugar wash and extremely difficult to adjust an All Molasses wash .Even though the pH of both is the same , the Molasses has a significant buffering effect so much more powerful than Calcium Carbonate and even Calcium Hydroxide which is a pretty strong Base in it's own right has a hard job budging it even when excessively large amounts are used .

I'm going to let these sit and see how high the pH will rise .
One thing's for sure . Calcium Carbonate does not hold the pH at anything near 5 in a sugar wash . It keeps reacting and it will go much higher .Obviously one needs to be aware how much is added .Excessive amounts will deplete the available acid and keep raising the pH ....not something you want to happen if you want to leave a wash for any period of time before distilling .Hense the recomendation to remove bags of shells as soon as fermentation is over.

[MooseMan]

Thanks for going to so much effort on this Yummy, it's fantastic info for those interested, and great research fodder for people trying to gain an understanding of this area of the hobby.

Clearly the molasses has been so saturated with buffer (acid:base:acid:base) that it takes a great deal more of either to push past the buffer, before the pH changes.

As you said at the very beginning, adding an alkaline source to Molly washes is basically a waste of time as it's so well buffered already the pH will never go too low during ferment.

As I mentioned, at work we dose 8kgs of sodium hydroxide to a 500l product tank for viral inactivation, then when it's time for the next step in the operation several days later, we have to acidify it.
It takes literally gallons of glacial acetic acid (Scary stuff) to get it below pH 3. Without the prior addition of NaOH it would be a couple of litres.

[Yummyrum]

Thanks moose . It sure is an interesting thing . The more you add acids and bases , the more you need of the other to swing it the other way . You’d think if one cancels /neutralises out the other then you’d be back to as if nothing had changed … but thats not the case .

BTW , your job sounds intriguing .

[Yummyrum]

I would be interested in how much acid you could add to the 1 tsp calcium carbonate sample, either citric or lactic would work, before it got to a ph of 3.5?

Thanks subbrew
I will get onto that tomorrow .
I think I know where you are going with this .
I’m also curious to compare that to the reference jar .
Either way , I’m figuring there is gonna be a lot of acid used .
Wish I had access to some concentrated Sulphuric , I think it might be more useful .

[MooseMan]

Thanks moose
BTW , your job sounds intriguing .

It's a very interesting job that's for sure. Probably the strangest one I've ever had, and I've worked in some pretty varied industries!

I'd love to share more about it on here but it's so niche that pretty much any details I give would make it quite possible to identify me.