So what I'm I doing wrong Rum wash went belly up again.

[Blackgrub79]

I don't remember where I read it but I read that you could reuse the wash from a previous distilling to help add more flavor to the wash?

I have attempted to use two gallons of old wash to make a new wash heat it up to the point that the sugar dissolved into the water. Then wait for the wash to cook down and add yeast packages as directed.

First two times I did not bring it to a boil but the third time I made the original wash in my electric still/ fermenter the everything went great on the first batch. After distilling I let it cool down and drain it and left about 2 gallon of old wash in there still hot and steming cracked up the heat to high added molasses and sugar to the still heat it up until bubbled turned the heat off let it cool to temperature yeast packages said added yeast.

It did bubble up for about 12 hours then stopped. I opened the lid and saw foam a few inches thick inside and it had that interesting smell like that last ones.

So I'm doing something wrong here! I would like to correct it I have no problems when I make the mash without the old wash in it just saves all few gallons being filtered but that better then wasting three gallons of molasses and over 30 lbs sugar.

Thanks for the advice

[BlackStrap]

2 gallons of backset to how many gallons of fresh wash?
What was the Starting Gravity?
What is the gravity now?
Is the wash in a temperature controlled environment?
Does the wash smell bad now?

Are you following any sort of proven recipe?

3 lbs of Molasses = roughly 35 lbs.
30 lbs of sugar
and 2 gallons of backset or dundar.

I'm guessing you are going to want to at least 23 gallons of water
this would roughly equal a starting gravity of 1.106

Using the backset in large quantities can drop the PH of the wash to below the yeast tolerance.
Also starting out to high of a gravity for the yeast will rupture the yeast cells this is called Osmotic shock.

There's a lot of variables to consider

[shadylane]

Using the backset in large quantities can drop the PH of the wash to below the yeast tolerance.
Also starting out to high of a gravity for the yeast will rupture the yeast cells this is called Osmotic shock.

There's a lot of variables to consider

Kinda what I was thinking.
The full recipe and some pH and gravity measurements would be nice.

[Yummyrum]

From your description , it sounds like you are fermenting and distilling in the same vessel.

It is better if you can ferment in a separate vessel , then let the yeast settle out ( a couple of days to a week) before syphoning off the fermented wash off the top of the yeast cake left in the fermenter . At this stage you either dump the yeast cake or use it for your next fermentation (as nutrients ). But don't have it in the boiler when you are distilling as it can release bad flavours as the yeast cells burst open .

It sounds like you are doing a "One and done" run . Assuming you have a Pot still , this is not the best way to Distill . Better to do a separate stripping run followed by a Spirit run .Regardless , you keep some of the stillage left in the boiler after the Stripping run . In Whiskey process , the Stillage is called Backset , however in Rum processing we call it Dunder .

You only need to keep and reuse about 10-20% of the volume of your next fermentation . When doing All molasses Rum , you would be best to limit Dunder to about 10% . So say you are fermenting 10 gals , you only need to add 1 gal of Dunder . When doing a half sugar Molasses wash Like presumably you are doing , you can add up to about 20% Dunder .
If you exceed these levels , you will have problems .

Getting back to your 12 hour fermentation .It will foam and carry on for the first 6-12 hours before slowing down to a gentler fizz. It usually takes several days to a week for a Rum to ferment . A quick test is to put you finger in it and have a taste . If it has the slightest bit of sweetness , then it is not finished .When done it should be bitter , almost salty tasting .....but don't let you brain trick you the the smell of the Molasses is making it taste sweet .

[shadylane]

Another thought, 100% molasses has enough nutrients for the yeast to finish.
But substituting a large amount of white sugar dilutes the natural molasses nutrients.
Molasses has nitrogen and magnesium that yeast needs, white sugar has none.
Molasses also can moderate pH crash, white sugar can't.

[Saltbush Bill]

I read that you could reuse the wash from a previous distilling to help add more flavor to the wash?

I have attempted to use two gallons of old wash to make a new wash heat it up to the point that the sugar dissolved into the water.

It will help a lot if you clarify what is really happening here, your using old wash, or are you using Dunder ?
There is a big difference.

[subbrew]

To add to what Saltbrush said. What is left in the still after a run of rum is called dunder. (after a whiskey distillation it is called backset) A mixture of sugars and water is a wash. It is common to continue to call it wash after fermentation although some people will call wash that has been fermented distillers beer or just beer.

If you don't have a hydrometer to measure the gravity of you wash you really need one. You can taste but this is one measurement that can really help.

[Yummyrum]

Good point Subbrew , we really should be more consistent with calling fermented washes , distillers beer or just beer . It is one of those terms that has been used in industry but we a slack on the forum .

As to Hydrometers .
I think they are a great tool , but when it comes to Rum they can be totally confusing . Molasses is at best only 50% fermentable , the rest seriously skews the Gravity readings .

Dunder is also a problem . The gravity of Dunder is significantly higher than the beer it originates from because at least 25% of the liquid is removed during distilling .

Now add that Dunder to your next wash , and you now have the density of the unfermentable stuff in the new batch of Molasses plus all the unfermentable stuff from the last batch . So the start gravity will get progressively higher and higher each successive run .

And so will the finish gravity.

Readings of say 1.070 SG and 0.995 FG which might be normal to expect on a Sugar wash will never be seen on a Rum wash that uses Molasses . .

This compounding or accumulation of unfermentable matter is the reason that Dunder needs to be limited to around 10-20% depending on the style of Rum wash you are making .

Even then , on an all molasses Rum wash you can expect a start gravity of around 1.120- 1.140 …… yes that is not a typo .
While the finish gravity can be around the 1.055- 1.060 mark .

Half sugar /Molasses washes are somewhen in between a Pure sugar wash and an all Molasses wash .

This is why we strongly recommend folk use the Tried and tested recipes on our forum before experimenting with made up ideas

[shadylane]

It did bubble up for about 12 hours then stopped. I opened the lid and saw foam a few inches thick inside and it had that interesting smell like that last ones.

There might be a problem but maybe not, without a hydrometer it will be difficult to tell.
Stick your ear to the side of the fermenter, if you hear sizzling it's still working.
Look at the surface of the wash, if it's foamy or a gazillion tiny bubbles breaking the surface then it's still working.

[Saltbush Bill]

And dont forget to taste it, is it still sweet, is it tart or sour tasting?.....dont over think things, stick to simple methods that work.
As shady said if its still working you can put an ear near the surface of the wash and listen, you will often hear what you cant see.