Weight of a wash?

Production methods from starch to sugars.

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pommie
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Weight of a wash?

Post by pommie »

I've searched but can't find anything about this. Does the weight of a wash change as the fermentation process progresses? The S.G. goes down but does the volume increase and therefore the weight stays the same? Is there a way to calculate the amount of CO2 produced per mL of alcohol? I'm trying to work out someway to automatically determine how far along a wash is. Any suggestions?
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Deplorable
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Re: Weight of a wash?

Post by Deplorable »

Why not just taste it and automatically know how far along it is?
If it's still sweet, it ain't done.
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still_stirrin
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Re: Weight of a wash?

Post by still_stirrin »

Great question.

Let’s talk about the science of fermentation. When the ferment starts, you have an opening (original) specific gravity, OG, which is the measurement of the density relative to water, H2O. The ratio is above unity (1.000), so the weight of the wash is greater than an equal volume of water. OK, so you knew this.

But, as the wash ferments, sugars are converted to other products, including alcohol and CO2. The alcohol is less dense than water, so the measurement will naturally fall to unity (1.000), or even slightly below unity.

And since the weight of the wash is equal to the density times the volume, you could calculate the weight from the measured density and the volume, if you could measure that accurate enough. You could do this “dynamically” through the ferment and have an analytic calculation of the weight. Or, you could put it on a scale and weigh it, ferment and fermenter together.

What you’d learn is that the weight does indeed reduce throughout the ferment. And the volume of the ferment reduces too as sugars are being reduced and CO2 is expiring. The result is that the liquid level always falls slightly in the fermenter. If you mark the level at the beginning of the ferment, you can verify this behavior.

Now, the real question, for you, is WHY? It is easy to monitor ferment progress by its activity. And after you’ve done a lot of ferments (I’ve done hundreds of many sizes and types in different vessels), it is quite easy to see when a ferment is finished. Until then, it’s best to let the yeast work (in the appropriately controlled environment). Monitoring a ferment with automation is excessively anal. Even the pros in the industry just let the yeast work, although they do maintain the conditions.

Good luck with your adventure. But, if you must monitor progress, then a good hydrometer is the tool to have.
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jonnys_spirit
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Re: Weight of a wash?

Post by jonnys_spirit »

There are digital hydrometers i’m sure. Agree with the others and monitor environment as well as gravity and pH depending on what you’re fermenting. No big hurry - Give it a week and rack to glass, top up, airlock and clear for another week or three. It’ll finish.

If you’re on a tight schedule and want to produce a bunch quickly use slightly lower gravities maybe and ferment three or four days in controlled maybe slightly elevated temp then run it and start another. Everything will go faster with a bit lower sg and you just collect low wines till you have a boiler full and run those. Lower sg will probably make better likker too!

Cheers!
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Re: Weight of a wash?

Post by Saltbush Bill »

Deplorable wrote: Thu Jun 24, 2021 8:14 pm Why not just taste it and automatically know how far along it is?
If it's still sweet, it ain't done.
Why do something the simple way when you can make it far more complicated than it need be.
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Re: Weight of a wash?

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Chuck in an ispindle love them
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NZChris
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Re: Weight of a wash?

Post by NZChris »

If you happen to have a set of platform scales the fermenter can sit on, watching the weight should be just as useful as any of the other methods we use. As the ferment slows, the weight loss will slow, then stop, at the same time the SG drop slows and stops, except you don't have to take the lid off, or get a sample to test it.

I don't know how good my calculation is, so don't go spreading it as Gospel Truth, but it might drop 459g per 1kg of sucrose. I don't have scales large enough for any of my fermenters, so I haven't tested that in my shed.
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Re: Weight of a wash?

Post by shadylane »

pommie wrote: Thu Jun 24, 2021 6:44 pm Does the weight of a wash change as the fermentation process progresses?
I'm trying to work out someway to automatically determine how far along a wash is. Any suggestions?
Here's an example.
At the beginning of fermentation, there's enough sugar added to the water to make it weigh 1.070 times more.
As fermentation progresses and the yeast consumes the sugar, the weight will slowly decrease.
The weight will also decrease because the alcohol produced is lighter than water.
Because of these, the final specific gravity may be less than 1.000
Possibly as low as .990

The simplest and cheapest tool for measuring this is a hydrometer.
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Re: Weight of a wash?

Post by pommie »

A little more background information. I live in Australia and 6 months ago a wash took 4 days to complete, now (winter) it's taking nearly 2 weeks - average temperature ~15°C. I'm building an enclosure to keep it warm (probably ~30°C) and because of this access will be difficult and time consuming. My wash is 30L and in a Stainless Steel fermenter total weight ~34kg. Monitoring it externally will make this much easier. It may be that once it's up to temperature, it'll be back to 4 days completion and I can forget monitoring. Any thoughts on the ideal temperature too?
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Re: Weight of a wash?

Post by Distillusioned »

It's heavier if it's in the basement and I need to bring it upstairs to distill it. :P
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Saltbush Bill
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Re: Weight of a wash?

Post by Saltbush Bill »

pommie wrote: Fri Jun 25, 2021 2:49 pm Any thoughts on the ideal temperature too?
That will depend on what type of yeast you use.
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still_stirrin
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Re: Weight of a wash?

Post by still_stirrin »

pommie wrote: Fri Jun 25, 2021 2:49 pm A little more background information. I live in Australia and 6 months ago a wash took 4 days to complete, now (winter) it's taking nearly 2 weeks - average temperature ~15°C. I'm building an enclosure to keep it warm (probably ~30°C) and because of this access will be difficult and time consuming. My wash is 30L and in a Stainless Steel fermenter total weight ~34kg. Monitoring it externally will make this much easier. It may be that once it's up to temperature, it'll be back to 4 days completion and I can forget monitoring.
So…..it takes longer to finish in the cold weather? Imagine that!

If you tend to the conditions: proper pH, ferment ambient temperature, healthy yeast strain, proper oxygenation at the start, etc., then you’ll get consistent fermentations and ferment durations. This isn’t “rocket science”…..it’s brewing science!
pommie wrote: Fri Jun 25, 2021 2:49 pm Any thoughts on the ideal temperature too?
Uhhhhhh….depends on the yeast strain. All yeasts have an optimum ferment temperature range, so your question is like, “how long is a piece of string?”
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NZChris
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Re: Weight of a wash?

Post by NZChris »

pommie wrote: Fri Jun 25, 2021 2:49 pm A little more background information. I live in Australia and 6 months ago a wash took 4 days to complete, now (winter) it's taking nearly 2 weeks - average temperature ~15°C. I'm building an enclosure to keep it warm (probably ~30°C) and because of this access will be difficult and time consuming. My wash is 30L and in a Stainless Steel fermenter total weight ~34kg. Monitoring it externally will make this much easier. It may be that once it's up to temperature, it'll be back to 4 days completion and I can forget monitoring. Any thoughts on the ideal temperature too?
Insulate it, heat it, cool it, whatever it takes, to keep the temperature around whatever the yeast supplier recommends on the bag, or on their website.
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Re: Weight of a wash?

Post by The Baker »

A couple of my rellies use pre-loved working refrigerators as fermentation cupboards.
Commercial ones would be good, for their size.
They install 'fine temperature' controllers, and a little heater.

Excellent.

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Ben
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Re: Weight of a wash?

Post by Ben »

Google fermentation chamber, there are a bunch of ways to set them up. Essentially what you need is a large insulated box, a heat source and a cooling source then you have control of that variable.

If you are using a stainless fermenter does it have a take of port? If not you could get one welded in, if you have a rotatable racking arm and a valve you can take off what you need to fill your hydrometer flask, or what you need for a refractometer without disturbing the ferment.
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