Gravity - what to believe???

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drjim
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Gravity - what to believe???

Post by drjim » Wed May 12, 2021 10:34 pm

So I've gone from a couple of kits to a 3 vessel system in three months. Making all grain bitter and pulling through a hand pump, have 5 gas lines available alongside the handful in the bar shed, plus two on the mobile bar. Currently have stout cider, California common and bitter available. Imperial stout finishing off and made a bitter and a slightly mad orange Belgian IPA today (may be 8%). But that's now the problem.

When I started, my original hydrometer read sensible numbers at both ends of fermentation. It started reading strangely high at the end after a few batches, 1.012 rather than the 1.008 I had seen before with same recipe etc, so I bought another, plus a cheap refractometer.

I now have a situation where I have different readings all over!

Hydrometers read same in water at 1.000

The original one reads about 6 points higher than the new one at end of ferment, which fits with what I am expecting around 1.006. However the top reading on the newer one is low for my original gravity, and sometimes the refractometer matches the original hydrometer at the start of a brew, but it doesn't seem to like anything in between 1040 and pure water.

Beer tastes nice either way, but I want to do the sums/science properly. Is there a recommended hydrometer/refractometer brand that is actually calibrated properly, or is it pot luck???

Any ideas?

Thanks

Jim

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Eric
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Re: Gravity - what to believe???

Post by Eric » Wed May 12, 2021 11:07 pm

When you get a good hydrometer, pack it safely away. Buy and use cheap ones that, when out of the heat of the brewing day, can be compared with you sacred piece of equipment.

A refractometer is the device for the busy brewer. Mine was a cheap one and it works perfectly as long as it is kept at a constant temperature, the same as it was when calibrated. They do not provide suitable readings once fermentation begins and alcohol is present, but with experience it is possible to determine the progress of fermentation.

I take and keep samples of boiled wort and beer at racking for accurate measurement by hydrometer and recording.
Without patience, life becomes difficult and the sooner it's finished, the better.

drjim
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Re: Gravity - what to believe???

Post by drjim » Wed May 12, 2021 11:15 pm

I was thinking I should make up some sugar solutions and compare the various devices with a known gravity. Just seems odd that they all seem to work properly at some point in the scale!

I'm using no 1 readings for start and no 2 for end. So goes from 1042 to 1006. Telling my Wife that it's the other way round so 1036 to 1012!

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Jocky
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Re: Gravity - what to believe???

Post by Jocky » Thu May 13, 2021 2:42 am

Make up a sugar solution and see which one is closer.

I found very much the same between different hydrometers too, although the two Alla brand ones I compared were further out than the two Stevenson Reeves one I now have.
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Re: Gravity - what to believe???

Post by guypettigrew » Thu May 13, 2021 7:47 am

If you fancy something a bit more 'techy' you could get one of these or anything similar which measures in the right range.

I rarely use my hydrometer or optical refractometer these days. The digital refractometer I have is the MA884. Couldn't easily find one when I did a quick search just now.

Using an online calculator such as this one allows you to convert the Brix reading to SG, and also allows you calculate SG during fermentation.

Guy

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MashBag
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Re: Gravity - what to believe???

Post by MashBag » Thu May 13, 2021 8:13 am

+1 I use an optical refractometer. Easier, quicker and much less fragile.

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Cobnut
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Re: Gravity - what to believe???

Post by Cobnut » Thu May 13, 2021 8:48 am

MashBag wrote:
Thu May 13, 2021 8:13 am
+1 I use an optical refractometer. Easier, quicker and much less fragile.
I dropped my refractometer and damaged the cover. It still worked until I foolishly dropped it into the kettle which resulted in the plastic cover warping and rendering it utterly useless!

I'm taking a bit more care with my new one :D

Hydrometers (and glass hydrometer sample jars) are very fragile and as many of us brew in our garages with concrete floors, the risk of a breakage remains high! [-o<
Fermenting: Sunshine Marmalade
Conditioning: Festbier, Helles Bock
Drinking: Smoky, lager beer, Irish Export Stout, Hazelweiss 2023:2, Cascade APA (homegrown hops), Orval clone, Impy stout, Duvel clone, Conestoga (American Barley wine)
Planning: Kozel dark (ish), Simmonds Bitter, and more!

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Re: Gravity - what to believe???

Post by WallyBrew » Thu May 13, 2021 11:04 am

Cobnut wrote:
Thu May 13, 2021 8:48 am

Hydrometers (and glass hydrometer sample jars) are very fragile and as many of us brew in our garages with concrete floors, the risk of a breakage remains high! [-o<
and the answer to that is

no idea how much they cost

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Cobnut
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Re: Gravity - what to believe???

Post by Cobnut » Thu May 13, 2021 11:57 am

I like the thinking, but I bet if you dropped it and bent it, it would knock it out of calibration.

The lesson is to be bl**dy careful with your measuring equipment!
Fermenting: Sunshine Marmalade
Conditioning: Festbier, Helles Bock
Drinking: Smoky, lager beer, Irish Export Stout, Hazelweiss 2023:2, Cascade APA (homegrown hops), Orval clone, Impy stout, Duvel clone, Conestoga (American Barley wine)
Planning: Kozel dark (ish), Simmonds Bitter, and more!

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Re: Gravity - what to believe???

Post by MashBag » Thu May 13, 2021 3:09 pm


Carnot
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Re: Gravity - what to believe???

Post by Carnot » Thu May 13, 2021 10:08 pm

I would suggest that you look at the Stevenson Reeves catalogue. They are the only source I have found that produce HMCE approved hydrometers. They have a whole range of beer, wine and spirit hydrometers- at various prices and guarantees of accuarcy.

https://www.stevenson-reeves.co.uk/reev ... alogue.pdf

Refractomers are indicative at best as they are normally calibrated against a glucose solution. Once alochol is being produced then things get interesting as the alcohol is significantly less desnse than water (about 0.79). A refractomer is useful for monitoring the progress of fermentation, not necessarily accurate at determining the final density. If you desire a handheld digital variety then Bellingham & Stanley make suitable units.

https://www.bellinghamandstanley.com/en ... ractometer

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Re: Gravity - what to believe???

Post by MashBag » Fri May 14, 2021 8:12 am

not necessarily accurate at determining the final density
Yes indeed.. Not for final gravity.

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Re: Gravity - what to believe???

Post by guypettigrew » Fri May 14, 2021 8:20 am

MashBag wrote:
Fri May 14, 2021 8:12 am
not necessarily accurate at determining the final density
Yes indeed.. Not for final gravity.
So the online calculators designed to work out the gravity during and at the end of fermentation are no good?

Guy

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Re: Gravity - what to believe???

Post by WallyBrew » Fri May 14, 2021 8:58 am

guypettigrew wrote:
Fri May 14, 2021 8:20 am
MashBag wrote:
Fri May 14, 2021 8:12 am
not necessarily accurate at determining the final density
Yes indeed.. Not for final gravity.
So the online calculators designed to work out the gravity during and at the end of fermentation are no good?

Guy
Have a read of the following 2 articles and with a bit of faffing around and working out the relationship between a Zeiss and bog standard refractive index and converting your brix back to refractive index you should be able to come up with your own equations :D

https://onlinelibrary.wiley.com/doi/epd ... .tb03792.x

https://onlinelibrary.wiley.com/doi/epd ... .tb04068.x

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