I have a question about the point in time that the gravity reading is done to calculate efficiency that I'm hoping someone can help me with.
From what I have read it appears as though efficiency should be calculated using the Boil Gravity (ie, the gravity of the wort just as it reaches a boil). The reasoning in Palmer's How to Brew is, "we want to think in terms of the boil gravity because that volume of wort and its gravity is our actual yield".
It's not clear to me why it has to be boiled though? Why can't the reading be done as soon as the mash is complete? Is it because the maximum extract values for each grain also assume boiling temps..and that sort of standardizes temps for both the maltster and the homebrewer, whereas mash temps could really be anywhere?
Thanks!
Post #2 made 14 years ago
Another reason is because to calculate the efficiency you need to know the volume
The volume needs to be corrected based on its temperature, by measuring the volume at start of boil, you know the temperature and thus can correctly work out the corrected volume, and thus efficiency
Its useful to have a start of boil reading and volume, and an end of boil reading and volume as a double check
The volume needs to be corrected based on its temperature, by measuring the volume at start of boil, you know the temperature and thus can correctly work out the corrected volume, and thus efficiency
Its useful to have a start of boil reading and volume, and an end of boil reading and volume as a double check
Fermenting: -
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III
5/7/12
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III
5/7/12
Post #3 made 14 years ago
Ok.. that's sort of what I was thinking as well. 100C standardizes the temp and thus the volume for both the theoretical maximums as well as the homebrewer.The volume needs to be corrected based on its temperature, by measuring the volume at start of boil, you know the temperature and thus can correctly work out the corrected volume, and thus efficiency
Thanks.
Last edited by Ralphus on 11 Jul 2011, 22:29, edited 5 times in total.
Post #4 made 14 years ago
So whats the rush?Why not take your sample after mash is done and read it later after it cools down and you're doing your bookwork?
Also,how do hydrometers know which way to turn so that you can't read the scale you want?
Also,how do hydrometers know which way to turn so that you can't read the scale you want?
AWOL
Post #5 made 14 years ago
Lylo wrote:Also,how do hydrometers know which way to turn so that you can't read the scale you want?
It's a damn mystery that has baffled me every single batch.
Last edited by BrickBrewHaus on 12 Jul 2011, 05:23, edited 5 times in total.
Post #6 made 14 years ago
That's what I doLylo wrote:So whats the rush?Why not take your sample after mash is done and read it later after it cools down and you're doing your bookwork?
Also,how do hydrometers know which way to turn so that you can't read the scale you want?
When I reach the boil, I take a sample, and measure the volume.
Wait for the sample to cool to about 40-50C and then take a gravity measurement and return the sample
At the end of the boil, i measure the volume, fill my cube for no-chill
I then take a gravity sample from the cooled trub, and measure the trub volume too.
Last edited by stux on 12 Jul 2011, 10:00, edited 5 times in total.
Fermenting: -
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III
5/7/12
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III
5/7/12
Post #7 made 14 years ago
I would reccomend a cheap ebay refractometer, doesnt take long to cool down a pipette or a few drops.
Post #8 made 14 years ago
Done and done. I hate using the hydrometer!I would reccomend a cheap ebay refractometer, doesnt take long to cool down a pipette or a few drops.
Last edited by Ralphus on 12 Jul 2011, 11:04, edited 5 times in total.
Post #9 made 14 years ago
I still use my hydrometer when fermenting as the couple of times I tried to use my refractometer it seemed a bit off the hydrometer readings (this was after correcting the reading for the alcohol).
Post #10 made 14 years ago
And licking the refractometer after taking a sample really isn't as satisfying as slurping down a hydrometer tubedeebo wrote:I still use my hydrometer when fermenting as the couple of times I tried to use my refractometer it seemed a bit off the hydrometer readings (this was after correcting the reading for the alcohol).
Last edited by stux on 12 Jul 2011, 12:30, edited 5 times in total.
Fermenting: -
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III
5/7/12
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III
5/7/12
Post #11 made 14 years ago
Deebo, i love my cheap chinese refractometer!deebo wrote:I still use my hydrometer when fermenting as the couple of times I tried to use my refractometer it seemed a bit off the hydrometer readings (this was after correcting the reading for the alcohol).
read this: http://seanterrill.com/2011/04/07/refra" onclick="window.open(this.href);return false; ... fg-results
it is a great improvement to the "traditional" refrac correction for alcohol formula.
Last edited by shibolet on 12 Jul 2011, 13:01, edited 5 times in total.
Cube:
fermenter: Sourdough Spelt Ale, Classic Lambic, Oud Brune, Barrel Aged Belgian Dubbel
Kegs: Bob's Black IPA, Blanc Blond, Soda...
to be brewed:
fermenter: Sourdough Spelt Ale, Classic Lambic, Oud Brune, Barrel Aged Belgian Dubbel
Kegs: Bob's Black IPA, Blanc Blond, Soda...
to be brewed:
Post #12 made 14 years ago
Thanks for that will give this a shot next time to see how close it looks.shibolet wrote: Deebo, i love my cheap chinese refractometer!
read this: http://seanterrill.com/2011/04/07/refra" onclick="window.open(this.href);return false; ... fg-results
it is a great improvement to the "traditional" refrac correction for alcohol formula.
Last edited by deebo on 12 Jul 2011, 13:58, edited 5 times in total.
