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I am 30min's into a 4kg mash for my BOCK. I just got a call from a mate who said if the boil gravity is over about 1044 boil up your bittering hops separate as if it is higher than abot 1044 it will throw my hop calc's way out.
Well of coarse its going to be over 1044 i am aiming to hit 1067 at full vol, and i am only doing a 15 litre boil. So is this right or just carry on regardless? :(
There is a chart that shows the drop in utilisation with increasing SG but unfortunately I don't have it here. From memory, when I did a similiar thing the reduction was in the order of 20-25% with a 16 litre boil but that wasn't a high gravity beer. I guess you can add more hops or else you'll just have to wear the reduced IBUs. Maybe boil for a little longer - do you get much increase if you go over 60 minutes?
Good Luck
The Bock mash is fine - the boil gravity only impacts on the extraction efficiency of the hops - the heavier the gravity of the boil, the more hops you would need to add to compensate for reduced efficiency.

1044 is not a high boil gravity - its fine and you will be ok. Hop efficiency is pretty high up to about 1050 - that said, if you have calculated the IBU's on a full boil then you will have to add more hops to compensate for a smaller boil volume...I don't have the figures handy mate, but if your IBU's are based on a full boil of, say 23 Litres, then I would up the hops by about 20% to compensate for the small boil volume.

Experience will tell you how to go, after you've done a few part mashes..

Hope this helps,
Glenn Tinseth has done a lot of work on this. According to his findings for increasing gravity of the boil you will get a corresponding reduction in hops utilisation. For a 60min addition the utilisation figures are:
1.050 = 23.1%
1.060 = 21.1%
1.070 = 19.3%
1.080 = 17.6%
1.090 = 16.1%

The victorian era brewers often did boil the hops seperately in plain water: without lab assays of AA% etc I guess a hop tea allowed them to add as much of the tea as suited their palate. Modern thinking is against this, postulating wort-hop interactions absent in a plain water boil.

Utilisation drop is insignificant up to 1050, over about 1075 you need to seriously consider and allow for lower utilisation

Jovial Monk
If you are using a prgram like promash or beersmith then this will have ben taken into accoutn when you formulated the recipe (pretty sure at least, depends on what bittering method you are using)
Yep, you do get some variation with different gravities, according to Tinseth's data, but remember, those figures are probably based on a full wort boil.

[Edit: I went on about boil volume and then after a bit of a think, realised that the variation in boil size will directly affect the gravity - which is what Tinseth's figures are based on! :rolleyes: ]

That's why I "plucked" 20% - it works for me!

Thanks boys, i am 15mins into the boil and all is swell, i took a few pics to mark the historic moment. (my first part mash)
ps. the 4kg's of grain filled up the esky to the top.
Wait on, what the f*$#k am i doing talking to u guys, i got a boil going.
PSS. also there was no sign of "hot break" or as Palmer puts it "egg drop soup" after 20 mins, so i just added the Norther Brewer hops.
It doesn't matter if it's a full wort boil or a part wort boil, the hops utilisation for a 1.080 wort will be the same.

If doing a part wort boil, it's really simple to work out your additions. For example you're making 20ltrs of a 1.050 beer with 25IBUs, using 1 addition at 60 mins and the hops are 4% AA.

If it was a full wort boil you would use the utilisation figure for 1.050 which is 23.1%, so you would need 54gms of hops. But you are only going to boil 15ltrs and then dilute it to 20ltrs. To do this you will need 15ltrs of a 1.067 wort. So what you do is work out how much hops you need for 25IBUs in 20ltrs but use the utilisation for 1.067, or simply 1.070, which is 19.3%, and therefore you will need 49gms of hops.

You will end up with exactly the same amount of isomerised alpha acids by boiling 54 gms of 4% AA in 20ltrs of 1.050 wort for 60mins, as you do for boiling 49gms in 15ltrs of 1.067!

Again this is a simplified account, becuase as the wort boils and concentrates the utilisation is not a linear decline, but the basic principles are correct.

I know there are many programs that can do these calculations for you, but by learning the maths behind the programs, it will give a better understand what is happening and you are more capable of making adjustments on the fly.

OK boys its done, but what the &*@# is the go with Hallertauer plugs.
The mash went great,
the lautering was tops,
the boil was a breeze,
cooling was a cake walk,
but then getting the wort from the boil pot to the fermenter, i think i balled it up. All those darn hop flowers, so i started to seive them out but that took ages, then the phone range and i dropped the seive with a handfull of hops into the fermenter. Is that bad?
anyway i got a gravity reading of 1066.
Also i rehydrated the s-23 but after 40mins, nothing just separated in the jug. so i put some wort in and it just went cloudy so i just dumped it it the fermenter.
I started off fealing great but 5 hours later i am stuffed.
there was a bit of hop material in the OG sample, does that matter?
Anyway it was hard work.
MAH said:
You will end up with exactly the same amount of isomerised alpha acids by boiling 54 gms of 4% AA in 20ltrs of 1.050 wort for 60mins, as you do for boiling 49gms in 15ltrs of 1.067!
Agreed! ;)
I didn't have my notes handy, but I found my recipe spreadsheet and checked the formula (spreadsheets mean I don't have to remember stuff like this!)...

The formula I use to calculate hop additions is:
(Desired IBU x Volume of Boil in Litres x 10) / (A/A% of hops x Utilisation of Hops) - the 10 is a constant for metric units...
(25 IBU x 20L x 10) / (4 x 23%) = 54g of Hops! :)
and if we reduce the volume and raise the gravity, we get:
(25 x 15 x 10) / (4 x 19) = 49g of Hops!! :D
The important part is to know what the gravity of the boil volume is so you can determine the appropriate utilisation rate from Tinseth's table...

Easy, ain't it :p
Just about to sparge, i know i let the level get a bit low & risked the grain compacting down but it went great.

SJW said:
OK boys its done,
Anyway it was hard work.
Congrats mate! :D
I bet every brewer has their own story associated with each and every brew they've done - dropped this and forgotten that...That's how we get an individual brew, otherwise we'd all be making alcoholic cordial :p

The yeast, if it is cloudy, should be ok - it usually goes cloudy when its multiplying so you should have a short lag whilst the yeast goes through its adaptive phase in primary...

Given that you have chilled the wort before transferring from the kettle to the fermenter, you shouldn't have any dramas as long as everything was clean before you used it. The handful of hops you dropped - if they were the old flowers/plugs that went through the boil, they won't make a difference - if they are new flowers/plugs and you left them in the primary then you just did some dry hopping!

Either way, they shouldn't affect your beer - if anything they will add to the aroma of the beer.

I can _almost_ smell it from here! Well done... ;)
Now you can relax, sit back and have a homebrew (after you've cleaned up)!!
lautering into the boil pot after recirculating the first 2 litres for clarity

Oh no you have an air bubble in your siphon :eek: , and obviously your beer will be ruined by the evil HSA :( ! As soon as you have fermented and bottled this beer you should send it to me so you don't have to suffer the embarassment of serving HSA beer to your friends. My friends are beer heathens so they will know no difference ;) .

Nice piccie of the mash syphon. How do you control the flow out of the tun with that hose?!! [Edit: I just saw the next photo with the tap! D'oh]
Wort looks good for a pre-boiled bock...
The boil after the first hop addition

I got a tap on the end, so i did it real slow, just like you boss.
see the 2nd pic
And last of all the MASTER BREWER, or should that be the MASTER BATER :D :D