High FG

[livo]

Ok. Thanks Mark. You are a wealth of useful knowledge. I honestly had not considered the burst of undissolved syrup in the tap. Yep. That would do it. I'd seen before, and knew about discarding the first tube that contains yeast deposit for later readings but hadn't considered the concentrate for the OG. My bad.

I know you are very strong on pitching rates, for good reason. It really is a shame that the kits don't take this into account. I can't see how an extra couple of grams would make a lot of difference to their bottom line. For my regular brews I usually try to use harvested yeast which gives a much higher pitch rate. A quick count of unused packets in my fridge yesterday was near 50 and I've used a few for other things.

What yeast would you recommend for an Old Beer kit?

I made the same mistake again yesterday, so now I know.

 

[livo]

I thought I should follow up by informing that the second brew also finished at 1.016. Identical, except I added slightly too much water. Oops. I think that the HBS guy's estimate of finishing at 1.010 was never going to happen. I didn't wait as long to bottle second time around. It hit 1.016 on day 6 and I bottled 2 days later. I have a third brew down as of yesterday but for this one I used a 1 kg dextrose / malt blend that does not contain the MD and I added an extra 200g of dextrose. SG is 1.052 measured without syrup from the tap.

After only 2 weeks in the bottle, the first batch is pretty good. It's up to my mate how long he can leave them. His second lot is already 5 days in glass. I think I'll need to make some of this for myself.

By the way Mark, the cans are only 1.7kg. I did some playing around with your numbers from above and it's all interesting stuff. Thank you for providing. I think the factor of 4 is missing from one half of your formulae though.

 

[MHB]

Where do you mean.
The two equations used are
SG to oP. SG=(4*oP)/1000+1
and
Mass in solution = V (inL)*SG*oP

Ok its been a long time (decades) since I did a kit, will take your advice on the mass being 1.7kg.
If there is anything else wrong with the calculations, show me and Ill redo the numbers.
Mark

 

[livo]

If I just use the numbers you have given above, this is how I see it. I'd be happy for you to correct me if I'm off the path here.

Using the tin at 1.8kg and providing 80% solids, as per your assumption, gives 1.44 kg solids plus 1.0 kg sugars, M.E. = 2.44 kg.
Total volume of liquid was 22.5 litres.
Your little table gives SG = 1.041644 and oP = 10.41089

The first equation SG = (4*oP)/1000 + 1 is the relationship between or conversion from Specific Gravity to degrees Plato.
= (4 * 10.41089)/1000 + 1
= 41.644 / 1000 + 1
= 0.041644 + 1
= 1.041644

This works but the factor of 4 inside the brackets is missing from the second equation.

M.E. = V * SG * oP
= 22.5 * 0.041644 * 10.41089
= 9.7548998211 kg

This answer is incorrect until I divide by the missing factor of 4 giving;

M.E. = 2.438724955275 kg, which rounded to 2 decimal places is the assumed mass in volume of 2.44kg.

So shouldn't the second equation be M.E. = (V * (SG -1) * oP) / 4. You could put the divide by 4 anywhere on this side, and to make it more related to the first equation it would be M.E. = V * (SG-1)/4 * oP

or we could write the equation as 4 M.E. = V * (SG - 1) * oP

Note: If you use SG as 1.041644 in the original equation you get and answer of 243.9999248211 kg, or 244 kg rounded which is order of magnitude out by 100 times. M.E. = 22.5 * 1.041644 * 10.41089
= 243.9999248211

 

[MHB]

No
The second equation gives the mass of solids-
The Volume times the SG gives the mass of the whole, so 22.5*1.041644=23.43699kg
Plato (oP) is % solids in W/W so as a percentage of the mass so times oP/100 in this case 10.41089/100 or 0.1041089
23.43699kg*0.1041089= 2.44kg (close enough) of the 23.44kg of wort is solids.

To cross check
2.44kg / 23.44kg = 0.104095 or as a % (oP) 10.41oP

It’s a good idea to keep all the decimals while doing the working but to round to something sensible (measurable) when you get the answer.
Worth remembering that the SG to oP equation is an approximation, the real answer is algebraic
Mark

 

[livo]

Ah. Thanks. That makes sense. Gotcha now Mark.


Edit:
So, why do I read my hydrometer (with no excess malt concentrate from the tap this time) on yesterday's brew with a Starting Gravity at 1.052 when by calculation this is clearly too high yet again? 23 litre volume (before pitching yeast).

By calculation from assuming there is exactly 1.7 kg in the concentrate wort can, and I added exactly 1.2 kg of other malt and dextrose. My target search using the equations says that I should only be in the vicinity of 1.0426 - 1.0427. That's nearly 10 gravity points out.

1.7kg X 80% = 1.36 kg + 1.2 kg = 2.56 kg
2.56 = 23 X 1. 04265 X oP
oP = 2.56/23/1.04265 = 0.10675140059088568217689457673695 or 10.675 oP

SG = (4 X 10.675)/1000 +1 = 1.0427

Possible explanations.
1) Not the full 23 litres, but I'm getting the right amount of finished product when I bottle.
2) Wort concentrate is higher net than the label says or contains more solids than 80%. Doubtful.
3) 1 kg mixed malt and dextrose bag weighs more than 1 kg. Again doubtful.
4) Faulty hydrometer but that would be 3 of them as I've tested them in sugar water solutions and water and they appear to be properly calibrated.

 

[MHB]

SG is non-unitary (it isn’t a "number") it can’t be manipulated in an equation like normal numbers.
The Mass Extract equation is a bit of a special case

Extract can be heavy, depending on how you mixed it could still be heavy at the bottom where the tap is. It requires very through mixing to get a good read.
If you aren’t sure, use a sterilised container and take a sample from both the top and the bottom.
Mark

 

[livo]

Yes. The exact thought just occurred to me when I was down in the shed. Layering or stratification (ie: uneven distribution of the solids in the liquid) could explain my high readings.

I usually do give it a fairly thorough stirring with one of those long handled plastic spoons. I put the can contents in, then fill and rinse the can 1.5 times with boiling water, stir all that to dissolve then add the sugars and stir again until there are no visible lumps. After this I continue to stir while I'm adding water from a hose in a manner that keeps the whirlpool effect going until it is halfway to the mark. I then usually give it a quick stir at the end, but I can't say with 100% certainty that I have completely even distribution. Probably don't with the hydrometer readings I'm taking.

 

[livo]

The first batch of this Old Beer turned out quite well as far as taste goes. My mate really likes the flavour, and I quite enjoyed it as well when we did the first sample at only 2 weeks in the bottle. It wasn't ice cold, but it was chilled. He has rung me today and given feedback on it fully chilled, which I asked for. He said that he finds it a bit flat. I went with the advice that it is better a little less gassy and only primed light. I'm considering the fact that as it was allowed to sit for several days (5 or 6) at the Final Gravity and there was no gas left in solution when I primed and bottled, this may have contributed to low carbonation.

I've bottled number 2 brew with light priming again, but it didn't sit for anywhere near as long at FG in the fermenter. I have number 3 in the FV now, so I'll probably bump the priming sugar up to my usual 5 - 6 g / 750 ml bottle.

I'll have to look at my notes, but I think I only used either 100g or possibly 120g of priming sugar in the 22.5 Litres. It actually ended up slightly more than that as I bulk prime by dissolving the sugar in about 1 - 2 cups of hot water and I bottled 35 at 650 ml so 22.750 Litres. I usually prime with 160g.