Disappointing OG

[MikeG]

Oh-oh, I seem to have started a bit of a "domestic" here!

... but when people are asking basic questions about how to calculate the expected OG for a given amount of grain, I don't think "use software" is a particularly helpful answer, because it doesn't foster understanding.

Yes, mea culpa - I didn't understand. I've only done AG a few times and started with someone else's recipe, subsequently using trial&error for tweaking.

BUT Now I have Beer Engine all (well some) has become clear. ...AND I can fiddle about with different recipes to see quickly what the effects are.

...and now I've read Dunc's treatise I see what's going on but I think I'll save my brain cells and let the PC take the strain.

So, thanks to Dunc and thanks to Jim.
Mike.

[gregorach]

Hi Dunc

Thanks for the post with the formulae for calculating the OG of a brew.

No disrespect, you're a guru, but isn't this just what Beer Engine does?

Guy

Yes, it is - but I'm of the opinion that it's better to understand what your tools are doing rather than to just blindly accept whatever they tell you. Plus, I have actually had my computer crap out on me in the middle of brewday...

[MikeG]

All you need to know is the LDK (litre degrees per kilo) value for the grain(s) you're using and ...

Has anyone got a link to LDK tables otherwise I'm just going to have to rely on Beer Engine for my OG estimates!

Mike.

[jimp2003]

The values for Fawcetts malts is here: http://www.fawcett-maltsters.co.uk/specif.htm and simpsons is here: http://www.simpsonsmalt.co.uk/jps.asp

[MikeG]

Thanks for the links jimp.

So, I'm much happier now.

Today I mashed 4kg Maris Otter + 500g crystal. Acccording to Dunc's formulae this should've given me:

4 x 305 + 0.5 x 275 = 1357 degree litres.

I ended up with 22 litres so this should lead to 1357 / 22 = just under 62º but I only managed 50º so the efficiency was 50 / 62 = just over 80%.

Mike.

[norstar]

Hopefully I'm not hijacking a thread or digging up an old one unnecessarily, but it seems relevant so...

I've done a brew tonight and everything seemed spot on (including the mash efficiency when I reworked it after all was done at 77%). But Beer Engine indicated that I would get an OG of 1.050 based on a 14L brewlength but I only got 1.043 with 13.5L collected, basically due to evaporation rescuing me slightly as otherwise it would have been lower.

I've read about extract efficiency grain defaults and LDK in Beer engine and how pale malts are 300 ldk as a rough estimate. I've stored my grain in containers with clingfilm over the top and silica sachets in to keep it dry but they are nevertheless a few months old now. Would age reduce the ldk and contribute towards a lower than expected OG?

Or is it just that in Beer engine, the brewlength should be before taking into account losses to boiler dead space and hops rather than after, in which case adding the 3 litres I allowed for losses to the original expected 14 gets me back to an OG of 1.043. Coincidence?

[Rookie]

How you mill the grains can make a big difference in OG. My most recent brew was a stout with an expected gravity of 1.052. I ran the grains through my mill twice to get a finer crush and ended up with an OG of 1.061, a 17% improvement. I'm going to dig out the instructions that came with the mill to decrease the gap a bit and hopefully get the same results with only one run through the mill.