Pre-boil vs prepared wort

[cwrw]

Hi,
What should the difference in gravity be between pre-boil and boiled wort, as I did not observe this during my first two efforts? I thought this might allow me to stretch a bit more liquer from the mash (if there is a magic ballpark figure as a guide) :hmm: .

 

[Sean_Mc]

As far as I know there's no magic figure because of different variables such as brew length, boil time or liquid absorbed with different hop quantities....probably got that completely wrong
If you use a trusted recipe formulator and you've worked out your efficiency, just sparge to brew length or 1008sg which ever comes first

 

[Brewmarc]

As far as I know there's no magic figure because of different variables such as brew length, boil time or liquid absorbed with different hop quantities....probably got that completely wrong
If you use a trusted recipe formulator and you've worked out your efficiency, just sparge to brew length or 1008sg which ever comes first

Also different pre boil gravities will produce different evaporation rates.

 

[evanvine]

It's got to be directly related to the reduction due to the boil.
IE. 6 gals at 1040 boiled to 5 gals will produce a gravity of 1048 no matter how fast or slow the boil is.
Wort hung up in your hop bed just affects your BHE.
Hope I've got that right

 

[cwrw]

Thanks for the varied answers...interesting stuff! :thumb:
Evanvine - So that translates as a 15% loss due to evaporation; I think I'll be doing this instead of my usual 10% when entering the online calculation next time as I suspect that I've been coming slightly short upon my finished volume.Two birds with one stone!