Confused

[SiHoltye]

I don't get how we achieve a mash pH, then sparge with water that's a higher pH than the mash and hope to achieve a 'Wort in Copper' figure that's beneath that of the mash? Sparge volumes for many are approx twice that of the mash liquor, no? Can anyone explain please?

Figures from Murphy's AMS pdf
Raw Liquor pH 6.0-8.0
Treated Liquor pH 6.0-8.0
Mash pH 5.2-5.5
1st Runnings pH 4.8-5.2
Last Runnings pH 5.4-5.6
Wort in Copper pH 5.1-5.4
Wort after boil pH 4.9-5.3
Beer after fermentation pH 3.7-4.2

[Goulders]

Because the grains will acidify the liquor assuming there is enough calcium to carry out the conversion and the alkalinity of the treated liquor is on the right ball park