Hydraulic lime variability

Whats going on? I had two bags of Breckweg NHL2 and one bag was distinctly whiter than the other – and I thought they where all the same – well actually I didn’t! – they vary a lot.

In fact they’re all over the place and the NHL number is pretty vague. Actually the Breckweg technical sheet claims the pressure strength to be ≥ 2,5 N/mm squared, which is close, but so what? the tables for St Astier limes show a whole range of strengths associated with different mixes and they don’t look too hard – they even mention flexural strength and this is interesting because as a plasterer I am not really interested in compressive strengths, I’m interested in how it breaths, how flexes etc etc.

My advice with hydraulic lime is find a brand you like, stick with that one and see how it goes, I use two brands but never mix them together on the same project – and if your about to tut tut because I’m using the dreaded Hydraulic lime – I’m rendering onto a  cement rendered surface on a concrete block and metal lath background. Why? I’ll write about it later.

http://www.stastier.co.uk/nhl/testres/physmech.htm

http://www.heritage-lime.com/uploads/3/2/5/0/3250115/data_sheet_natural_hydraulic_lime-_nhl_2.pdf

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About byrnesurfaces

conserver and repairer of historic surfaces
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