Lime pointing colour

[tobydog]

Up until now the lime mortar / render I have mixed up has been used in places where it is later lime-washed. Final colour is therefore irrelevant. For upcoming repointing I want the classic off-white / dirty-white colour we often see being used by the pros. When I have mixed lime putty with sharp builders sand before I always end up with more of an off-yellow colour which won't match with the existing pointing. What are the magic ingredients to get that nice neutral colour?

Thanks

 

[noj]

Ty-Mawr's London mix is possibly the colour you want (may be too white) - but I don't know what aggregate they use - might be worth asking them?

https://www.lime.org.uk/products/lime/mortars/pre-mixed-fat-lime-mortar-london.html

 

[tobydog]

Thanks noj. That's pretty close. With the benefit of hindsight I wish I had bought a tub of buff pre-mixed. I know from previously working with the putty that I have that the mixture can be a bit wet to work with unless the sand is pretty dry. The putty from the top of the tub (after removing the water) is pretty sloppy. The supplier probably presumes the user will just use the whole tub in one go. It doesn't seem to work for bit jobs. The bricks I'm working with are quite rough so I'm going to need a semi-dry mix to keep it all clean.

 

[paulc]

I mixed some kiln dried sand 3:1 with lime putty - Ended up a fair colour match for OPC mortar. You could try to find a bag of white silica sand, although I don't know where to suggest unless you want one tonne dump bags.

If you only want a small amount of a coarse, but really white aggregate, I have a small bag (approx 2Kg) of marble that was left over from sifting a much bigger bag.

 

[Andys]

Slightly-too-wet pointing mortar does at least sort itself out in a couple of days on a board in the shed under damp hessian. My biggest problem is the supreme effort involved in planning that far ahead. Or in getting distracted and finding a lump of rock on the workbench a few weeks later...

 

[plasticpigeon]

In my experience the colour of the mortar is determined by the amount of fines in the sand. I have found that soft building sand adds quite a lot of colour, plastering sand adds little colour and comes out a very pale buff, and sharp (concreting sand from a builders yard) adds pretty much no colour at all. I use a mix of plastering sand and some building sand depending on the colour I want. I find concreting sand too gritty to build with, and plastering sand is sharp but finer than concreting sand so seems the obvious choice.