Mortar colour samples test

danlightbulb

danlightbulb

danlightbulb

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Hi all,

In preparation for more repointing I've tested some combinations of sand. All the below are made from nhl3.5 lime in a 1:4 ratio with sand.

BS= building sand
PS= plastering sand
SS= sharp sand

Shown alongside two samples I got from Ty Mawr lime in Wales. Cumbrian and New London.

https://i.~ibb.co~/Jgm9B5d/PXL-20260601-083816057.jpg


You can probably see the issue. None of these colours would be any good for my house. The ones I have made have come out very light pinkish. They are all quite similar despite the different mix of sands used and the sharp sand is much more yellow looking than the other sands, but this hasn't made much difference to the final colour.

I want something much more buff brown and darker than these.

Any ideas?
 
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Agreed with @Armageus. Dyes or pigments so you can keep the strength of the mortar correct.

www.chalkdownlime.com

Natural Pigments

Natural Pigment - Red Ochre Natural pigment to be added to: Limewash, Lime Mortar, Lime Plaster or Silicate Primer and Paint. Naturally occurring fine powdered Kaolinite pigment - Made in France. Technical characteristics : Chemical name : Kaolinite - Goethite Apparent density : 508 g/l UV...
www.chalkdownlime.com www.chalkdownlime.com
 
The type of sand shouldn't be a problem. Both sharp and finer sands can be used for mortar it just gives a different finish. The house originally (1930s) would have used any old sand available locally or shipped in from somewhere. As long as the mix I use has a mix of fines and coarser aggregate it will be ok.

The problem is the colour.

The colour dyes are a reasonable idea but it sets up a much more lengthy and costly experimental stage as I will need to buy and test a bunch of colour mixes and be much more accurate with my measurements and records. I can't use cement dyes in lime mortar as they are incompatible so I need the more specialized, and not available locally, pigments.

I'm really hoping to solve it without the need for specialist dyes, because repointing the house will be a long term project not something that I will do in a few weeks in one go. I need something reliable long term in terms of repeatability.
 
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danlightbulb said:
The type of sand shouldn't be a problem. Both sharp and finer sands can be used for mortar it just gives a different finish. The house originally (1930s) would have used any old sand available locally or shipped in from somewhere. As long as the mix I use has a mix of fines and coarser aggregate it will be ok.
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Pointing is generally done with Builders Sand, so ideally you'd be best off just getting a small sample of builders sand from various different suppliers, as even "locally" they may source from different quarries etc. (and therefore be slightly different colours)

danlightbulb said:
I'm really hoping to solve it without the need for specialist dyes, because repointing the house will be a long term project not something that I will do in a few weeks in one go. I need something reliable long term in terms of repeatability.
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Unless you are stockpiling the sand, whatever you buy now might be different (in colour) than in coming months. Double that by using both builders and sharp sand, and you are adding even more variables.



Ty Mawr offer a full mortar analysis (£110), which might help if you believe it is just a case of mixing different sands
www.lime.org.uk

Mortar Analysis & Matching Service

Mortars can be seen in a wide range of colours and compositions across the country, they will vary from region to region as local sands, local sources of lime and pozzolans would traditionally have been used. It is the aggregate/sand that predominantly affects the colour and texture. It is...
www.lime.org.uk www.lime.org.uk
 
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Armageus said:
Pointing is generally done with Builders Sand
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Nowadays yes, not in the past though.

It's just about the aggregate on display rather than strength. With sharp you have larger material in the mix as well as finer material.


Armageus said:
Ty Mawr offer a full mortar analysis (£110),
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That is a very luxury expense unfortunately.

Im doing this DIY for a reason.



Ty Mawr have some great pre mixed aggregates, there's another place in Cardiff also. But nowhere stocks it locally so would be a big trip to pick up some bags of it in my car and obviously I can only buy a few at a time.

I don't need to match any other part of the building as in a heritage project. I just need to get the broad colour I'm looking for.
 
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Sharp creates a much stronger mortar than building sand, it actually looks quite nice but it is coarser rather than smooth.
 
200sols said:
Sharp creates a much stronger mortar than building sand, it actually looks quite nice but it is coarser rather than smooth.
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Yeah my understanding is it's needed for thicker mortar beds eg stonework. My house has quite thick joints, very uneven spacing too.

Some sharp won't hurt in the mix with lime, they work together is my understanding.

But as I've said, it's not the sand type that concerns me it's achieving the colour.

Ive done some cement repointing previously and it's very grey. Also the previous owner(s) did (or got someone in to do) the front of the house and it's a sloppy mess.

I want to achieve a mid buff/sandy brown.
 
Here is my neighbours house. Mortar colour is perfect - not too light that it stands out tye size of the joints, not grey. I would say it's a mid sandy brown with some red tone to it.

https://i.~ibb.co~/twRrPS9d/PXL-20260601-135657738.jpg


Here's the equivalent side of mine. Grey slop. I didn't do this, was done previously.

https://i.~ibb.co~/yBNtsX3S/PXL-20260601-135712771.jpg
 
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danlightbulb said:
But as I've said, it's not the sand type that concerns me it's achieving the colour.
Click to expand...
Achieving the colour is done by the sand though...

Builder's sand isn't the same colour everywhere. Even a few months apart buying from the same supplier I have had two different colours of builders sand (fortunately I still had enough of the first colour for the bit of pointing I was doing)

Shop about locally (ideally builders merchants where you may be able to get a cup sized sample for instance to try) - or if not possible, try differerent branded bags from the local DIY sheds (B&Q, Wickes, Travis Perkins etc) - they won't all be the same colour.
 
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Armageus said:
Achieving the colour is done by the sand though...

Builder's sand isn't the same colour everywhere. Even a few months apart buying from the same supplier I have had two different colours of builders sand (fortunately I still had enough of the first colour for the bit of pointing I was doing)

Shop about locally (ideally builders merchants where you may be able to get a cup sized sample for instance to try) - or if not possible, try differerent branded bags from the local DIY sheds (B&Q, Wickes, Travis Perkins etc) - they won't all be the same colour.
Click to expand...

Its sort of what Ive already been doing. The building sand I have came from B&Q and its definitely red. The sharp sand is mid yellow/brown, came from a different builders merchants, and the plastering sand is a red brown I would say and came from Tippers.

But they all produced a mortar colour almost exactly the same when mixed with the lime.
 
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Here's the colours of the raw sands I've got.

They are all quite brown. The sharp is top right, and most yellowy brown. I don't understand why the resultant mortar is not similar to these colours. Obviously the lime will whiten it, but Im getting very pale colours from these quite dark sands. I doubt I can get darker sands than these from anywhere.

Note the bottom left is kiln dried sand for comparison.

Just about to put them in the oven to see what colour they go when dry.


https://i.~ibb.co~/vvLCrNL7/PXL-20260601-163336772.jpg
 
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https://i.~ibb.co~/ZR6vW2gj/PXL-20260601-191425956.jpg

Post oven.

The sharp is a mid tone light brown. The building sand is a gingery orange, and the plastering sand is a browny red. Compare to the kiln dried sand which is a light yellow.

So don't really understand why these aren't passing through into the mortar colour.
 
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The lime will be lightening the mix a lot. Is there a reason you're going for lime? Its mainly only needed if the house has no cavity, or is made from natural stone.
 
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