Matching mortar

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hi,

I’m in the very early stages of planning an extension of or ref stock (they have marstons printed on them) 1953 built house. I have found a pretty good brick match but was wondering if any of you guys in the know could offer some advice on the mortar.

The existing house has a very light mortar with a course aggregate. It looks to be somewhere near the consistency of sharp sand but is perhaps a little finer. To match this up would a plastering sand/building sand mix with some lime in to lighten it a bit work? I’ve also been told Leighton Buzzard sand may be the way to go.
 
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You could try white cement as well as the OPC (ordinary Portland ) lime doesn't make the mortar particularly white. You'll need to experiment with different gauges in small ( exact ) quantities then when you're batching the mortar, keep to the same ratios, using gauges. Not just by the shovelful.
 
You need to find a sand that you can work with, as plastering sand makes bricklaying a lot more difficult.
 
There are many variables and even the drying and tooling of the joints can have an impact.

An extention is always going to appear new, even with matching bricks, and any attempt to mix consistant colour mortar on site is doomed. So its always best to not aim for (nor expect) a perfect match.

Red sand with whatever is going to give brown/medium grey. A yellow sand is going to a light grey/white/buff. Mixing different sands is hit and miss.

Leighton Buzzard sand appears to be a fine sharp sand, and your bricklayers would not want to be anywhere near that. They may deem the best place for it is down the cavity.
 
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Thanks chaps,
 
I’ve just added a couple of photos. I think a high proportion of the make up is fairly soft with a little bit of quite course sand but this on close inspection appears to be only white. Any idea? If I got the bricky to lay with a standard modern mix, would it be add much to the overall cost if it were then pointed up in a gauged mortar?
 
Re-pointing normally around £30 per metre but probably more in London. You could put a sample of mortar in acid which would leave you with a sample of the sand. Use the sand to build the extension and allow for it to weather in. You do pay a fair bit of cash for a mortar analysis and the mortar made up to match.
I've found that adding a bit of black helps matching older mortar, but I've only done it for small patches. New mortar seems to match in better if it's a bit darker than the original.
 
I’ve just added a couple of photos. I think a high proportion of the make up is fairly soft with a little bit of quite course sand but this on close inspection appears to be only white. Any idea?
I doubt if anyone added sharp sand to the mix. When the joints are first rubbed up with a metal tool it covers the joint with a thin film of cement. After a number of years the weather takes this off and exposes the aggregate which is what you now see. Even building sand contains a number of larger particles, but unlike sharp sand they tend to be rounded.
 

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