Which mortar for soft Cheshire brick?

[carolelloyd]

Hi, I'm getting conflicting advice, from hot lime to nhl 2,3.5 or 5!

Help, which to use on soft Cheshire brick to replace damaged bricks? Hot lime most breathable, nhl 5 durable I believe?

Thanks

 

[stuart45]

The most breathable and softest is a pure air lime. I'm not familiar with Cheshire bricks, but the rule of thumb for mortar is that it should be weaker than the bricks. When repointing it should be slightly weaker than the original mortar.
How soft are Cheshire bricks? If you make the ,mortar too soft the worst that can happen is that it will weather away a bit quicker. If you make it too hard it can damage the bricks. However, for replacing just a few, it shouldn't make a lot of difference if you don't get it quite right.