Yes - another lime question!

[zunetunes]

Have read a number of threads all very informative.
Am needing to do a bit of repointing to a Victorian internal sandstone wall which will not be replastered.
1. I've ordered some lime putty, being delivered by courier as not available from the local builders merchant. Needed some other stuff delivered by Builders merchant. Told the builders merchant I wanted sharp sand for doing some repointing with lime. He said"oh you want plastering sand". Since I had only heard of building sand and sharp sand as major types I said fine. on getting home and investigating, it looks as though plastering sand is usually 2mm whereas sharp is 5mm. Am i best off getting them to change the order before delivery or is it likely to be ok?
2. I need to try to match the repointed bits with the existing. If the new stuff doesn't match too well, can I use some of the old crumbled lime mortar in my new mix to make it look more similar?
All the sand available round here is pink/red (like the pink/red sandstone prevalent here). My existing lime pointing is white/grey so I'm not sure what colour the mortar is going to be. How much does it take on the colour of the sand being used?

 

[chuckey]

The lime plaster finish coat is usually silver sand and lime, proportions? anything from 2:1 to 1:2 !! according to taste. This is why the top coat is so white. For the undercoat sharp sand is used (up to 6mm bits in it) round here its called concreting sand. Oh yes, soft sand is called brown sand even tho' its not brown? Its like being abroad!
Frank

 

[biffvernon]

But for repointing you really want sharp sand so I'd be tempted to change that order. The 5mm or more would be better and yes, chuck in some of the old rubbish as well.

 

[Ian Bond]

And when the mortar is 'green hard' (you can press a finger nail in, but not your thumb) brush up the pointing with a stiff brush to bring the aggregate to the surface.

That'll help to get the mortar a bit less white, and give it the right texture.

Be careful - if the mortar's too soft when you brush it, it will smear over the surface of the stones - not good.

 

[zunetunes]

top advice - thanks guys

 

[zunetunes]

Ended up buying readymixed plaster sand. All fine. However even when it is dry, its still more yellow than the original pointing which is much more white/pale grey. The sand around here is quite red - it's the only colour the local builders merchants do.
So what would the original builders have used that would have been so white, given that the local sand is red? There used to be both limestone and sandstone quarries within 5 miles of here.

 

[chuckey]

I do not use my local sharp sand, I use some from a quarry 40 + miles away. Find out the name of your local quarry from which the red sand is got, then look in yellow pages for for other quarries and visit/ask them about the colour of it. If you can find a lime supplier they might stock or know where to get other colour sand from. I have found "Rugby"brand sharp sand turns out very white, or you could use more lime in your mix.
Frank

 

[biffvernon]

I do not use my local sharp sand, I use some from a quarry 40 + miles away.

Bragging about the size of your carbon footprint? Or do you trundle your wheelbarrow the 40 miles?

 

[chuckey]

No, its actually relatively carbon free, cos its when XXXXs hyab comes to my local yard, it comes with my sand on it. Lucky for me the decent sand is available from a different branch of my local builder yard.
As a boast, my decorative sand (Weymouth white?) travels 305 miles in the back of my car, but then I would be doing the journey anyway, and I buy it by the poly bag not the dumpy bag!!!
Frank