Sand for final coat of lime plaster

[Bevmarley]

Hi can you tell what sort of sand you would use in your lime plaster for the final smooth coat. Looked up lots of websites but they just say sand.

 

[paulc]

For the little bits of plastering I've been doing, the final has been a mix of fine marble powder and lime. Not particularly cheap, but as it is going on less than ½mm thick, it goes a long way.

 

[Chris-Burgess]

Is this finish coat for the setting coat or external render ?

 

[88v8]

The sand must be sharp.
As described here
http://www.stastier.co.uk/nhl/guides/sandmort.htm

Unless you have a huge amount to do I'd be buying ready mixed lime plaster from a specialist. Failing that I'd buy the sand from a lime supplier, such as
St Astier, rather than risk a random result from a builders' merchants.

Ivor

 

[Flyfisher]

Or a chalk-based lime plaster instead of sand?
http://www.anglialime.com/products/wet-mix-plasters-angliamix-mortars-renders

 

[Easrow]

We recently did a bit of plastering around a fireplace. We found that you will struggle with sharp sand for the final coat. It's fine for the 1st one or two coats but it's too coarse for the smooth coat. We used something a lot finer like the sand used for block paving.

 

[a twig]

Normal (fat) lime or hydraulic (NHL)?

On the walls where I used hydraulic lime, NHL3.5 and plasterer's sand gave me a great finish for the final skim coat.

For normal lime I just bought pre-mixed - https://www.lime.org.uk/lime-top-coat-finish-plaster.html

 

[MikeG]

Or a chalk-based lime plaster instead of sand?
http://www.anglialime.com/products/wet-mix-plasters-angliamix-mortars-renders

Bingo!

All the plaster and render on my 300 year old old framed house was chalk based, with no sand at all. People talk about the flexibility of lime, its ability to cope with movement in a building, and then go and mix it with sand! That's pretty much the end of any movement. Chalk produces a much more authentic match to the historic plasters and renders, at least here in East Anglia, and it really will flex with the building.

 

[Zebra]

I went on a lime plastering course and they said to use block paving sand for the top coat.