Black Limestone – Best jointing/mortar product? - Tile Advice

[Peter Knight]

Hello

I am looking for the best way to joint Limestone paving after having sealed it.

If I were to use a sand and cement mix, I am from various sources and info gleaned, thinking of:

• A dry mix of 2 dry building sand, 1 cement, plasticiser, SBR (quantity?) and possibly some cement colouring.

Does this sound OK or should I be using plasterers sand and a different ratio? Having the cement finish brushed and a little rough as opposed to striked appeals to me so could I use sharp/grit sand to make the surface a little rough? Or is that a bad idea?

I am looking for a solution that won’t crack or shrink and stand the test of time and so I have also been looking at the brush in compounds. I have laid the flags on a full bed of ‘strong’ mortar and there are several products that need the bed to be porous which excludes them from my thinking. The product that I think will do the job and not suffer from shrinkage / cracking is:

• Instarmac Flowpoint (rapid set flowable grout)

Does anyone have any experience or thoughts on this with regards to its application on sealed Black Limestone?

Thanks

Pete