DIY Doctor UK DIY Forums

what should I use for pointing fireplace, I want a white finish.
fireplace is radnorshire stone which is quite flakey on the horizontal plane.
I am getting conflicting advice.
some say 1 white cement / 1 hydrated lime / 6 sea sand
others say 1 Hydraulic lime (not hydrated) / 2.5 sharp sand

is the first option problematic as I understand the mortar needs to be softer than the stone.

just use lime and sand, so hydrated lime with sharp sand 4:1 if the stone is soft the heat will expand the cement and make it crack,the lime and sand wont.

welsh brickie wrote:just use lime and sand, so hydrated lime with sharp sand 4:1 if the stone is soft the heat will expand the cement and make it crack,the lime and sand wont.

so 4 hydrated lime to 1 sharp sand (and no cement)? or the other way around?

I rang a specialist lime company earlier who said hydrated lime only lasts a few weeks before it looses its cement quality, so effectively, since it is on the shelf for a while, hydrated lime would be just like adding another quantity of sand.
he recommended hydraulic or fat lime. can you comment to this?

I have used hydrated lime and sand mix 4 sand 1 lime and havent had any problems,but if you worried add a small ammount of white cement to the mix.
I am not a lime expert but hydrated lime is easier to purchase in a bag,than lime putty,fat lime etc its available at most builders merchants

thanks, appreciate it.

is there anything I can coat the finished stone and pointing with to bring out the colour of the stone and will be safe and heat resistant?
does it have to be a breathable coating?

I was thinking wd40, is this a really stupid idea in a fireplace and above a fireplace?

you can paint a pva solution that will dry clear,or a silicone sealant like aquaproof try it on a small area first