Lime or clay paint product for rough rubble stone wall

Rural_Puppy

Hello all
200 year old cottage. Coastal location west of Scotland. Thick stone walls rubble filled. Wall face area is 70m2 total. External Wall  faces have been  badly repaired previously with cement, painted over with (now blown) plastic paint.
Paint has been scraped off. Cement render removed, old mortar raked out. Repointing with lime mix mortar.
Wall looks uneven and messy so needs a coat of paint over the top. Must be fully breathable to allow moisture out. 
Question: what is best paint to use? Have seen products by Earthborn, Celtic renewables and various others.
Any advice for what would be most suitable? Thank you.

FreeBear

A bag rubbed lime finish would be in keeping with many rural areas - From memories of travels around the Scottish Islands & Highlands, a vernacular white finish sticks in my mind. I'd use some local sand mixed with lime and slap it on rather than spending a fortune on clay paints. If you wanted to add a bit of colour, mix some pigment in with the lime (Cornelissen is a good source of traditional pigments).

Rural_Puppy

Thank you Freebear. You are quite correct, the vernacular finish around here would be a lime wash over the stone. Which is the effect we are after, rather than the shiny masonry paint that was on there before.
Is the sand in the mix simply for texture, or does it help the lime wash to adhere? Or another reason?
You are right about the cost of proprietary lime or clay paints. Eye watering, particularly as some also require their own proprietary (also costly) undercoat first!
I have never made a lime wash before. Any tips on the best way to go about it? Do you know of any decent web sites that take you thru step by step? Thank you!

FreeBear

A bag rubbed finish uses a lime mortar - A typical mix would be three parts sand to one part lime. Using local sand saves on transport costs and would have been the material of choice in years past. https://cornishlime.co.uk/application-guides/technical-advice-note-for-bag-rub-finish/

If you wanted a lime wash, it is real easy to make your own - Simply take a tub of lime putty, mix well, Then in another (clean) bucket, mix 50:50 with water. The consistency should be similar to a thin single cream, so add more water if needed. Paint on in thin coats and allow to dry slowly, keeping rain off. If the coat looks too thin, that is good - Too thick and it will flake off when dry - You'll want to apply a couple of coats.

Rural_Puppy

That is really helpful. Thank you. Off to buy some lime putty, and a bag of hydrated lime. Self isolation is going to be an interesting learning experience!

FreeBear

Just stick with the lime putty - It will keep if stored somewhere frost free. I have tubs here that have been mixed & stored for three years (or more).

The more people that go in to self isolation, the fewer that will be on the streets - Great, it means I can go in to town without having to fight my way through the zombie hoards