Colour in Earthen floors

Do we of anything (natural) to make the earthen floors black without effecting them any other way?

Hi Robert;  Yes,  checkout this site,   https://colorare.ca/

thomas rubino wrote:Hi Robert;  Yes,  checkout this site,   https://colorare.ca/

Thank you. Now that I know they exist I can try to find a uk supplier. So glad black is a option. Wanting black to retain the heat.

First thing that comes to mind is powdered charcoal. Not sure if it would achieve the desired tone your looking for but certainly an inexpensive and local source to look into.
If nothing else, it could be added to reduce the amount of a commercial colourant needed.

Let's hope so. Would be nice to see as well

I've never used coloring for an earthen floor, but I've used this company's pigments for adding color to lime plaster. They have a range of different products from more raw, unprocessed ochres to oxides with "higher tinting strength and opacity."

I haven't used either of these products personally, but here were two black colors they carry:
https://www.earthpigments.com/vine-black-pigment/
https://www.earthpigments.com/black-iron-oxide-pigment/

Also, I second Robert's sentiment and would love to see the final result!

Remember this website from another post using biochar in a wall plaster: Biochar plaster

Looks like it comes out fairly dark

I had been wondering about wood ash in a cob construction, to maybe give it a darker color. Wasn't sure though how it might react chemically. I guess maybe this is the bio-char that the previous poster mentioned. I wasn't aware that it was a thing before now. I have heard others mention adding different mineral dusts to earthen constructions as well, for color. Not to sure on the specific details though. I've also read about adding ox blood to cob. I think that had a different purpose than coloration, but it probly would give it a very dark brown color.

My builder used iron oxide and black tea to make a reddish earthen floor; it looked beautiful, like shiny terra cotta tiles the day I moved in. But it turns out it crumbled too much so now it's a bit more like a beach. And it turns all my socks red.