As far as I know organic dyes don't work in concrete.

Interesting read here Rick.

Here is a link that might be useful: Natural dyes

David-weren't you talking about trying compost as a dyeing agent?And,peat will stain white cement.I'll keep trying with what my wife is doing,see how it goes!
Cheers from here.

Yep the crete comes out of the compost with some pretty vibrant hues. But it fades pretty fast.
I'm wondering if I can seal in the colors before they fade.

How did you make out with the purple nurple medication?:)
If I could find a purple and an orange pigment it would make my day.

I have coal black that glistens in the sun.
Just black pigment grey Portland and 4 parts copper slag.
It glitters like black metalic paint. Very cool.
I picked up some clear sand blasting glass now using white pigment, white Portland, and 4 parts sand blasting glass you have 'blinding' metalic glittering white.
White Portlands isn't white enough and white pigment is cheap.

I'm going to make some black and white objects. Maybe a 1920s style birdbath in glittering black on white.

If you want whiter,try adding a measure of POP.A recipe that came with our masks recommended it.
cheers from here

A POP recipe is on my list.

Both Gardencast and Hydrostone are made with POP and they are pretty expensive but highly rated.

Have you tried either of them Rick. They are designed for what you do...casting in crete.

I figure to try to make my own for a third of the price.:)

Keep in mind that to dye fiber or yarn with most natural dyes, one must add a mordant, anything from acetic acid or alum. How would that change the concrete "stuff"? even at that, most natural dyes are quite delicate and prone to fading. Maybe you could use acid dyes (like Rit brand) but even they take the addition of salt or vinegar to make them at all permanent.
spiderwoman

Well,I'm gonna try with some leftovers from my wife's most recent dye job(she uses alum).I'll use the "water"in the mix,not as a finish.
Hey,nothing ventured,blah,blah,blah...
cheers from here

Hi spiderwoman
Do you like spiders BTW. I love the critters. My favorites around the house.

But my question is about dyes.
Are acids an alum used to set the color?
I'm wondering if there is a way to set color already applied.
White portland Hypertufa cured under a compost piles can come out with a very rich patina of colors but they fade pretty fast.
I'm wondering if there is anything I can apply to the pot fresh out of the compost that might help set the colors.
Not so much against UV but even for indoor use.
I've had a beauty come out of the compose with orange black and green only to have them fade to a muddy light brown.