Dying grout

Hi,

My question is can I use a wee drop of black food dye to colour pre mixed white grout to grey?

I'm tiling a hearth of a fireplace, (which will not be operational) and the grout obviously won't be exposed to water,

As it's a very small area to grout I wasn't wanting to buy a large bag of expensive grout and the only small premixed tubs that I could buy locally were white,

My question is will this in any way cause problems to the grout when curing or will this work, I reckon it'd be a very small amount of colouring needed to create the desired shade

Any advice greatly appreciated

Cheers

Why not mix a bit up in a saucer or plastic food tray and leave it a couple of days to see.

Yeh good shout I'll give that a try

Better to use powder paints, food colours are nearly pure alcohol and may not mix well.