food colouring question?

i'm making some playdough for ds (my first time making it) and was wondering can i put food colouring in it? is this safe? will it stain his hands?

thanks

I used blue food colouring and it was fine! Good luck and have fun :)

thanks boomba! I used blue and green food colouring and the playdough turned out perfectly!

In case anyone wants to know, the recipe i used for my playdough is this (you can of course double it for bigger quantities, I made 2 lots, one green and one blue):

1 cup plain flour
1 cup water
2 tblsp cream of tartar
1 tblsp olive oil
food colouring

mix all ingredients in a pot over medium heat until it conjeals (i stired the whole time and i used a whisk in the beginning to get the lumps out).

once it was done I turned it out onto a board and kneaded it until it was smooth.