Gravel

Yes, ink washes work very well for coloring sand or stone. Put everything in a covered jar and shake.

Another option is aquarium sand. It is available in many colors.  And, of course, there is always good old kitty litter.

I have used the lizard aquarium gravel purchased at Walmart.  Per Pete you can dye or stain it as desired.

BT

Sometimes it is easier to change the color of the ground cover after it is glued in place. Then there are no problems with drying the colored material and separating clumps later.

For example, I changed my mind about the earth tone I had used used for this big 25' long yard area. I originally used local dirt (it was free!), but later decided it was too light in color.

I just used a 2" brush to paint the whole area, ties and all, with slightly thinned flat black latex house paint to get the dark cinder color I preferred. Then, I added a touch of green for weeds and a touch of light gray ballast in a few places for variety.

You could do the same with any inexpensive ground cover material.

Jim

You might want to use chick starter grit. Tractor Supply sells it and it's pure crushed granite.

AGHRMatt posted:

You might want to use chick starter grit. Tractor Supply sells it and it's pure crushed granite.

I,ve been using it.... its great.... around a buck per lb, got mine in 5 lb bags....

a large bottle of ballast is about 8-10 bucks and covers the area in question.. under paint with matching color as a thick layer and apply to wet paint.  The alternative is to sift some from your your surroundings. 

I use white roofing granules (light gray) for ballast and it can work as gravel too. It's cheap! About $20 for 50 pounds. It is slightly magnetic due to an iron anti-mildew compound these manufactured granules are treated with, so be careful if you're running magna-traction engines nearby. (Experience is a tough teacher).