Sandstone Fence Blocks Want To Darken Sandstone Masonry Paint Can I Use Brown Fence Paint,both Water Based?

Want to darken sandstone masonry paint can I use brown fence paint,both water based? - sandstone fence blocks

I use the painting closely, even when both water-based, do not confuse good, and separate.
I want a tube of dark gouache painting artists buy and then add a little at a time until the desired color effect is, how to mix the colors and the mix of the party.