Anytime Railroad modelers do any kind of scenery these days, "wet" water is a mainstay item. The surface tension of water has to be defeated to get the water to flow onto and into the scenery materials being secured, in advance of adding the thinned matt medium or white glue.
The usual approach is to add some liquid detergent into the water, or to use "Photoflow" from Kodak. And this approach usually works very well.
But currently I'm using some groundcover products that are proving to be difficult to get the "wet" water to soak into. In particular is the "Light Cinders" from Scenic Express. There's a lot of very fine particles in the "Light Cinders " ballast and that seems to be causing the problem.
But I've found a solution.
And man it works gangbusters!
I'm finding that I'm spraying far less water than I used to get the texture materials ready to accept adhesive.
Give it a try!