Detail bottles are 1/2 oz. squeezable plastic bottles with tiny applicator tips in different size openings. I like to create a mixture of 30% paint and 70% glazing medium. They are sold in a set of three, so I typically mix three different colors. From there the paint mixture can be applied to create string like effects. I find this works well for things like waterfalls, ripples etc.
In creating Looking Glass Falls (pictured) I used the the detail bottles to create the waterfall in a combination of white, silver and turquoise. There is also some impasto effect to give the waterfall more dimension. In contrast to the darker colors used to represent the rocks in the background this waterfall really stands out.