Wet water

Wet water is a staple of model railway scene building. It is water with a small amount (100:1 or less) of detergent added - washing up liquid, basically.

It can be misted or applied with a pipette to gravel, talus, ballast, scatter and other poured materials. The presence of detergent lowers the surface tension allowing the water to flow; this means that thinned down PVA can then be poured or dripped into place and will flow correctly.

Caveat: a domestic spray (as used for window cleaning products and the like) is too coarse and will scatter ballast everywhere. A misting garden spray or old perfume atomiser is much better.

You can also add a small amount of detergent to the dilute PVA.