I only used their "Realistic Water" for larger areas, as it does
tend to shrink a little. Their "Water Effects" doesn't shrink as much,
if at all, and may be the better option. There is also "EZ Water" but
this has a tendency to form a mercury-style meniscus due to its thicker
consistancy, and getting bubbles out of it quickly is rather difficult.
I tend to stick with plain old Acrylic Medium / Varnish nowadays, as it
CAN be layered. I use Liquitex Mediums which are just brilliant. Their
Gel Texture Medium is superb for water effects such as ripples, rapids
and the like. Highly recommended products !!! Available at top quality
artist supply shops AND (of course) on-line. It is a less expensive
method to boot !!!