thats an easy technique to achieve. but a bugger to explain. so i'll give it a go, as no one else has yet.
try puting clean water on the area of dry paper to be painted, then drop a fairly heavy tint into that water, it should run out to the wet edge. if youve to much colour, remove the surplus with a dry brush and fade out to the paler edges. alternative would be to paint the strong edge first, and with a wet brush and befor it thinks of drying drag a tint to the other areas. its a sort of hit and miss effect that can be achieved in different ways by different people. i hope that helps
try puting clean water on the area of dry paper to be painted, then drop a fairly heavy tint into that water, it should run out to the wet edge. if youve to much colour, remove the surplus with a dry brush and fade out to the paler edges. alternative would be to paint the strong edge first, and with a wet brush and befor it thinks of drying drag a tint to the other areas. its a sort of hit and miss effect that can be achieved in different ways by different people. i hope that helps