Brush settings to multiply color on overlap??

[media.tv]

Can anyone tell me how to adjust brush settings so that when a brush stroke overlaps itself it multiplies or intensifies (deepens) the color, as in this image? The stroke on the left is the normal setting so that the overlap color is the same intensity as the rest of the stroke. The stroke on the right shows the color is multiplied or intensified where it overlaps. 

I know it can work because I did it once but changed the settings and now I can't figure out how to do it again. 

I posted this question before but so far no one seems to be able to answer it.    Thanks!

[firstdefence]

As far as I can see, setting the brushes blend mode to multiply requires a separate stroke to activate the blend mode, using a continuous stroke will not activate the blend mode.

Below is an example, the first (left-hand stroke) is a single stroke, the right-hand stroke is three separate strokes.

[walt.farrell]

Setting "Wet Edges" on would give a similar effect for a raster brush.

[kirkt]

Also take a look at the difference in brush application of color between OPACITY and FLOW.  For a SINGLE CONTINUOUS STROKE, opacity will lay down partial color at the specified opacity and not any more color, even if you overlap that continuous stroke on itself.  On the other hand, Flow will lay down partial color in a continuous stroke that will build up ("intensify") if you overlap the continuous stroke on itself.

If you overlap multiple strokes (not a single, continuous stroke), then opacity appears to give a result a lot like flow.

Kirk