Using LR3's Adjustment Brush to "UnDo"

Instead of using the adjustment brush and a negative clarity setting to paint in a skin-softening effect on a subject's face leaving only the eyes and lips untouched, I'd prefer to apply negative clarity to the entire image and go back with the adjustment brush to paint in positive clarity and sharpening to just the eyes and lips.

My question is, will the eyes and lips be just as sharp that way? Or once that negative clarity step has been taken, subsequent actions can't bring them back to that same level of sharpness?

Hopefully, I'm asking this question in a way that makes sense. Thanks.

If I understand what you're asking - you're wondering if you essentially "blur" the image a bit with clarity (still in LR), if using an adjustment brush will bring it back?

I'm not sure, my guess would be that it depends on the order in which Lightroom processes things. If Lightroom processes the adjustment brushes after it processes the rest of the image (like I believe it does), then probably not. Then again, Lightroom has full access to the original image data, so possibly not.

My gut tells me that for leaving something untouched vs. applying an overall effect and then applying a countering effect, the former would give you a better result.

Have you tried this in Lightroom? It should be pretty simple.

The positive Clarity on the brush would cancel out the global negative Clarity. However there might be a problem with the sharpening applied with that brush. Brush sharpening is the same as whatever is set in the Detail panel, just more of it. Presumably, if you are doing negative global Clarity, you would be doing minimal or no global sharpening and that may leave the brush sharpening less than what you want for the eyes.