Gradient mask problems for retouch

Hi, usually a quick solution to the kind of problem is flat all the layers, add some low noise and scale few pixels down.

If this is not working or u can't do that for some reasons, you have to use the healing brush tool or the clone in order to "heal" those areas. Another solution is to cut out the brushes (selecting them) and re-create their shadow from scratch. Doing this, you will avoid the blending problem you have.

Please let me know it this sounds reasonable to you,
Martin Benes

On closer inspection I noticed another issue – the general background and the background of the image of the brushes seem to be at different scaling (or were photographed with different camera positions).

That might prove difficult to address, especially if the montages combine multiple images of differently sized background structure.

Maybe this can help illustrate the point.

When the blending (by virtue if the Layer Mask) results in pixels determined by a mixture of both Layers’ pixels the result in the »soft« areas will be more noticeable the stronger the structure in the two Layers is,

Could you please post a screenshot taken at View > 100% and with the pertinent Panels (Layers, Channels, Options Bar, …) visible?

When both images display a noticeable structure the mixture resulting in a »flattening« is nothing unusual.

You could either use less soft Layer Masks or touch up the »seams« on a Layer atop them all.