Hello! I have had this issue on Corel Painter 2019 where some brush marks turn darker and the edges harden all around. I've tried different settings but haven't found a solution. I think it might be something simple I'm overlooking? Here below is an image with brush strokes made by Detail Opaque, but it happens with lots of different brushes and sometimes they work normally, sometimes they turn out weird like this. The pencils behave like this sometimes too.
I have a Macbook Pro from mid 2012 and am currently running on Catalina, but I had the issue before too.Any help would be greatly appreciated, thanks.
I think what you are running into here is the layer automatically converting to "Gel mode", For example with these steps:
1. in Painter 2019, create an empty layer (it's very imporant the layer has not been painted on yet!)
2. In the brush selector, choose the "Chalk Pastel and Crayons" category and paint with "Basic Crayons". Note that the mark has the dark core and light fringe. Also note the layer composite method has automatically switched to "Gel" (this can be found in the layers panel)
3. Paint with Detail Opaque. It also has the "gel" look.
4. In the layers panel, change the layer composite method to "default". The gel look is removed.
5. Now create another new empty layer (once again it's very imporant the layer has not been painted on yet!)
6. Paint with Detail Opaque. Note that it remains opaque, and the layer composite method remains at default.
Now in your screenshot, the selected layer is not gel, so I'm not 100% sure this is the issue but hopefully it's a start...the bottom line is this: check the layer composite method as it could be the issue.
If this is, in fact the issue then we can talk about the next step in how to avoid this behavior entirely...