Modification Marks showing up under resin when sanding?

This is pretty typical in my own experience. Resin is cast as a liquid material, and what you're seeing is an artifact or result of that process. If it doesn't go away as you smooth things down, I recommend heavy pigment blushing on the spot to disguise it away, like PanPastels blended to match the color. That's what I do for my dolls with visible seam marks after seam sanding.

 

Dumb thought while looking at that, it looks like a wicked cool scar xD if matching skin tone doesn't go well, I'd embrace it and add a few more 'scars' to make it look less like a seem. but that's just me

 

Yeah, i find PanPastels have so much rich pigment that they can almost totally hide that kind of thing.

 

The same thing happened with my Lusis! I think Rosslyn is right that it’s a side affect of the casting process and the best way to correct it would be blushing.