While inspecting a model for stray reverse faces (which don’t have a problem in Sketchup, but cause flickering in Twinmotion), I made the back material bright red in order to see it better - and realized that I have a lot of… not sure how to describe it - reverse edges? Some parts of the model have a lot of bright red thin lines that flicker in and out of sight.
I see that both Material Tools and Cleanup3 have an option to “remove edge materials”, but I’m wondering if there are any downsides to this? Like, what effect does it have long-term on a complicated model? Any changes to the behavior of applied materials? Any issues with UV mapping?
I just want to know for my own enlightenment, as well as to avoid a situation where I apply a global change to the entire model, then make a bunch of other changes, and then realize - 500+ changes later - that something is foundationally messed up and I should not have done that.
Soo… to Remove All Edge Materials or not to Remove All Edge Materials?
To clarify: the red edges are NOT from “color material by axis”, I have that set to “All Same” (black). These are railings generated by a dynamic component, so god only knows what their geometry formula is like.
look at your style. your backfaces are red. (edit : ok, reread your message, you know it’s red 
)
this is the backfaces you’re seeing, bleeding through. it might be enhanced by hidden edges (normal edges will be on top of that bleed)
you can dismiss them so long as you’re exporting images with a more neutral style.
oh yeah, about your question, I’m not sure what’s the point of having materials on the edges except if you’re using a style where lines are material-coded.
it would probably shave a sliver of weight in your file.
@ateliernab has already said those are back face colors leaking through, not edge colors unless you have explicitly set edge coloring. Especially if the model is far from the origin, this is an occasional glitch in the graphics view, that again as he noted, is usually concealed by the default black edges. I don’t know of a fix.
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Out of interest why not save a copy of the file then delete the edge materials on the saved copy to see if that fixes the issue or whether the back face still shows through.
My previous experiments with bright back face colours always failed because I could see traces of the colour.
I would be interested to hear how you get on 
Did that, don’t see any issues so far, everything looks the same.
But my worry wasn’t doing a global operation whose results I can see immediately.
It’s doing something and then discovering NNN hours later that I shouldn’t have. That’s why I’m being paranoid and asking if there’s any consequences.
