I had this problem before. Removed the decor I determined to be the culprit and it has gotten better over time. But now I notice my snake has scratches again. And they are of a reddish color. Very similar to a cat scratch on your arm but on a smaller scale.
I have no idea how he does this. The only things I have in my cage now are coconut halfs and cork wood.
And nobody I know sands their cork wood so I am very frustrated I can't keep my snake scratch free.
How am I supposed to find out where the problem is?

I don't want to put him in a sterile tub for life since I am pro natural keeping and it seems other keepers don't have any problems with that.