Can one wash graphite out of felt?

You might want try a fabric eraser like this one. Any shop that sells quilting supplies or a fabric or craft store that has a reasonably good selection of sewing notions should have them.

Alas, there isn’t a fabric store for miles, and I was hoping to finish tonight :(

Do you have or can you pick up a gum eraser somewhere? They might have them at the drug store.

Also, you could try these things though I can’t vouch for any of them personally.

I hope you get the marks out. I’ve done similar things when I was first learning to quilt. Then I went to marking with quilter’s chalk. Well, who knew there was such a thing? :-) You might try something like a Chaco Liner, like this. next time. You can mark on either side of the fabric with something like that.

Good luck!

I have no hands on experience here, but it sounds tough to get graphite out of felt. It’s a perfect storm of possibly nano-sized particles stuck in the interstices of a dense fiber mesh. I’d consider a coating of something like white-out or paint if the graphite doesn’t easily wash out.

Is it possible to dye the whole project a dark color, making graphite invisible?

You should send a few test pieces through the washer to determine shrinkage or curling.

Wow! All of the suggestions are wonderful and helpful,even I learned something. I would of as always opted for the easiest way out. And for me would be to use a tool that literally cuts out the affected out and then wash the article because in the washing the felt shrinks and thereby, eliminating or diminshing the markings. Or just start over and use a not permanent marking tool on something that is going to be visible. I just try to not have to re-do too much, but it is in the redoing that we learn better techniques, right?

Anything worth doing is worth doing over ;)