It looks like it might be possible to glue delrin with 3M DP-8005 after this chromic acid etching process. I'll do some more testing later.
25g potassium dichromate
500g concentrated sulfuric acid
I guess this mixture is commonly called chromic acid.
Things that I should have done:
Use a Pyrex beaker
Don't use the magnetic stirrer, just use a teflon stir stick
Use an ice bath at the beginning of the procedure