When I took off my rudder blades to refinish them (they are EPO 1s that had been left in the sun) I noticed that the head of the starboard blade was split. I thought I might inject epoxy+hardener+aerosil into the crack then clamp the two sides together. But I'm unsure how I might prep the internal surfaces? The crack is probably around half a millimeter wide at most so not very accommodating to prep work. By all I've read prepping seems an essential step of the process. Any suggestions?
Photos:
https://imgur.com/a/0cI9mKQ