my epson wf-2860 won't print without borders on photos, what am i doing wrong?

You must select a compatible borderless paper type and size. The setting is in your Mac's print dialog.

1. In the print window, select the Paper Size setting matching the loaded paper.
2. For borderless photos, select the Borderless checkbox or a paper size with a Borderless option.
3. If creating a custom paper size, the Quality setting is limited to Normal.

IF THAT DIDN'T WORK: Verify your paper is on the official borderless compatibility list.