snip
This shows the sponge that runs across the full width of the printer at the 4 inch position. This printer has been used for some borderless prints, and the "end overspray" can be seen across the full length of the sponge. At the 4 inch position it can be seen that the opening over the sponge is enlarged to accept the "edge overspray" from the entire print head (about 15 mm), and the overspray from printing 4x6s can clearly be seen. At the far left edge of the previous photo, you can see the opening for the right edge of all paper sizes. These openings are why only certain paper sizes can be printed borderless even if you could hack the printer software - a full width slot must also be opened above the sponge in that position to avoid ink buildup that will transfer to the bottom of the following prints.