Inkjet paper can be single sided or double-sided. In the case of single sided media, one side is coated for photo quality printing while the other is simply plain paper. With matte and cotton fine art papers, telling one side from the other can be a challenge. Here are some tips to find the coated printable side of your inkjet photo paper.
To start, inkjet paper is typically packed print side up in the box. If you have the box handy, compare your paper in-hand to some from the box. You might be able to match the sides with a quick examination.
If that does not work, take a close look at the paper under bright light. The coated side should look more uniform with an even pattern. The back will look more uneven and possibly rough. In some cases you will be able to make out the fibrous structure of the paper stock.
Coated side / front
Uncoated side / back
Another way to find the printable side is to lick your finger and lightly touch a corner on the front and back. Your finger will stick slightly to the coated side.
Finally, make a small mark on the front and back with a highlighter. The brighter more well defined mark is on the coated side.