The colored sides on an eraser are for different types of paper and pencils
Have you ever wondered why an eraser has a blue section or two different hues on each side? The blue side was somehow promoted for removing pen marks because a lot of people did not know what it was originally meant for. But the old theory about the blue part removing ink may be half true, after all.
In theory, they were designed to take your pen away from your paper, or at least that is what you all thought. However, you would be left with torn paper and unreadable notes instead. The soft pinkish-orange side is for lighter paper grades and light pencil marks, while the blue side is for the grainier, tougher paper since it needs a more sensitive friction eraser.