Will cutting sand paper with scissors make the scissors sharper or duller? This is a little question that I have been wondering when I need to cut sand paper with scissors.
Sand paper can be used to sharpen knives etc. when applied parallel with the blade surface. Also it can be used to dull sharp edges when applied nonparallel with the blade surface.
My assumption is that it should dull the scissors since paper is being cut using the sharp edge and nonparallel with the abrasive material. But I still have doubts about the validity of the assumption.
How is it?
 A: Sand paper removes material.  When used properly, that removal of material can make a blade sharper.  However, when cutting the sandpaper, there is no attempt to structure the removal of the material.  It will simply dull the scissors.  It will remove material in a relatively haphazard manner, taking off the sharp edge.
If you have any questions of this, ask someone who sews for their nice fabric scissors, and let them know you're going to go cut some paper with them.  Find out how quickly they respond in an effort to avoid dulling their scissors.  Perhaps its not the most scientific approach, but it is a well documented one, and very evidence based! And that's just normal paper!

A: Duller
Scissors are sharpened by honing the narrow "chisel" edges, not the broad flat edges where the two blades sandwich together. Here's an image of someone sharpening tiny scissors with an even tinier file:

So, cutting sandpaper will abrade the point between the chisel edge and flat edge.
*You can use the sandpaper to re-sharpen the scissors afterwards, if it makes you feel better!
A: The answer given by Duller is halfway correct.When the blade is very blunt , the point of contact is flattened or shapeless. When you cut sandpaper , it being abrasive itself it abrades the blunt edge at the cutting point , this making the scissors sharper than before. The finer the sandpaper the better the sharpening. However this is not meant for light or sharp scissors. It is only meant for scissors which have started bending the cutting material.
