Why are some pencil erasers cruddy?

Ok, a pencil point, is a pencil point, is a pencil point. Thats obivous. No one complains about the quality of a pencil point. If they do, they simply sharpen it.

Why can’t pencil erasers follow suit?

How on earth do these erasers get out the door? I mean An eraser is supposed to erase, not mark up more! (American Classic - Papermate)

Before and after you use the eraser, do you clean it? I find that rubbing the pencil eraser against a sheet of clean scrap paper removes the built-up graphite residue and regenerates its erasing powers. You’re done once the eraser stops marking up the scrap paper.

if you erase long enough it will renew itself. Or you can perform this on a seperate piece of paper or cardboard, and it will work.

For the record, I’ve had erasers on fairly cheap pencils (and there’s the rub, I’m sure) that, no matter how clean or renewed they are, they seem more interesting in smudging that erasing. Why? Well, scientifically, physically, I have no answers. Fiscally, it’s cause they cost about 20 cents a piece.

I have to agree that pencil erasers seem inconsistent. Sometimes, they work just fine. But sometimes I’ll get some thing that’s like vulcanized rubber, other times I get some crumbly thing that’s like feta cheese… and I have found repeatedly that no amount of “cleaning” or “priming” will fix the latter two.

I disagree with your initial premise. Sometimes the points aren’t very good either. I have bought pencils that just couldn’t be sharpened without breaking.

I suspect your answer is cheap pencils => cheap materials.

Erasers do age and get worse over time. A pencil that has been around awhile can end up with a near useless eraser (or worse than useless by causing smudging).

The type of paper that is being written on can also have an impact on how well an eraser will work.

Erasers can be made of either rubber or vinyl. Rubber erasers tend to degrade after a while (oxidation?) and may also be heir to problems directly attributable to the quality of the rubber. Vinyl erasers (the white kind) tend to stay softer, clean easier, and erase better. I’ve found that they wear out a little faster and make more “crumbs”.

As for pencil leads, it’s all graphite with some clay mixed in for hardness. 100% graphite will give you a very dark, very soft lead that will lose its point very quickly. The more clay you mix in, the harder the point, but clay being cheaper than graphite, some manufacturers will cheap out and produce a point that’s more clay than graphite, which is brittle and won’t stand up to regular use or sharpening.