I don't know how andy uses his eraser, but I use mine to clean the contacts on my cell phone charger.

My bet is that the eraser is for cleaning the steel.

I have head of the use for cleaning contacts.

You use the eraser to clean the ceramic rod, I tend to use a green pan scourer pad and detergent on mine as well (it breaks down the oil in the marks). I guess that's why that is in the picture- but I think Andy said he uses his stones dry so the green pad is probably to move the steel filings off the stones.

I have got a big oil stone too, but it takes great skill to free hand sharpen so I Lansky my (good) blades so I don't wreck 'em.

Thank you kindly Paul!

oh yeah there Is a green scouring pad on the left as well!
my Crappy old CRT monitor at work leaves Much to be desired in colors! that green pad was like camouflaged!
But here at home w/ on my LCD.. can see it clear now!

man.. can't wait till all those old CRTs are phased Out!

Yikes, it sounds like your monitor at work is dinosaur old!!