My old boss use to say don't erase in the field book as he was erasing.:-)
Why not just line through the unwanted lines? My 2 cents, Jp
On a photo mylar, all the line work was on the backside. Plain water and a dull letter opener or something similar would take off what needed to be changed and there was no damage to the matte side where you could ink on the changes.
This is what you want:
http://www.discoprint.com/default.asp?CatID=186&P=True
I bet they've gotten hard to find. Can't vouch for this particular vendor.
When the ink is old and has "cured" to where it's really hard and tough, resisting even these cores, I recommend you get a bottle of citrus cleaner (I used to get it at a bike shop) and put just a drop or two on the dry ink and then hit it with the solvent-loaded core in your electric eraser.
one word - Replot
if you drew in CAD then just replot it.
erasing ink off mylar makes the plan look sloppy. the white mylar coating is also erased & leaves a see through hole in the film.
A white vinyl eraser (retractable eraser pencil is good) and 409 will take off any ink that I have ever seen. The problem is that the liquid will wick under any eraser shield that you lay on top of the plat if you have too much on the eraser. I would spray a small bit off to the side and lightly dip the eraser in it and then erase. Do not spray over the map because any stray speck will take the ink off where it lands. Practice on something that you can throw away before trying to remove anything on the map you want to keep. I have sprayed an entire certification before and wiped it off with a folded paper towel and you couldn't even tell where it was. The problem with using 409 is that sometimes it works too well.