Removing The Offending Section

Unfortunately you can't just fill the affected spot, or it would stick out like a sore thumb. Epoxy, as with pretty much any paint, will kind of fade and change color as time passes, although it's generally not noticeable unless you add new paint with which to compare. When repairing a ding on a car, this can be addressed using a clay bar or a scratch removal compound to mix the old and new paint together. Epoxy is made to resist that kind of tampering, though. So, to make sure the new blends with the old, you will need to remove a square of paint surrounding the area that is affected, to make the newly painted area big enough so as to not be obvious. A hobby knife or box cutter is very useful for this. Try to cut about two inches on every side of the scar, bigger if you are fixing an area that is very obvious, such as the middle of the garage floor. After the cut has been made, take a blow dryer and heat the area that is to be removed until the epoxy begins to soften, then use a paint scraper to remove the paint.