I just got klaf for a new 11 line megilla and on the yeriah I was working on today, I came across this stuff which I'm not sure what it is. Im thinking it is Duchsustus, but since this is my first time with this sort of thing I'm unsure. It peels off with a knife just like the MB says, but it is VEINY, or it is shaped like veins. It is also whiter slightly than the rest of the klaf. I also have this yellow strip on the bottom corner of the klaf which peels off by hand and I think it might be Ducsustus but it is different than the "veiny" stuff.
Another question is what happens in the case a letter or part of one is written on this on a megilla, is in different than Tefillin since Megilla doesn;t have to be written on klaf?
If someone could please help me out with their opinion I would appreciate it!