That didn't make much sense, but if it's what I think you're trying to say, the fragility of original silk screened decals will vary with every single example you'll come across.

Cases in point:I've had a near-mint '72 Schwinn Speedster with silkscreened downtube lettering that virtually polished off completely with the slightest single wipe over the top. However, I recently acquired a 1969 Schwinn Racer in nearly identical shape with the same downtube silkscreened decal - and have successfully rubbed the decal multiple times with very little loss of the decal's vibrancy.

There's no hard and fast rule to polishing silkscreened decals, other than to be careful. Try a small, inconspicuous spot and work from there as you see fit.

-Kurt