i'm not a senior member here (what does that mean anyways?), but i do know that nose oil or oil from behind the ear (better grade of body grease from what i was told) works very well to mask certain kind of scratches. the oil spreads the light and sometimes it masks scratches.
i made the unfortunate mistake of dropping on the darkroom floor a 5x7 negative of our state's governor (before he went to prison that is) and when i nervously picked it up to make the 150 5x7 glossies it had some scratches. i was nervous enough that i had plenty of behind-the-ear-oil and after i covered the whole negative it was inspected by the studio owner (who made sure i used ear oil not nose oil!) and into the solar enlarger it went. the prints were scratchless, and were published soon after ...
before i used some sort of bottled chemical to mask a scratch, i would attempt a little body-grease, it might just do the trick.