[AgX]

One should distinguish between scratches

-) on the emulsion side
-) on the base side

(In case the base has a dulling layer refer to the first case. Antistatic surfaces on the base should be of no interest I assume.)

The refractory index of gelatin is said to be 1.51 (with listings going from 1.465 to 1.550)
A coating of some thickness (with the same ref.index as gelatin) on the emulsion side could reduce contrast but could also make image details visible again.

(Tri-) Acetate has a refractory index of 1.48

Polyester of 1.64


a) Coatings in order to fill the scratches:

Glycerine has a refractory index dependend on the amount of water absorbed covering the range given above.

Tetrachlorethylene: 1.50 (very volatile though)

A mixture of 9 parts Toluol an 1 part 1,1,2 Trichloro-1,2,2-Trifluoro-Ethane: 1.50

Oil of cloves*l: 1.55

Chinoline: 1.628

Monochlornaphtaline: 1.633

Monobromenaphtaline*: 1.656

*could be mixed too

(the tolerance between emulsion or base and the coating should be within 0.02 .


b) Coatings just to give a dulle surface in order to countereact the refractory effect,

c) dulling by another means,

d) Smoothening the gelatin, and thus the scratches, by repeated swelling and drying


I got all these ideas from a publication of our fellow member Gigabitfilm, who once made a factor-1000 enlargement of a pictorial negative and thus looked into film-surface problems.