Quote Originally Posted by sanking
I sure did not know that. Assuming the information is correct, what would be the reason for using a blue base?

Let us know if the sodium sulfite soak removes the blue cast.


Quote Originally Posted by rjr
No. The three companies have very different approaches towards base, AHU and sensitising of their emulsions.

Efke uses a clear polyester base for the rollfilm and they use the same dies Kodak, Ilford and others use plus a blue AHU laquer (which comes off in presoak or developing). Sometimes a pink cast is left after fixing and washing and this will clear with a soda bath or some hours in the sun (I hang the cut film in the sheet on the inside of a window).

IIRC Forte uses a plain triacetate base with greyish tone. Havenīt used it in a while.

Foma uses a polyester base, too. But this one has a tint that will not fade or wash out.

Let me cite the spec sheet for Fomapan 100 (from www.foma.cz):


The following bases are used for manufacturing the particular sorts of the film:
120 rollfilm - a bluish polyester base 0,1 mm thick, furnished with a matted
backing which will decolourize during processing. The backing has anti-halation and anti-curling properties and prevents the incidence of Newton rings during

35 mm film - a gray or gray-blue cellulose triacetate base 0,135 mm thick,"

I donīt know which brand of polyester base they are using - many western companies use DuPontīs Melinex which is totally clear by itself.
I picked this up from another thread here on Apug.