I developed few pice of color paper in RA4. The paper is 20 years old. White border is not so clean as it should be. I think I should use optical brightener - Tinopal SFP but it's hard to get. Can anyone recommend good replacement for Tinopal SPF?
You could use Phourwite REU or something similar. I may have garbled that name. Sorry.
If it is color age fog, it is possible that optical brightener will not help too much, but some effect should be in any case. Try to use antifog first. It the old paper base has been yellow, effect of brightener will be more evident.I have some old Kodak RA4 paper. The colours don't look too bad but the borders are a creamy-yellow and not white. Will immersion in an optical brightener cure that?
Since you seem to live in EU, I recommend you contact Fototechnik Suvatlar. They have a raw compound called "WA Weißaufheller" near the end of their price list, which is essentially what you want. It's not exactly cheap, but it works in tiny amounts and the powder compound lasts forever.
Just to clarify: I think you are saying that the effect is only there in UV light which for the most part will be daylight but once you view the print again in tungsten it will appear to be less bright. Presumably it it brightens/lightens towards the colour white those creamy/yellowish borders and then in tungsten light the creamy/yellowish colour appear again or does it?Remember, the paper and the process both contain brighteners.
The effect is only seen in the presence of UV radiation.
PE
Since PE already answered most of your question, here a quick summary of what optical brighteners actually do: they absorb UV photons and emit blue photons. As they age, they will turn yellow, which is likely what happened to Matt's now yellow paper stash. The emitted blue light makes the paper look brighter to our eyes, but obviously only in the presence of UV light.So WA Weissaufheller which appears to be a "white lightener" as a literal translation will turn or at least help turn the borders back to white? Does it only act on age-yellowing borders or does it also brighten the print as a whole. Is this the same stuff that doesn't work under tungsten lights as PE has commented? I presume that the chemical needs the UV component of daylight to work. If I am right in this presumption, once it has worked in UV, can I take it that the brightening effect is permanent i.e. it then doesn't lose its effect if the print is kept under tungsten light.
Since PE already answered most of your question, here a quick summary of what optical brighteners actually do: they absorb UV photons and emit blue photons. As they age, they will turn yellow, which is likely what happened to Matt's now yellow paper stash. The emitted blue light makes the paper look brighter to our eyes, but obviously only in the presence of UV light..
Benzotriazole, and to a much higher degree Phenyl-Mercaptotetrazole (see Michael R.'s thread in B&W section) create a bluish image tone by changing the course of development for image silver. Since all image silver is removed in color processes, I would not expect any effect from BTAZ and PMT.
Not so. The use of benzotriazole will restrain the silver fog development, and with it, the dye couplers that give rise to the yellowish base. I have used BZT many times with older color papers, and the results are often very impressive. Much less BZT is needed with color paper than with black and white. The only paper I have found thus far that it has not worked with for some reason is Kodak Portra, although in that case the paper was very fogged.
Perhaps so. I was reacting to the statement, "Since all image silver is removed in color processes, I would not expect any effect from BTAZ and PMT." Perhaps I misunderstood that. In my own experience benzotriazole has been invaluable in eliminating slight base fog (the kind that leads to a yellowish tint). I have not noticed any crossover, visually at least, and filtration has never been out of the realms of normality. I have never used PMT.I think that you have misunderstood the answer you are referring to. Antifoggants do change the fog in color prints and color film, but they don't change the tint on purpose. Often, they introduce color shifts by changing the way each layer develops. The most major example is with color paper becoming yellow by retarding the top (cyan) layer more than the others. Often PMT is the biggest offender because it is adsorbed most strongly in the top layer.
PE
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