Regarding Gene's comment in the previous post: does a final negative rinse in isopropyl alcohol negate the need for photoflo, or is photoflo added to the alcohol?

What effect does the alcohol have on the `archival properties of the negative?

Thanks, RIC

-- ricardo (ricardospanks1@yahoo.com), February 21, 2002

Answers

To 1 liter of distilled water add 2.5ml photo-flo (1/2 recommended strength) and 10ml 91% isopropyl alcohol. The photo-flo forms a sheet of water to prevent spots and the alcohol speeds drying.

-- Tim Brown (brownt@flash.net), February 21, 2002.

Wait, I didn't get that. Alcohol is surely evaporating faster than water, but since you have a large amount of water in your solution, how does the presence of alcohol in it change the rate of the water's evaporation ? I would guess that the alcohol would evaporate first and then it would leave the water on the film evaporate in its own (normal) time. There might be some other angle that I can't imagine, and I would be grateful to know about it. As for Photo-flo, it is effective in reducing the amount of water that stays on the film as you hang it, since it is altering its surface tension and therefore diminishes its ability to "stick" on a surface and form drops. If used in the right way, Photo-flo does a very good job.

-- George Papantoniou (papanton@hol.gr), February 21, 2002.

Sprint makes an End Run that is alcohol based. I think it does have a sheathing element in it also. I have used it on occasion with no ill effects on long term film.

-- Scott Walton (walton@ll.mit.edu), February 21, 2002.

Since Photo-Flo already contains glycols and alcohols, what is accomplished by adding another alcohol?

-- Ken Burns (kenburns@twave.net), February 22, 2002.

Water and alcohol form what is known as an azeotrope. When mixed, they boil together at a different boiling point to either of the two mixed liquids. A vast number of compounds form azeotropes with each other. The azeotrope of h2o & (ethyl) alcohol boils at 78.1 deg, which is lower than either h2o or alcohol, and the azeotrope mixture is about 5% water and 95% alcohol. If you mixed 50% h2o and 50% alcohol and boiled it, you would initially get a 5/95% h2o and alcohol mix come over together at 78deg untill the alcohol was depleted, and then get pure water at 100deg.

For this to help with drying, I would guess that adding a little alcohol to water would not help since the ratios are not on your side to promote fast drying, you would need to use a bath that was alcohol with a little water added. In fact, you might just try using pure alcohol (iso-propyl alcohol would work a little better as the ratios are 12/88% and 80.4deg).

-- George Paltoglou (stellar@optusnet.com.au), February 23, 2002.

I meant to say 25ml of alcohol, not 10ml. I got this from a post on USENET by Micheal Gudzinowicz. I can only say this formualtion works very well. The makeup of photo-flo is at http://www.kodak.com/cgi- bin/webCatalog.pl?cc=US&lc=en&product=KODAK+PHOTO-FLO+200+Solution

-- Tim Brown (brownt@flash.net), February 28, 2002.