I'm just discovering my way around in the dark room. I've got some b/w negs and access to a colour enlarger and colour lab. I want to turn my white to blue, what filters do I use to make blue? I can get, brown, I can get red, orange.. But somehow I can make blue or green.

-- Neil Thrussell (softtouchphoto@hotmail.com), November 21, 2000

Answers

Neil, there is a simple rule of thumb for color reversal printing that may help you get things sorted out. It is, “ALWAYS DO THE WRONG THING!”. I think you’ll find this rule always works! (skip the next paragraph if you just want to know what filter to use).

The way to use the rule is like so: you want to make your prints go blue, so intuitively (to a novice) it seems like you ought to ADD a blue filter (to your filter pack). But, following the rule to “do the wrong thing”, you can see you actually need to REMOVE some blue filtration. There is, however, a slight problem; a conventional color head (subtractive) won’t have a blue filter. It will only have cyan, magenta and yellow. However, if you know that yellow and blue are complementary colors (like opposites), you should be able to see that colorwise, ADDING YELLOW is equivalent to REMOVING BLUE.

So the simple answer is, to make your print turn more blue, add yellow filtration to your filter pack.

PS; you ARE using color paper done in an RA-4 type process, aren’t you? This is the standard setup for printing color negatives and is necessary for the above system to work. Hope this helps. Just remember, “always do the wrong thing!”. BTW, the complementary (like opposite) color pairs are: cyan vs red, magenta vs green and yellow vs blue.

-- Bill C (bcarriel@cpicorp.com), November 22, 2000.

Also, with the B/W negative, you need a "negative mask". All this is, is a developed unexposed part of the film to sandwich with the B/W neg. If your printing 35mm, use the unexposed leader of the film, 4x5, just use a cleared sheet of film. You might start out with a setting of 100 Y and 70 M as a starting point. To get the colors for the paper, you need the mask (orange clear negative). I do this a good deal and you can really perfect a look... slight blue for a snow scene, slight warm for a portrait and so on. Cheers

-- Scott Walton (scotlynn@shore.net), November 22, 2000.