Quote Originally Posted by Blighty
Some years ago, I thought I'd try my hand at colour printing. As it happens, I never got round to doing so. But something has always puzzled me. When it comes to printing, why must the filtration be adjusted for each individual negative. Surely, the filtration would be the same for different subjects taken in broadly the same type of light. Obviously one would have to filter out major colour casts from let's say a tungsten light source. But otherwise, once a suitable filtration had been found for the neg/paper/light source/chemistry combination, would this not apply to the remaining negs on the film.
Regards (at the risk of sounding really thick), BLIGHTY.
You don't sound thick, at all, to me.

There are a number of factors affecting color balance: the color temperature of the lighting is one, and probably the most significant. There will be variations due to processing - the age of the chemicals, the composition of the water used to mix them,... I couldn't begin to list them all ... I think the phase of the moon, whether Saturn was in Aquarius ... might have something to do with it all.

Frame-to-frame variations are less severe, however, even the positioning of the model in a mixed lighting situation can result in a different color balance, for example.

Normally, in the first frame I take, I'll have the model hold a gray card; from that I'll get a usable reference for analysis. From there, It all depends on the eye and taste, and perfectionism of the photographer - in this regard, it is no different than working in black and white.