If you've moved over from black & white to colour in your darkroom or have just bitten the bullet and started colour printing from negatives you may be struggling to get prints with accurate colours. You may have already tried to fathom out how to adjust the colour to correct a colour cast and you'll soon realise how adding a bit too much of one colour will introduce a new and equally bad colour cast.
The learning process can be expensive and can result in a lot of wasted paper, and time!
The best thing to do to help you visualise how one colour effects another is to make a ringaround. This simple visual aid is a series of prints of the same photograph each made with a slight shift in colour.
To do this select a photograph that has a good range of tones and colours with average contrast. Spend some time making a few tests strips until you can produce a print that comes as close as possible to the original. This may seem like a waste too, but if you make a good ringaround it will help you become more proficient in knowing when there's a colour cast and what is necessary to remove it and the waste bin will start to see much less action.
Colour enlargers use Yellow, Magenta and Cyan filtration to balance colour. Two can be combined and adjusted to affect the primary colours Red, Green and Blue. To make things confusing if you have a magenta cast when printing from a colour negative you have to add magenta filtration!
To help you see the colour affect you now have to make a series of prints using the perfect picture you've just made. Introduce a colour cast in each print using each of the 10 and 20 values on your enlarger and print out the results. To make the Green, Red and Blue test photos use the filter values at either side on our chart. For example 20R needs 20Y +20M and 10G needs +10Y and +10C. When you have all 12 mount them so they surround the original as shown right. Add a sticky label with the necessary - filter value on each so they appear by each photo. This should then be put up in your darkroom as a reference poster.
The ringaround will indicate what you need add or remove when making future prints to ensure you get the correct colour. If, for example, you make a print that matches the colour in the 20R photo just look at the opposite end of the chart and add 20C to remove the cyan cast or take away 20M and 20Y. If it matches the 20M take away 10M or add 10C and 10Y.