TAC (Total Area Coverage)

When we use the term ‘saturation’, it’s often used as a way of describing colour areas which are too heavy. In fact, over-coloured areas can quite literally lead to saturated paper which in turn can cause problems with set off and accuracy of reproduction.

The ability of paper to accept heavy weights of ink is tightly calculated and managed. This is where the idea of TAC comes in. TAC refers to the Total Area Coverage of the 4 process colours on a printed sheet. For example, a bright red made up of 100% Y and 100% M would be 200% TAC. Fine. The colour ‘registration’ is 100% of all 4 colours so 400% TAC. Nightmare. Impossible to print at standard ink weights.

Our TAC is 280%. If your halftone images exceed this, our software may ‘open out’ the darker areas slightly using a subtle curve to limit the potential problems of over-saturation. In general, we will not alter ‘graphic’ content such as logos, text and boxes, so you will need to consider this if you are matching graphic content to pictures.

Acrobat Professional can check for TAC. Go to Advanced> Print Production> Output Preview. Set your TAC limit near the foot of the box and switch on so that your overweight areas are highlighted. You can even select your preferred warning colour.

It’s far better if you manage your content so that it’s below our limits when you upload. That way, we don’t have to tweak anything and your screen image is more realistic. In general though, you’ll find that the ‘opening out’ process involves UCR, or the conversion of C, Y and M to K only, so the colour hues should not change.