Dot gain, one of the fundamental metrics of printing, has recently come to be called TVI or Tonal Value Increase. It’s a distinction without a difference, an attempt to deal with the fact that digital prints may not have dots, but specs. Maybe we could call it spec gain. Both terms describe the tendency for tonal gradations to “gain weight” as a part of the reproduction process.
Old-school thinking was “Low dotgain good, high dotgain bad”. Since CTP, thinking has switched. The feeling is that as long as we can control dotgain with curves, everything should be fine. but there is a fallacy here. As dot gain or TVI increases, press stability decreases. The curves that control excessive dot gain amplify normal press variations. The result is a shaky, unreliable press that can’t be controlled. The moral: uses curves for minor correction when needed, but beware of overly-strong corrections. In the long run, they will fail you.