For a true 50% black, the film must first be about 50%, not necessarily 50%, because the printing machine may print too small, or it may be blurred. This requires the printing machine chief to have a thorough understanding of the performance of the printing machine.

When it comes to the use of ink, you also need to pay attention to the characteristic that black ink is not black. Some ink manufacturers produce black ink with two blackness levels, namely general black ink and extra black. For products with a higher degree of precision, special black is a good reference choice, which can solve some of the difficulties in hue control.