Screen E-Book (.PDF) - MacDermid Autotype

And the winner is...Colour shifts58when you print a set of M dots on top ofa set of Y dots (or vice versa) is that thedot-on-dot effect fades in and out on aregular basis as some dots (say every 3rddot) are printed directly on top of a yellowdot (no dot gain) some are printed mostlyin the space between yellow dots (no dotgain) and some are printed on the shouldersof yellow dots and give gain. So thedot-on-dot gain rises and falls in a regularmanner, giving a more easily visible moiré.If the second colour is mostly above midtonethen the larger dots will, on averagespread out fairly regularly so the amplitudediminishes That’s why the lily print was soimportant. The M on Y showed up strongly,but Y on M had no moiré. However, onthe test strips the M on Y and Y on M showequal degrees of moiré (albeit with differentcolour shifts!) because the dot-on-doteffects are the same.This leads to a simple rule. If you know inadvance that the colour that is 15° awayfrom Y (some choose M, others choose C)will have significant areas of midtones ontop of relatively solid Y (and it seems thatY’s tend to be rather more solid than othercolours) then make sure you print the Yafter that colour. If you don’t have such issuesthen you can decide your Y print orderbased on the pure colour criteria of theprevious section.Seq Order Grey 3-Colour Shadow CFI1 CYMK 31 60 48 462 KCMY (Caza b) 40 63 60 543 YMCK 56 54 52 544 MCYK 33 65 56 515 MYCK 56 65 50 576 YCMK 48 56 46 507 CMYK 25 67 58 508 CMKY (Caza a) 27 62 54 48The overall winner is Seq 5, MYCK. This hasgood general performance with the bestcolour balance. It was often a favourite ofexperienced judges. Seq 3, YMCK, is alsoquite good but was always disliked becauseof its strong moiré in the lily. If theangles for the M and the C were reversedthen this would have been rated up therewith Seq 5 by expert judges.The Caza b, KCMY has a very strong greybalance shift so loses a lot of points forgeneral purpose printing. However, thereis a less pronounced 3-colour density shiftthan Seq 5, so gives quite satisfactory complexshades and the K-first strategy givesoptimal shadow performance which justifiesCaza’s endorsement of this sequence. Itwill also tend to be less prone to 15° moirébecause the Y is printed on top of a jumbleof other dots, making it less likely for themoiré to appear, another advantage.So, do we have an objective choice? Yesand no. We found the CFI incredibly helpfulin debating the various merits of the differentprints. By having numbers instead ofopinions we found that we could debatethe opinions much more sensibly. If wewere real printers then we would probablychoose to restrict ourselves to justtwo sequences, MYCK and KCMY. For anyparticular job we would be able to make aquick decision; if there’s a lot of subtle greythen MYCK would be used, if a lot of darkercomplex tones and shadows then we’duse Caza b.Do it yourself CFIHow applicable are our results to yourprinting? The sequence that was best forus will not necessarily be best for you. Thedot-on-dot gain effects will be different foreach stencil/mesh/ink/basing/lpi combinationso your results might differ.