Offset Printing: what is too far off?

[Lordrhavin]

We all know that it is technically impossible to have a tolerance of absolute zero between colours in offset-printing. But, lets guess you have white text printed in plane one and a blue text printed on top of it, slighly smaller. Are there any norms, standards etc. in the EU or other countries defining exactly what is to much off? If two dots at exactly the same position in a pdf in different spot colors appear 0.5mm from each other in the print, is that too much off?

For me, it clearly is, i'd expect a tolerance of ~0.1mm, but: is there a norm or anything else on that?

[Ton Frederiks]

I am not sure if the Illustrator forum is the right forum for your question, but I Googled this discussion:

https://printplanet.com/threads/offset-trap-size-industry-standard.3631/

[Lordrhavin]

i didnt find a general forum for that.

[Ton Frederiks]

That's why I gave  you the link to that discussion.

[Mike_Gondek]

.5mm is very reasonable, and that falls well with trap amount for offset/lithography @133lpi. 

The classic rule to calculate trap amount is equal to half the diameter of a halftone dot. eg:  Divide 133lpi into 1 inch to get .0075" diameter of the dot. Divide that by 2 to get the suggested trap rounded to .004".  Your .1mm max tolerance expectation falls just under .004"

[Lordrhavin]

Are you serious? A text with line-height 2mm and an offset of 0.5mm between color separation planes would be completely unreadable.

[Doug A Roberts]

.5mm is very reasonable, and that falls well with trap amount for offset/lithography @133lpi. 

The classic rule to calculate trap amount is equal to half the diameter of a halftone dot. eg:  Divide 133lpi into 1 inch to get .0075" diameter of the dot. Divide that by 2 to get the suggested trap rounded to .004".  Your .1mm max tolerance expectation falls just under .004"

By @Mike_Gondek

Are you missing a zero Mike? 0.5 mm would be 0.04 in, x10 that.