Dot gain test sheet layout

Ben

Member
What is the best layout for a dot gain test sheet. I made one myself but i have pretty big difference in dot gain between the front and the back of the sheet.

In the 40% tone for some colors the difference between the front and the back can be 6 or 7%.

Can the layout effect these numbers? Attached the layout i use.
 

Attachments

  • Meetvorm_iSis.pdf
    2.1 MB · Views: 177

Ulrich

Well-known member
front and back is right? (and not bottom and top on the same side...?)

may be you are measuring the front before you have printed the backside? Try laying down a black sheet under the the print and calibrate your tool again on each side...

Ulrich
 

SteveSuffRIT

Well-known member
Are you are questioning variation from gripper to tail?
Screen tints should be adjacent (near) solids because TVI includes a solid and screen tint measurement.
So also check SID solid ink density "fall off" around the cylinder too.
Ramps should be vertical or around the cylinder, as you have done.
Steve Suffoletto
 

gordo

Well-known member
Am I seeing this wrong?

Test form.jpg


No 100% K only? Why?
 

curiosity

Well-known member
Ben,

That black stripe is whack, and should be fixed if you continue to use this form, but imo, your test form does not allow you to analyze the entire sheet proficiently.

Often times, test forms don't necessarily reflect any typical press run. For example, the average amount of coverage per key, per ink channel. Most test forms I've seen have too much coverage throughout. For that reason (and others), I've created this file, because it approximates per channel coverage a little more realistically (up for debate, for sure, but typically I see 20-30% coverage from lead to tail, per key, per channel on average). I also like its simplicity, even though there are occasions where I need additional targets added to the set. That said, of course, on any given set sent to press, TAC will vary a lot. But that doesn't negate the usefulness of this test form.

We then multiply this file many times up, without any other files, throughout a set. It allows you to measure solids pretty darn close to where you can measure TVI. It's also pretty good at revealing possible issues at press (i.e. chatter, phase, slur, etc.).

Give it a try or use something similar. You'll "see" things more clearly, as has been my experience.
For example, I like to keep SID from lead to tail within 5 points and consistent from left to right.
And if I ever measure TVI fluctuating greatly, I might discover slur, dot doubling, striping issues or gripper issues as the cause.

Although my comments are only a brief summary of a more complicated process, I hope this helps if even just a little.


universaltest.jpg
 

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