Good percentage to make process blue - NON REPRODUCING

[pacart]

I am making graph paper sheets and our client asked for a non-reproducing blue graph. I've never done this before, my assumption is all I need to do is get the screening right on the process blue, I'm just not sure what the percentage should be.

I don't want to print a bunch only to have the blue show up on photo copies.

thanks for any help that can be offered.

[gordo]

I am making graph paper sheets and our client asked for a non-reproducing blue graph. I've never done this before, my assumption is all I need to do is get the screening right on the process blue, I'm just not sure what the percentage should be.

I don't want to print a bunch only to have the blue show up on photo copies.

There are two issues here:

1) Is the color (blue/cyan) of the ink visible to the copier light? If it is then the copier will reproduce it. Modern photocopiers "see" cyan/blue so they will reproduce it. The notion of non-repro blue is not applicable to modern copiers/scanners.

2) Is the resolution of the copier's sensors high enough to reproduce a fine screen? There are no guarantees. If, for example you make your graph paper using a 175 lpi 10% screen (any color) then some copiers will be able to reproduce it, some will reproduce it as a patchy graph, and some will not "see" it and therefore can't reproduce it.

In short there are no guarantees of non-reproducability.

If you do not use a PMS ink to make your graph lines but choose to halftone screen them then you will have to be careful about the lpi to line width relationship otherwise you will get artifacts in the lines (ribboning, line width variations, etc.)

IMHO you need to run a press test to figure out the specifications. Even so you will not be able to guarantee performance (the graph won't reproduce) to your customer.

best, gordo

[pacart]

There are two issues here:

1) Is the color (blue/cyan) of the ink visible to the copier light? If it is then the copier will reproduce it. Modern photocopiers "see" cyan/blue so they will reproduce it. The notion of non-repro blue is not applicable to modern copiers/scanners.

2) Is the resolution of the copier's sensors high enough to reproduce a fine screen? There are no guarantees. If, for example you make your graph paper using a 175 lpi 10% screen (any color) then some copiers will be able to reproduce it, some will reproduce it as a patchy graph, and some will not "see" it and therefore can't reproduce it.

In short there are no guarantees of non-reproducability.

If you do not use a PMS ink to make your graph lines but choose to halftone screen them then you will have to be careful about the lpi to line width relationship otherwise you will get artifacts in the lines (ribboning, line width variations, etc.)

IMHO you need to run a press test to figure out the specifications. Even so you will not be able to guarantee performance (the graph won't reproduce) to your customer.

best, gordo

That is what I was afraid of. But you brought up another good idea that I didn't think of, using a pms color.

[bgardner]

Have you called your ink company? They make a Non Repro Blue Specifically for this.

[gordo]

Have you called your ink company? They make a Non Repro Blue Specifically for this.

The application of Non Repro Blue that you're referring to is not the same as the application in the original question.

For example, Non Repro Blue is used in comic art where an initial sketch is done and then inked over with black ink. The Non Repro Blue allows you to scan the image, separate the Non Repro Blue from the black art and then delete it. This is similar to the use of green or blue screens for special effects in moviemaking.

The OP wants an ink that copiers can't reproduce. That is a different application and one where the use of Non Repro Blue will in most cases not work.

Best, gordo