How to limit the mottling effect with offset printing on kraft paper

[lexignot]

Hello,

I have a mottling effect when printing offset directly on kraft paper. My packaging supplier mentions this is because the paper is not smooth because it's kraft paper.

Below is a comparison of two boxes from two different packaging suppliers, with the same pantones, the exact same paper and both with offset printing. The thing is supplier A (with no mottling effect) is three times more expensive than supplier B (my supplier with the mottling effect). In addition to the mottling effect, there seems to be a "glossy" effect and the color rendering is darker with Supplier B, and I don't understand why.

Based on your experience and photos below, do you know what could be the causes of such differences?

Thanks in advance for your answers.

 

[namelessentity]

Are you positive supplier B is being honest about offset printing? Both of those look like they were digitally printed.

 

[bill kahny]

Hello,

I have a mottling effect when printing offset directly on kraft paper. My packaging supplier mentions this is because the paper is not smooth because it's kraft paper.

Below is a comparison of two boxes from two different packaging suppliers, with the same pantones, the exact same paper and both with offset printing. The thing is supplier A (with no mottling effect) is three times more expensive than supplier B (my supplier with the mottling effect). In addition to the mottling effect, there seems to be a "glossy" effect and the color rendering is darker with Supplier B, and I don't understand why.

Based on your experience and photos below, do you know what could be the causes of such differences?

Thanks in advance for your answers.


View attachment 292457

Buy from the printer A - you get what you pay for

 

[jwheeler]

I agree with @namelessentity ....looks like vendor B is using digital printing, not offset printing. Digital presses use a wax-like toner that produces that shiny effect, and often have issues laying down a solid color on textured stocks.

 

[lexignot]

Thank you @namelessentity and @jwheeler for your answers.

I think you're right, vendor B should use digital printing instead of offset, which would justify the price difference... Knowing there are two layers of a white under the artwork (dry trapping) for vendor B, there is no way the result is darker than that of vendor A, which has no white dry trapping. I will pay for a third party agent to check the production with Vendor B.

Do you confirm that the minimum production order for offset printing for packaging is usually 500 copies in total?

Thanks

 

[gordo]

There are different grades of kraft paper. Often you can see the mottling already there in unprinted kraft. If the papers in your samples are different stocks then that might be the cause. Talk to your paper supplier.

 

[lexignot]

There are different grades of kraft paper. Often you can see the mottling already there in unprinted kraft. If the papers in your samples are different stocks then that might be the cause. Talk to your paper supplier.

Hi @gordo thanks for your answer. Yes good point but in this case the paper is exactly the same, so it must be the printing machine and/or the colors used.

 

[sveibl]

Flash reflection in photos makes it tricky but shine on B makes me believe it has a better coating or smoother surface to print on.

If it is determined to be printed offset, I would reduce the line screen.

If its digital, all bets are off, but reduced screening and re-processing GCR/UCR may make it sellable.

Finale thought, you get what you pay for!

 

[DeltaE]

Hello,

I have a mottling effect when printing offset directly on kraft paper. My packaging supplier mentions this is because the paper is not smooth because it's kraft paper.

Below is a comparison of two boxes from two different packaging suppliers, with the same pantones, the exact same paper and both with offset printing. The thing is supplier A (with no mottling effect) is three times more expensive than supplier B (my supplier with the mottling effect). In addition to the mottling effect, there seems to be a "glossy" effect and the color rendering is darker with Supplier B, and I don't understand why.

Based on your experience and photos below, do you know what could be the causes of such differences?

Thanks in advance for your answers.


View attachment 292457

If I were supplier B, I would try to coat the surface with matt-coating. then the effect could be improved and close to "A"

 

[lexignot]

Thank you all for your answers.

Confirmed for supplier B, it was done with a Digital UV printer (I understand the Scodix digital press uses the UV printing technology?).

Questions:

1. Is it possible to print two layers of opaque white under the artwork using an offset printing machine? If so, is this possible with a Heidelberg 7+1 offset printing machine or a LITHRONE G544+1 offset printing machine, with a UV printing machine upstream to dry trap the two layers of opaque white then it goes to the offset printer to print the artwork on top of the dried white layers?
2. Given the low quantity of my orders (500-2,000 pcs) and my printing and paper specs, it seems UV digital printing with a Colex cutter or equivalent could be the best option for me. I understand with a Colex cutter I won't get the mottling effect like with the Scodix digital printer, correct?
3. All the packaging companies I contacted do not have a Colex cutter or equivalent, so I was wondering what type of companies use these machines: specific packaging companies, pure printing companies, others?

Thanks in advance for your answers.

 

[smalloffsetpressexperts]

Include your Offset Ink supplier also in your search.