Suggestions for eliminating mottling on uncoated stock?

[Kasplen]

When printing PMS 311 on an uncoated stock, its terribly mottled. On coated stock, it prints perfectly. I realize this is due to the high amount of transparent white in the 311 build.

We had our printer add opaque white, and that didn't help. Any other suggestions are greatly appreciated!

 

[gordo]

When printing PMS 311 on an uncoated stock, its terribly mottled. On coated stock, it prints perfectly. I realize this is due to the high amount of transparent white in the 311 build.

We had our printer add opaque white, and that didn't help. Any other suggestions are greatly appreciated!

Lay down a matte varnish first?

 

[tmiller_iluvprinting]

Is printing with UV curable ink an option? We find that this helps reduce and sometimes eliminate the mottle.
Regards,
Todd

 

[Alois Senefelder]

Mottle!

Mottle!

Hello Kasplen,

What you are seeing - IS paper mottle, 1) Ink, no mottle on coated paper but appears on

uncoated stock ? - Answer, get your printer to print same ink on other makes of uncoated stock

and see the results.


Regards, Alois

 

[Cameron]

Lay down a matte varnish first?

A bit of a side question.. we've had a hard time over the years with solid red prints on something like 100lb cougar cover.. the difficult thing is rub resistance after the fact.. have the ink specially made for extra resistance, but have heard you can use varnish to help with this? Generally we thought that it would just soak into the stock and provide no help.. Though you might be able to enlighten me a bit on this?...

And dont mean to hijack your thread Kasplen.. we found we were getting mottling more noticably on uncoated stocks, but in general it was happening a bit more across everythign.. the transfer jackets were the cause 100% for us.

 

[gordo]

A bit of a side question.. we've had a hard time over the years with solid red prints on something like 100lb cougar cover.. the difficult thing is rub resistance after the fact.. have the ink specially made for extra resistance, but have heard you can use varnish to help with this? Generally we thought that it would just soak into the stock and provide no help.. Though you might be able to enlighten me a bit on this?...

Assuming that you have enough impression pressure (not enough and you'll see mottle) - and assuming that the mottle is not caused by poor ink trap - and assuming that the problem is not moiré (the halftone screen harmonically beating with the texture of the wire side of the paper (in that case the mottle will not be random but have a measurable frequency)) sometimes the mottle is built into the paper itself. Basically the uncoated paper may have patches of higher and lower absorbency. If you place the paper over a light table you might see the difference in density/absorbency. An initial varnish won't seal the paper but can help even out the absorbency of the substrate.
I would also discuss the issue with your paper supplier, they may be aware of the issue with a specific paper and may be able to offer an alternative.

 

[Kasplen]

Thank you all. Very helpful!