Re: Paper mills adding more and more artificial brighters in the papers??
There are a few of options in regards to the predominance of brightening agents in papers....
1) Use UVcut filtration on both the measuring instrument and the lighting conditions to prevent the excitation of brightening agents. Possible, but perhaps impractical, as it would require all lighting conditions have their UV source cut.
2) Select papers, both proof and production, that contain no brightening agents, or at least limited agents and similar amounts between proof and production stocks. Both options are difficult, but possible. However, production stocks change frequently making this a moving target Another option with paper is to use the actual production stock ala the Whole Proof, which coats printing stocks for use with inkjet devices.
3) Use software compensation. ProfileMaker and the Argyl CMS (Heidelberg as well?) both offer the option to correct for brightening agents present in measurement data. These options rely on spectral, UV included measurement data. ProfileMaker limits this correction to the perceptual rendering intent only. Argyll's limitation is its command line "interface". Ideally both the proofing and the simulation profile would have the brightener correction made to them, and with standard measurement data like the SWOP, Gracol and Fogra data sets only containing colorimetric values, this may have limited usefulness.
Given the drive for cheaper/whiter papers, I don't think brightening agents will be going away. I think the best hope to lessen this issue relies in the use of intelligent software correction of the brightening agent's effects. and a stricter regulation of UV content of lighting conditions. Drafts of ISO 13655 and ISO 3664 are attempting to lessen the issues to some degree.