On Aug 10, 2014, at 11:24 AM, Robin Myers <robin@rmimaging.com> wrote:
Thanks for the link to the NIST site. That saves some work looking up emission lines in my old copy of the CRC Handbook of Chemistry and Physics.
My pleasure! Don't overlook the option to generate vector-based line identification plots, which you can easily plop as smart objects in Photoshop on top of sample spectra. The tabular data would lend itself well to photorealistic recreations of spectra, if anybody was interested in such.
If someone is not very mechanically inclined, I recommend a cheap spectroscope such as the Hand-Held Spectroscope ($10.95) or Pocket Spectroscope ($52.95) on the Educational Innovations (http://educationalinnovations.com). From Edmund Scientifics there is the Spectroscope ($1.95) (http://www.scientificsonline.com/spectroscope.html) or the Desktop Spectronomy Kit ($49.95) (http://www.scientificsonline.com/desktop-spectronomy-kit.html). I have found such devices useful for some color seminars.
Good options. I'd only note that the technical skills to create a spectroscope are well within the arts-and-crafts abilities of schoolchildren -- but, of course, not everybody has an interest in futzing around with scissors and glue. Plus, an handmade spectroscope is unlikely to be as sturdy as a commercial one unless you put a bit of work into it.
Tyvek is also available with an inkjet printer compatible coating, but the company that makes this (I believe it is Dupont) used an FWA in the coating. It has a nice smooth matte surface, but is useless as a white reference.
Canon sells a Tyvek-backed banner paper with the exact same coating they use for the "Heavyweight Coated" paper they ship with large format printers for initial setup. It's actually superb for its intended purpose. You're right that the coating makes the top side useless as a white reference...but the back side is uncoated. It's got a bit of gloss and texture to it that limits its suitability as a general-purpose photographic white reference to situations with carefully-controlled lighting, but it's only an hair's breadth away from Spectralon in terms of its spectral response. Another great alternative is tear-proof envelope mailers made of Tyvek, available at pretty much any office supply store. It's also a popular material for CD envelopes.
Also, do not over-estimate the usefulness of FWA/OB agents for papers. Due to light exposure and chemical processes these agents can fade rapidly (days to weeks), resulting in a yellowish substrate and rendering their purpose moot.
Oh, no doubt. FWA is about the only thing that makes cheap office paper useable, and Hahnemühle in particular makes some truly fantastic fine art papers with subtle and highly effective applications of FWA; other examples abound across the rest of the spectrum. But, as you note, all these papers have limited lifespans and are not at all suitable for archival work. For something you know only needs to make it though the current season, maybe a bit longer in some cases, FWA is a fantastic option to have available. But if you want your children to see pretty much the same image as you yourself printed, FWA is guaranteed to prevent that.
There are some very white (CIECAM02 bc value < 1) papers available on the market. I have a list of papers without FWA/OB agents on my website at http://rmimaging.com/information/fine_art_paper.html. The CIECAM02 J, ac, and bc values for the papers are listed in the table.
That's a wonderful reference you've put together -- thanks! I'll definitely turn to it the next time I find myself looking for "go-to" papers (which, with luck, won't be for a while, of course). A few notes about some specific papers on that list: Canon's Fine Art Watercolor was, for a while, my absolute favorite paper. With an exception I'll note in a moment, it's got the highest L* value and the most neutral a* value, though the b* makes it slightly yellower than average. More importantly, at least on my iPF8100, it's got the largest gamut of any matte paper I've used. Its biggest downside is a strong tendency to curl. However, several months, maybe an year, ago, it seemed to be out of production. Nobody had any in stock with no indication that more would be on the way. I bought what I thought might have been the last 44" roll on the market. But I see it listed in stock at a couple places today...no clue if they're making it again, if these are the last few rolls from a forgotten shipment, if it's a reformulation, or what. Next, you list Canon's Tyvek Banner as being as close to perfectly white as it gets in the real world. I'll bet you a cup of coffee or other suitable beverage that you got that reading from Canon's swatch book...in which the sample they included lacked the "Heavyweight Coated Paper" coating. If so, grab a sharpie and make a mark on the sample, and you'll see why coating is necessary. Ink -- and especially Canon printer ink (ask me how I know this) spreads and pools on uncoated Tyvek like you wouldn't believe. Still...imagine a formulation of Tyvek with much finer fibers so the grain isn't visible, and a clear inkjet-accepting coating, and you could well wind up with the ultimate for-display fine art paper. It wouldn't have the luxurious feel of an heavy cotton paper, but prints could potentially be spectacular (depending greatly on the coating, of course). On your chart, ignoring canvas and proofing and other specialty papers, it looks like there's a several-way tie for second place, and the Crane Museo Portfolio Rag might have the edge. I can report that it's as good a paper as you can buy. Within rounding, its gamut is the same as the Canon Fine Art Watercolor, though the Canon (assuming it's still the same) might have an imperceptible edge. The Crane feels much better in the hand. The Crane has the same coating on both sides; Crane tech support says this is to control curl and makes no guarantees about what sort of printing the back side is capable of, but I can't see any difference in prints front or back -- and, it de-curls beautifully, unlike the Canon. All together, the Crane is a superior paper to the Canon, except for prints that will be spray-mounted and never handled. Last, I don't notice any of the baryta-coated and similar semigloss papers on your chart. In my experience, save for the Hahnemühle offering, all are OBA-free or have minimal OBA levels, are very bright and neutral, and have excellent gamuts. I've personally settled on the Canson Platine Fibre Rag. Its gamut is just imperceptibly smaller than those of the competitors, but it's perfectly OBA-free...and the paper itself is much more luxurious than anything else and printable on the uncoated side. If you get a chance, you might want to consider adding some of these papers to your guide. Cheers, b&