Archived posting to the Leica Users Group, 2013/06/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Mark Rabiner <mark at rabinergroup.com> wrote: 50 MLux-hrs of exposure = how many units of real space time? > It is equal to 25 Wilhelm years or 5.7 years of a commercial gallery. > ... Do they look > just like microwaves with a bank of florescent lights in them?!?!? > Mark, of Aardenburg Imaging, is, I believe, targeting typical indoor lighting. I don't know the exact specs, but his many years as a scientist at the Smithsonian and in research projects with Wilhelm, among other things in his background, make him very knowledgeable about the spectral and environmental standards that are considered the most representative. > > I'm surprised more people don't have problems with these tests. I seem to > be > the only one who does. I think the tests are quite good with respect to light, but it's the accelerated aging and paper issues that are the "elephants in the room." It's easy to crank up the light, but speeding up time is a bit more of a problem. The accelerated aging standards do not, for example, cycle the humidity and temperature. Yet, those are what is going to tear apart the coated and laminated substrates due to differential expansion and contraction. I don't trust any coated substrate to last all that long. In the photo restoration work I've done, the very old papers have surfaces that are a mess -- lots of cracking, etc. I print on Arches un-coated watercolor paper for some purposes. I'd bet it'll last longer than any other substrate we have available to us. > A huge fan of carbon printing though and my instincts and intuitions tell > me > they they should last a good long time to make a normal selling price as a > silver print valid. But I just know that neither I or anyone else have no > way of really knowing that for sure. ... And may easily have no idea. > We always live with uncertainty, but to the extent there are data points and historical evidence, I'd bet on carbon on a cotton substrate as being the most likely to last. When tests like Aardenburg are carefully analyzed, I think the bottom line is that the carbon or silver images will last a very long time. The paper is what is causing the color changes and probably will limit the lives more than the image forming substance. So, with those top imaging substances, it's really all about the paper. In this respect, one huge advantage of inkjet printing is that we have a choice in paper. Also, very importantly, the inkjet print is not subject to the chemicals that the wet process requires. Even if the washing is perfect, the wet process papers cannot have buffering in them to guard against airborne acids. > > The hard reality is when we invest in a silver print we have a fairly > reasonable idea of what that kind of investment it is on the archival > aspect. The purchasers' perceptions of the archival nature of a B&W was always thought to be an important part of formula. I suspect most of us did our best to process our B&W prints to meet those expectations. In fact, we appear to have overestimated their archival stability. The light selenium toning was not all that effective (heavy sepia much better), and the airborne acids are more of a problem than we thought. > ... when we invest in a print done > with technology invented the day before yesterday we really have no idea. > That's the reality. Hopefully high quality tests like Aardenburg Imagine does will help overcome some of the disadvantages our modern digital prints face in the market. Shining a light on them and calling it 62.3 years I find deeply comical. > It's all relative. I think sophisticated testing and publication of the test results injects at least some relevant information and evidence into the discussion. We've made a lot of progress with this digital printing technology over the last 10 years. I keep my old silver prints more as reminders of that old technology than as good display prints. They usually can't touch the carbon on cotton versions I now print. Paul www.PaulRoark.com > > > On 6/7/13 1:53 PM, "Paul Roark" <roark.paul at gmail.com> wrote: > > > By the way, the silver print is no longer the top dog for archival B&W. > > Carbon is king. See the fade test data, below: (I'm not sure how the > > formatting will hold.) > > > > Aardenburg Imaging (http://www.aardenburg-imaging.com/) uses summary > > metrics that are probably not familiar to most. The "I* Color" measures > > the extent to which color has shifted. "I* Tone" measures only the Lab L > > (relative grayscale density) shift. Both of these are weighted to take > > into consideration human perceptual characteristics. The Delta-e, of > > course, is the familiar total color and tone (Lab A, B, and L) shift, not > > weighted by our visual perception characteristics. With the I* Color and > > I* Tone, the higher the score, the better. 100.0 is perceptually > perfect. > > With Delta-e, the lower the better. > > > > > > Aardenburg Imaging fade test results at > > 50 MLux-hrs of exposure: > > > > > > I* Color I* Tone Delta-e > > > > Ilford Galerie FB Silver > > > > Average 90.9 98.8 1.4 > > > > Worst 71.7 97.9 3.2 > > 50% test patch 94.8 1.0 > > > > Ilford FB selenium toned > > > > Average 92.5 98.8 1.2 > > > > Worst 75.5 97.4 2.8 > > > > 50% test patch 96.2 0.9 > > > > "Eboni" 100% carbon on Premier Art 204 gsm paper > > > > Average 100.0 99.0 0.3 > > > > Worst 99.8 97.7 0.6 > > > > 50% test patch 100.0 0.2 > > > > Note that this carbon ink sample is now at 120 Mlux-hrs, and the 50% test > > patch results are identical to what is shown, above, for 50 Mlux-hrs. (I > am > > the proud inventor of this inkset.) > > > > Paul > > www.PaulRoark.com > > > > > > > > > > > > On Fri, Jun 7, 2013 at 5:39 AM, Chris Williams <zoeica at mac.com> wrote: > > > >> Europe gets all the cool kids. > >> > >> http://www.ilfordlab.com/ > >> ... > > > > _______________________________________________ > > Leica Users Group. > > See http://leica-users.org/mailman/listinfo/lug for more information > > > > > -- > Mark William Rabiner > Photography > http://gallery.leica-users.org/v/lugalrabs/ > > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >