Paul,
I've been studying your pdf on EbVT and am finally beginning to get the hang of it. In my reading I learned there are two major color scales, CIE and Hunter. Can I assume you're working in CIE? What I read was that this protocol was more commonly used.
Noticed a small typo in the pdf - the second link's URL ends in "at page 6-7" and I had to delete that to get the link to connect. I'm sure most of your readers will have no trouble but there might be newbies who can't.
Any reason I can't go ahead and, if I can find those Canon carts locally, load my Y cart with your mix? I'm due for a new batch anyway. Care to divulge how you test for fading? I read about a procedure a while back (maybe it was yours) using a common reflector face down on the test print. The reflector had holes punched around the rim to lessen heating. I forget what bulb was used.
But wouldn't I still be faced with my LED gallery lighting issue? Crescent 2299 matches my Premier Art paper quite well... and under these LEDs, that's what shows up against my Spanish White board and Ilford MG paper. It's quite noticeable, more than 1 unit of B, if I understand the L a b language correctly.
Was pleased to see my submission way back is holding firm. Talk about newbies... I was still very green behind the ears. But I still have much to learn.
Paul
Message
Re: [Digital BW] Re: LED lighting in art gallery - some issues
2015-07-10 by Paul Roark
Paul,
The L, A, B scale I reference is the CIE version.
Thanks for pointing out the URL problem/typo.
You should have no trouble mixing and loading the toner yourself. The dilute version for the 1400 family, written up at
uses 90% clear base, version c6b. You can mix that, or just buy it from MIS. They sell it for a reasonable price. I'm not sure if Canon sells the blue Lucia EX pigs in a small cart. The main barrier to trying this is the cost of those two Canon carts. Note my comment in fn 12 about how I drain the Canon carts. I tried a syringe and it was going to be way too annoying. I'm sure there is a more elegant way than I use, but it works. Be sure everything is totally clean.
My fader setup is shown at http://www.paulroark.com/BW-Info/Fader-Setup.pdf . It pumps out about 22K Lux, which is high. This dries the samples and will give an artificially long predicted life compared to one where the humidity is at 60. To partially offset this I have the fader sitting in a tray of water. But, I don't predict longevity by dividing the MLux hours in the fader by the average home or office exposure. I'm looking at relative fade compared to samples others have tested. It's a far from perfect predictor, but it's better than nothing. And, even before the water bath became my norm, when I did this early on and a couple companies threatened to sue me, they backed off when they saw what I was doing.
I'm not sure how the toned carbon samples would look compared to your old Ilford prints. You will have a high degree of control of Lab B just via curves or profiles. Lab A is set by the mix. I used a light selenium toning for my silver printing. That raises the Lab A a bit. The target for the toner mix is a level Lab A for Arches and a slightly elevated Lab A for the inkjet papers. So, if you get your Lab B equated but you find there is a bit too much of a reddish cast, change the toner mix a bit by reducing the blue and increasing the cyan. If you mix just one cart full at a time, you won't waste much ink in experimenting. Rather than trying to mix such small amounts of the concentrate, mix each color down to a 10% Canon pigment + 90% clear base first, and in large enough quantities to be accurate. Then you can alter the color ratios of the already diluted colors and be much more accurate and consistent about it.
Ultimately, you should be able to match the silver prints so closely that no one will see the difference if they are under glass/acrylic such that the matte v. glossy finish does not show.
My understanding of the spectral responses of silver and carbon are that they are both relatively smooth. Where you get into trouble with matching is where both the light source and colors that make up your "gray" are not smooth. It's the interactions of the peaks in the response curves that shows up. I assume the mat board is a non-OBA board with a smooth response also. My memory of the Ilford paper was that it was a bit warm, which I also assume means it had no OBAs in it.
Good luck with the mixing. Let me know how it goes.
Paul
On Fri, Jul 10, 2015 at 1:48 PM, paulmwhiting@...m [DigitalBlackandWhiteThePrint] <DigitalBlackandWhiteThePrint@yahoogroups.com> wrote: