Step 12: The blue layer: home stretch

Mixing, coating, registering, printing and washing should be old hat by now, but here's a refresher:

1. Mix your pigment: a gram cyan watercolor, 5 ml gum, 5 ml dichromate

2. Coat paper.  Smooth and slow, there, Pancho.  Coating screw-ups can not be undone, and at this point hours of effort are at stake. Perform this step in normal incandescent (non-UV) room lighting.

3. Hang to dry 20 -30 minutes.  Clean your stuff up.

4. Register red negative to cyan-coated layer.  RED negative to CYAN layer. Perform this step in normal incandescent (non-UV) room lighting.

5. Tape (remove pins) and place in print frame.

6. As a starting point, expose for 10% less than yellow layer: 54 seconds was used here.

7. Wash.  Wash.  Wash.  No cutting corners.  At least 30-40 minutes.

8.  Hang to dry.  Pat yourself on the back.  You deserve it.
This is a really fabulous instructable and your results are amazing. Great work! <br> <br>I do wonder, however, whether it's wise to wash dichromate, and indeed cadmium yellow, down the sink.
<p>Dichromates are poisonous, so it's definitely not a nice thing to add flush down the drain, but it's so diluted by the time it's rinsing off the print, I would think it isn't a huge deal. Perhaps more important to note is that potassium dichromate is an oxidizer (will add fuel to a fire), so you definitely should not throw it in the waste basket. Washing it down the sink with water is the safest thing for your home/studio. </p>
The amount of pigment is ridiculously small. Think of the millions of watercolorists out there using cadmium yellow and washing their brushes in the sink. We should probably concentrate our cadmium concerns on batteries. <br> <br>The dichromate I ride the fence on. Recovering the water from the first wash, which should be a gallon or two, for recycling would eliminate the vast majority of the dichromate from going down the drain. On the other hand, storing six gallons of water per print (and I usually work three at a time...18 gallons total) until I can take it somewhere, where it'll be treated by even more harsh chemicals...you get the idea. <br> <br>Thanks for your kind words.
<p>This instructable is really great, a lot less intimidating for a beginner than the article on gum printing on the website about alternative photography we all know (If you don't, you can spend ~10sec searching to find it). When I finally get around to try this, I don't think I will do tri-color right away, monochrome will be just okay (And I like monochromes).<br><br>I don't know, whether You are still active or not, but if You could make a similarly informative and easy-to-follow instructable on paper sizing, I would be thankful.</p>
Brilliant! <br> <br>Thank you SO MUCH for sharing this process. Your instructions are clear and well written, and the process its self is fascinating. <br> <br>I have even MORE respect for those early photographers, (Imagine lugging an old plate camera around Yosemite), where things could go TERMINALLY wrong at any of a dozen and one different points allong the road from taking a picture to hanging a finished print. Even understanding the chemistry only helps you SO FAR. <br> <br>I'm dying to give this a go some time. <br> <br>Might have to build a camera first... <br>
Great Instructable!!
It's just a wonderfull work, really really nice work. I love it. It reminds me the polaroid pictures. <br>The proces is a little bit similar to the three color screen print. <br>Probably i can't do it, but is a nice work, i will give it a try someday. <br>

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