Multilayer gum printing - adhesion

[walter23]

Where do you guys get bottles for storing stock solution? I've been trying to track down a 100ml brown bottle but no luck, other than a plastic cough syrup bottle the guy at the drugstore gave me. If only I still worked in a university lab...

 

[walter23]

Or would a plastic (brown) bottle work? I'm not sure if the dichromate is reactive against plastics.

 

[Loris Medici]

Walter,

Have you tried other drugstores? Maybe they can lead you to a retailer or sell some bottles from their stock? I buy mines from the chemisty store, usually in numbers of 10. (Since they're so cheap.)

http://www.57aromas.com/category/Amber
http://www.aquariusaroma-soap.com/index.php?cPath=34_58_197_250_62

 

[PVia]

Ebay, B&S, Photo Formulary all sell them in many sizes but sometimes you have to ask if it's not in the online catalog.

 

[glbeas]

I've heard of situations like this with UV cured printing processes. The curing process apparently changes the adhesion properties of the ink surface causing the next layer to not adhere to the first ink layer. In this case I wonder if there is some way to create more tooth on the surface of the first cured pigment layer so the next will be able to bond properly to it.

 

[donbga]

Thanks Katharine; appreciate the help.

For now I'll assume my first layer is okay and just try to sort out the second layer issue. I probably just made a bad batch of gum / sensitizer, it didn't seem to brush on right, and even a test print with just one layer of that batch didn't seem right to me (took a much longer exposure than normal).

Should find a brown bottle and mix up a bigger batch of sensitizer to keep it consistent and make proportions easier to control. Does the dissolved dichromate solution last any reasonable length of time?

IME, sizing the paper will make this problem as well as others go away. FAEW is an excellent paper for printing gum.

 

[walter23]

IME, sizing the paper will make this problem as well as others go away. FAEW is an excellent paper for printing gum.

Sorry, FAEW is? Fabriano arstisco <something something>?

 

[Loris Medici]

Walter, FAEW is an acronym for Fabriano Artistico Extra White. (There's also FATW -> Fabriano Artistico Traditional White...)

BTW, I've just noticed your statement: "...Should find a brown bottle and mix up a bigger batch of sensitizer to keep it consistent and make proportions easier to control. Does the dissolved dichromate solution last any reasonable length of time?..."

I hope somebody has already posted a PM to you that you shouldn't mix gum/pigment and dichromate beforehand; you have to add dichromate right before coating. If not, the solution will definitely go bad. Quicker in high temperature / humidity and light levels, slower in low temperature / humidity and light levels. If you absolutely need to mix and store the coating solution beforehand (I can't think of a single reason for doing that BTW...), keep it away from light (especially daylight or any other light which substantial amnt. of UV) and keep it cool (in the refrigerator). Even kept in optimum conditions, I don't recommend storing the premixed coating solution more than 1-2 days. Gum isn't like cyanotype or vandyke / argyrotype where you directly use the stock sensitizer solution, you have to compound/mix the solution for each print individually. (Or at least for each - short - printing session!)

 

[Colin Graham]

I'm not sure if they ship worldwide, but I've been using the amber plastic bottles with the flip up lids from specialtybottle.com for pigment/gum mixes as well dichromate for the past several months, no weird reactions so far.

 

[PVia]

Walter, FAEW is an acronym for Fabriano Artistico Extra White. (There's also FATW -> Fabriano Artistico Traditional White...)

BTW, I've just noticed your statement: "...Should find a brown bottle and mix up a bigger batch of sensitizer to keep it consistent and make proportions easier to control. Does the dissolved dichromate solution last any reasonable length of time?..."

I hope somebody has already posted a PM to you that you shouldn't mix gum/pigment and dichromate beforehand; you have to add dichromate right before coating. If not, the solution will definitely go bad. Quicker in high temperature / humidity and light levels, slower in low temperature / humidity and light levels. If you absolutely need to mix and store the coating solution beforehand (I can't think of a single reason for doing that BTW...), keep it away from light (especially daylight or any other light which substantial amnt. of UV) and keep it cool (in the refrigerator). Even kept in optimum conditions, I don't recommend storing the premixed coating solution more than 1-2 days. Gum isn't like cyanotype or vandyke / argyrotype where you directly use the stock sensitizer solution, you have to compound/mix the solution for each print individually. (Or at least for each - short - printing session!)

Loris, I think he meant just the dichromate solution...

 

[Loris Medici]

Loris, I think he meant just the dichromate solution...

Oh? If indeed so then disregard my post; I may have misinterpreted the original statement. Sometimes people use sensitizer and coating solution synonymously, that can be confusing.

 

[walter23]

Yeah, I meant the dichromate solution alone. I think I will have to size the paper, but I did find that I could get good adhesion of the second layer by applying about double the normal exposure.

 

[Katharine Thayer]

... I did find that I could get good adhesion of the second layer by applying about double the normal exposure.

Excellent.

 

[walter23]

I'll scan the results and post them sometime. Just need to get my scanner set up again (it's boxed up for moving).

 

[walter23]

Here you go. I just photographed these digitally, with uneven window lighting alas, and adjusted as best I could to match the prints.

Single layer:

Two layer:

Thanks for the help so far. I plan to work on this quite a bit more, I really like this technique.

 

[Katharine Thayer]

Very cool, thanks for sharing. I'm especially intrigued with the two-tone violet/ochre ones, but I also like the black and white. Very nice,
katharine

 

[walter23]

Now I just have to find time to do some more