Oil print question

[Kami-the-Trout]

I've been playing around with oil prints for fun, and have a question.

I've been coating watercolour paper with Knox gelatin, brushing on 3% potassium dichromate and contact printing 4x5 negs under UV.

My first question -- how do you know what the proper UV exposure is? I've exposed negs from six to 12 minutes and can't see any difference in the matrix that comes out.

There is a faint brown image on all of them, but I can't see detail in them, until I start to ink them up, after which details starts to emerge. I'm not having a lot of success inking yet ( I didn't expect to), the ink seems to smudge up pretty heavy in the dark parts and muddies up in the highlights. There is an image there, but it's not very good.

Am I overexposing the matrix, or underexposing? How can I tell?

As well, after brushing on the potass. dischrom solution, the book I have says the paper becomes light sensitive as it dries. Is the drying print sensitive to ALL light, or just UV? I'm used to the other alt processes that allow us to work under faint tungsten. Is that a bad idea when drying oil print paper?

Any help greatly appreciated.

[Toffle]

You might want to ask Marianne (Mayfair710). She has been doing some stunning oil prints lately, though what she describes sounds much different from what you are doing.

Cheers,

[Dana Sullivan]

Knox gelatin might be too soft. It's around 100-120 bloom hardness, where a typical photo grade gelatin is around 250 bloom. The harder gelatin might offer more 'bite' for the ink.

You most likely won't see much more than a faint ghost image after removing the image from the UV box. I don't know about exposure times, though.

I've heard that oil prints can benefit from a half tone screen of 150 dpi +/-. Apparently breaking the image up into dots will also help the ink adhere, because you're giving it a lot of sharp edges to work with.

The dichromate-coated paper is more light sensitive than say a cyanotype or platinum/palladium coated paper. You may be experiencing some fogging using tungsten lighting, so try to dry your paper in the dark. A safelight isn't really necessary, just try to limit the sensitized paper's exposure to light as best you can without being too crazy about it.

Hope that helps.

-Dana

I've been playing around with oil prints for fun, and have a question.

I've been coating watercolour paper with Knox gelatin, brushing on 3% potassium dichromate and contact printing 4x5 negs under UV.

My first question -- how do you know what the proper UV exposure is? I've exposed negs from six to 12 minutes and can't see any difference in the matrix that comes out.

There is a faint brown image on all of them, but I can't see detail in them, until I start to ink them up, after which details starts to emerge. I'm not having a lot of success inking yet ( I didn't expect to), the ink seems to smudge up pretty heavy in the dark parts and muddies up in the highlights. There is an image there, but it's not very good.

Am I overexposing the matrix, or underexposing? How can I tell?

As well, after brushing on the potass. dischrom solution, the book I have says the paper becomes light sensitive as it dries. Is the drying print sensitive to ALL light, or just UV? I'm used to the other alt processes that allow us to work under faint tungsten. Is that a bad idea when drying oil print paper?

Any help greatly appreciated.

[holmburgers]

Anyone here experimenting with oil prints? At the moment, I just want to ink of some dichromated-gelatin matrices; not yet wanting to fiddle with bromoil or transferring the image.

I've got Sumi ink and Calligrapher's ink, any idea if either will work? Are they oily enough?

Cheers!

[gandolfi]

wow - a lot of questions, impossible to answer....

KAmi: it all depends.... on the density of the negative - the distance/power of the UV light - how many layers of gelatine - and so on...

you have to test this.. 4x5 isn't big, so make different exposures on the same negative (motive) - then you'll see...

Dana: drying in darkness is good, but be aware of the "dark process"... don't wait too long before using the matrix - it will harden slowly - also in the dark..

Contrast can somewhat be controlled when inking the image - softer ink: more grey tones - harder ink: higher contrast..

Holmburgers: test the colours - I have sometimes bought impossible oils - sometimes perfect... it is never easy to know before trying.... (but as a thumb rule I would say that lithographic oils are easier than "normal" oil colours...)

And why would you "just want to ink some dichromated gelatine matrices"?
My experience is, that this is much harder than making bromoils!

[David Hatton]

Hi,
This was passed on to me by an expert - and it works. Get a nice strong paper, I use Fabriano 50 300 lb. Three coats of 5% gelatine - the first one may benefit from a little hardener but I found not strictly necessary. Take a soft brus - Hake I use - and flood the paper with pottasium dichromate about a 6 or 7% solution. Get plenty on the paper and keep brushing until most or all of the chemcal is absorbed by the gelatin. Leave to dry. Expose under your test neg for about 3 - 4 mins. You should see a pretty good brownish printout after exposure. Rinse well with water to get rid of the dichromate and allow to dry out completely. This sounds daft but once dry, soak it in water to swell the gelatine. Pat dry to get excess water from the matrix. You may have to re-wet the matrix as your oiling progresses. For this process the oil pigmet needs to bee really stiff/tacky. You can buy stiffeners but better to use a stiff oil. After that all you need to do is roll on/off the ink until you have a masterpiece..Easy innit!

[David Hatton]

I've got Sumi ink and Calligrapher's ink, any idea if either will work? Are they oily enough?

Sorry, they won't work at all. You really need litho ink.

[holmburgers]

Hey thanks much guys.

David, that sounds nice & easy! And to also answer gandolfi's question, the reason I want to just ink up some DCG matrices is because I will have some excess matrices for my dye-imbition experiements, and I don't want to go out of my way to buy the right paper, buy the chemicals for the bleach, etc.

All in due time, but I was attracted to how simple the classic "oil" process sounded.

Also, I'm completely new to inks, oils, everything regarding graphic arts in this manner. I don't even know what lithographic oils are let alone what's "normal"!

edit: ahh, beat me to it... thanks David.

[gandolfi]

a word of warning! ;-)

If you think it is easy, then beware of the oilprint God's (and later the bromoil God's..).. They will slap you so hard!

about the oilpaint: You dont need the litographic inks.... (made for printing) - you can use oil paint (made for painting), but as I said - some work like a charm - some not....

David said: "You can buy stiffeners but better to use a stiff oil."...

yes and no - even when using lithographic ink, it is (in my experience) not still enough!
I always use ex magnesium carbonalt - a powder you can mix in the ink to make it stiffer. Also because you - as said - can alter contrast with the stiffness of the oil...

again: simple doesn't always mean easy....

[holmburgers]

Well, I'm an atheist, so I'll give it a go and see what happens. Maybe it'll convert me!