That'll work. Also, given how much it's scaling back, perhaps EKCo has a surplus refrigerated delivery truck or two it would like to sell you at a bargain price.
Originally Posted by Photo Engineer
that is kind of funny curt -
Originally Posted by Curt
they told me that they were going to be in
the paper film and chemical business for the forseeable future
(when they consolidated their south american concerns)
then in 2 weeks they announced they weren't making paper anymore.
- it was a big-wig in rochester + PR firm on the west coast that i spoke with ...
Ես այլեւս չի պատասխանելու իմ էլեկտրոնային փոստով
եթե դուք պետք է ինձ դիմեք ինձ միջոցով իմ կայքը կամ բլոգում
I remember getting the first box of Type "C" paper in 1958 or so. It was deliverd directly from Rochester in a refrigerated truck owned and operated by Kodak. It was the Kodak green with the Kodak yellow turned up page logo that they used in those days.
Originally Posted by Sal Santamaura
Oh, most of you don't know this. In house Kodak vehicles are green and Kodak security uniforms and guide uniforms are green. This harks back to the old days when Kodak used a green and yellow trade dress.
I am new to all this, as preparing my own exposure material always seemed to me somewhat beyond the horizon. However, in these days I thought making myself familiar with existing and emerging possibiities could be wise, and, who knows, even creative.
I have no practical experience yet, and was only doing some reading in this forum - thank you, Photo Engineer, for getting engaged in this, it appears to me that your assistance is invaluable.
My following practical questions may seem a bit outdated by others, but if there are answers in this forum, I must have overlooked them. They are meant for me to understand the practical dimensions of such an enterprise:
1) how do you coat? I understand you mostly work with orthochromatic emulsions under redlight, but what is the physical procedure of coating? Just pouring on a leveled substrate? How do you spread?
2) on which substrate do you coat? Only glass, or also some form of acetate?
3) Are there problems with siver nitrate bought from a noble metal supplier?
4) I understand that active gelatine is not easily available in these days. Does the addition of the additives mentioned by Photo Engineer provide a substiture for this, raising the ISO to similar levels as with active gel.?
5) how do you "shred into noodles(?)", and wash? How complicated/sensitive is this procedure?
6) I think it might be very helpful not only for me, but also others if a corpus of available literature on the subject could be established. I would go to any length getting books/articles, also by international foreign lending via scientific libraries. I would think it is very necessary to get as much an overview here as possibile, and then see how the available information could get adapted to provate/household procedures/facilities.
The only literature I so far read on this is "primitive photography be Alan Greene", some 19th century literature available on the net from Stanford Uni. - but this is all pre-gelatine/film - and a book in German, I think it was by Eder.
I'll try to answer you as best I can.
1. Coating can be by brush, spray, dip or blade.
2. I use any hot press paper at about 100 pounds weight (IDK that value in metric) and also use uncoated baryta. You can coat on fixed out, washed outdated photo paper as well.
3. Analytical grade silver nitrate, which comes in flakes, is just fine.
4. You cannot add these ingredients (allyl thiourea for example) to an emulsion make but a better effect is gained by adding sodium thiosulfate pentahydrate at about 100 mg/mole of silver and heat treating as described elsewhere.
5. You can use a potato ricer on the cold emulsion, or you can use a knife and cut it into tiny pieces. It works just fine. You wash until the wash water shows no cloudiness to a drop of silver nitrate test solution (the kind used to test for fixation of paper).
6. The book "Silver Gelatin" is very very good, but assumes that you know that you should be using active gelatin. There is a paragraph devoted to this, but it is not sufficient to explain such a broad topic. It is out of print in the US.
The books by Baker and Wall are good starting points, but the books by Baker are far more modern and accurate than those by Wall. Eder was a well respected author at the time of Wall and Baker. I usually don't mention his works as they are harder to get in the English speaking world.
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Thank you very much for these answers.
Originally Posted by Photo Engineer
"blade coating" seems what you do. I'll have to learn about this.
I remember when I tried to prepare the base for an oil print, I distributed the gelatine on the paper with a comb. It worked nicely, but in good light.
I am surprised you use (white!) paper. Does this not create a lot of flare? It is film we talk about? (Though, after all, the first negatives were paper negatives!)
I assume that sodium thiosulfate helps to get speed. What about the gold salt? I read elsewhere that this is near essential.
Who is the author of "silver gelatin"? Do you mean the book by Reed and Jones?? I thought this was just about using "liquid light".
The book by Reed and Jones has an entire section on emulsion making.
I do coat on film support and glass plates. Film support is hard to come by and plate coating is rather messy and difficult. I'm learning though.
Gold sensitization is a good way to increase speed, but at the expense of contrast. I want to get high contrast first before I move on to lower it and increase speed with gold. Gold also increases the tendancy to fog during the final sulfur + gold treatment. You have to be very careful.
Blade coating is only needed if you wish to totally eliminate brush strokes, but it too has some pitfalls.
A question which continues to bother me, even though I will be able to start with practical experiments only in some time, is that of coating. Apart from that I am not quite sure I understand how blade coating functions, I have been thinking about my regular work of sizing paper with gelatine.
I do this with a foam brush after placing the wet paper on an even surface. When the gelatine begins to get stiff, I hang to dry. So far so good, but the paper after applying the gelatine develops round or oval bubbles every once in a while, particularly when I coat larger formats, which, if I don't succeed of getting ridd of them by gently lifting the paper, create visible uneven spots in the coating.
How do you coat gelatine on paper, particularly in difficult light or even in darkness? How do you make sure the paper stays absolutely flat?
And, how is it possible to coat gelatine on acetate, as it is done with commercial films? There is, for instance, overhead foil, but how does one make the gelatine stick?
The foam brush entraps bubbles in the gelatin and coats them onto the paper causing defects. You can get rid of them by the following sequence.
1. Filter the melted emulsion.
2. Degas the emulsion with a vacuum (optional)
3. Degas the foam brush by saturating it with emusion and then squeezing out the emulison several times under the surface of the emulsion to prevent entrapment of more bubbles. (or use another method such as a brush or tray dip)
I don't coat in total darkness. I avoid pan emusions for the time being.
Coating on acetate or estar requires a subbing layer to facilitate adhesion.
You will never be able to make a film with a brush or foam brush that has no defects. You can only do this by the dip method or the blade method. This has been my experience at EK.
Hope this helps.
Originally Posted by Photo Engineer
thanks for this answer. However, I think I expressed myself wrongly. You are absolutely right about degassing the foam, I regularly do this. The foam brush works well enough for sizing purposes, but I would bever dream to try to coat a light sensitive emulsion with it.
But, as I said, I coat gelatine on wet paper, because dry paper as i know it starts to buckle as soon as water - or gelatine - is applied to it, and this makes it impossible to distribute it evenly. However, I notice often enough that even wet paper lifts from the surface in a sort of flat, round, well, what I called "bubbles" of maybe 2 or three " diameter. This is not air cught in the gelatine, but paper, well buckling from the surface even though it is wet.
Do you see these problems also?
Blade coating works with an absolutely straight metal blade held at even distance from the surface to be coated, maybe be a wire wrapped round it at each side, right? I presume you have to move this slowly and regularly over the surface, maybe forward and back to or three times. ithink this is what I will try (I might try it even for sizing, if only just to get the feeling). But how to prevent the paper from buckling?
I cannot help thinking of dipping as a mess. I never liked this as a sizing method, either I got "noses" from gelatine running down, or, when I drew the paper over a round tube to sipe of surplus gelatine it got other defects, the gelatine gets cold, and, and, and...