coating but not floating
Originally Posted by David A. Goldfarb
i have never coated a gel emulsion the way i mentioned -only gum variations and casien/albumin variations
i think you are right about the old mass production methods
unfortunatly your knowledge of rod coating is limited to the faulty 'pushing ' that is so common and only used to lay down sens sols-the road to hell is paved with good intentions
the identicolor process used a ss rod wrapped in wire
that way the dia of the wire determines the thickness of the emulsion-just like a notched trowel spreads mastick or stucco
very tricky but once you get it and understand it you can make a rod to turn out emulsion layers that are almost as consistant as machine coating
i paid the bills that way for some time and i can affirm that all the problems that you know re rods don't exist if you do it this way
i suspect that since i use supermkt egg substitute instead of fresh eggs my consisency in the actual emulsion mix is also more consistent then what you expect
no i won't tell-my emulsions are proprietary
i desribed the rod-but you should know that it is part of a patented/tmkd franchise and you should procede with caution if you hvae not payed for the franchise
tip: use a non stick griddle to hot press any surface that is cranky/sticky/fragile
vaya con dios
I wouldnt have thought that anyone would coat the albumen by anything other than floating. Its the silver stage thats less clear. I was just testing a sample so I used brushing to apply the silver nitrate but I think the lack of hardening probably made it less noticeable.
MASS PRODUCTION YOUR GOAL?
Originally Posted by Justin Cormack
mass production methods of 100+yrs ago would certainly work today
are you intending to make 1k+ sheets a day for sale?
the way i see it the albumin was really a size component to produce a glossy surface to put the silver based light sensitive solutions on top of
a sheet of rc projection photo paper that has been fixed with out exposure to light gives you a stable glossy gelatine surface that you can overcoat with any light sensative solution of your choice doing away with the albumin and getting to the issue of a light sensitve solution of your choice
albumin was the solution solution at the time to the problem of: how to get a consistant glossy surface-it went out of prodution because faster/cheaper/easier MASS PRODUCTION methods superceded it
paper coated with albumin and exposed and fixed is NOT archival-the albumin cracks and highlight staining allways takes place-that may be the real reason why it was superceded
i and many others love the look of it-but you can get the look without the problems
ex:: water color paper with a pure gelatine overcoat is available
if you want to mix the eggs and coat yourself fine-but are you trying to repeat the massproduction procedures of 100 yrs ago or are you wanting to create art?
rag cotton ink jet paper becomes an obvioius solution to many of these issues
if i want to coat 1 sheet with a gum/gelatine/casien/whatever quick and dirty, i pour a puddle and push/pull it with a fine tooth comb flip it onto a low heat non stick griddle and i'm ready to sensitise just like that
to learn how to push/pull sensetizer solutions with a rod get some coffee and practice on your support of choice sized your way-the color of the coffee gives immediate feed back on how even your technique is
i taught at the university leval years ago but i suspect that my students never revealed how they got the successful methods i gave them
vaya con dios
So how do you deal with the micro million bubbles that show up when you pull the paper from the albumen. How do you get a perfect coating?
Before coating, let the tray settle, then use a strip of paper to push the bubbles to the side of the tray.
I fold the edges of the paper along the two short sides to make two handles, hold the paper over the tray in a "U" and float it on the albumen so that the paper presses on the surface from the center out to the edges. Be careful not to get albumen on the back of the sheet.
I remove the sheet by sliding it out of the tray from the near edge and then letting it drip over the tray before hanging it. While it is hanging and wet right out of the tray, you can pop small bubbles and fill them in. Some people use a glass coating rod for this purpose. I always make an oversize sheet and cut it down, so bubbles at the edges aren't a problem.
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It's pretty much what I am doing but i still get some bubbles. I don't know where they come from. Maybe it's the air in the surface of the paper that gets pushed out by the albumen as it seeps in.
Maybe I'll try a few drops of darkroom surfactant to see what happens. I figured the first batch of albumen is for coating practicing, so no big deal.
Do you age the albumen? I haven't decided if this reduces bubbles, but it might help. It does seem to give the albumen a more uniform consistency.
It could be the paper, I suppose. I've used a few different kinds, but my normal paper is Strathmore 500 1-ply plate. A heavier paper might not spread as smoothly on the surface of the albumen, and a rougher paper might trap air bubbles, though rougher surfaces are also better at hiding flaws.
It might also be that the bubbles you are seeing aren't a problem. If the bubble is large enough to create an uncoated spot on the paper, then it will show as a flaw, but there might also just be air in the albumen that becomes part of the sheen, or tiny bubbles (with all respects to Bradda' Don, may he rest in peace) that go away as the paper hangs.
I haven't tried things like Photo-Flo in the albumen, but it might not be a bad idea. I know PE uses it to improve coating with gelatin emulsions. Let me know how it works, if you try it.
I just made some albumen so it is not aged. Couldn't wait for it to happen. My next batch is going to be made with egg white powder that I bought from amazon. I am going to make a large batch with the 8oz s that I purchased so that will give me a chance to let it age in the fridge.
I have ordered the Strathmore 500 1-ply plate but it is still on its way . So far I am using Photo Formulary baryta coated paper. It is a little stiff and it curls quite a bit but I like the surface and you can get gloss with the first coating. Will se how that works.
The albumen that I made was quite uniform in consistency. It just felt thick and gooey. I suppose that is the way it needs to be for it to make a good coating. It is just those damn bubbles. They are tiny and I can sometimes make them be outside the printing area but as you can imagine, I want to be able to make a perfect coating, or close enough so you are not distracted by them when looking at a print.
I will also try the puddle and fine comb, just for giggles. Who knows....
I also had the idea of making a coating rod with closet hanging rod and some magnet wire that I got from radio shack. I have three different gauges so it will be fun trying that.
The aged albumen feels a little thinner than fresh albumen. Fresh eggs contain two densities of albumen. Powdered egg white, which is what Daniel Levin uses, is very uniform.
If there is a paper that you would like to try for albumen but it seems to curl somewhat when coated,is there a way to flatten the paper without damaging the albumen?