Liquid Emulsion Quantities?
I've just bought some Silverprint SE1 emulsion with the intention of coating cotton sheets. I'm aiming for a 5x7" image and was wondering how much emulsion I should be using per sheet as I only want to coat about 4 sheets at a time? I intend on using a brush if that makes any difference.
A ballpark figure would be fine, I just have absolutely no idea where to start as I don't want to mix too much and waste it or too little and no be able to coat enough sheets.
Not knowing the emulsion, reason would seem to dictate that the emulsion, depending on viscosity, would soak thru onto any type of backing material. I would start with a very small quantity as a test onto a piece of sheet to see the bleed thru and how large an area it might cover. Since a brush will always absorb a certain amount of any liquid without being able to apply it at a desired coating thickness (think of painting with a brush) maybe try a small artists brush and dip it into a shot glass? I'm wondering if a taunt sheet in the vertical might also prevent waste. (Just some thoughts.)
Use a spoon to get the emulsion out of its container (in safelight) and put it into a bowl in a pot of hot water -- I use one of those electric water boiling things with an open top. Melt 2-3 tablespoons of it and see how much that coats -- it'll probably do 4 sheets. If you need a touch more, it's no problem to melt a bit more.
The only thing you don't want to do is to keep heating and re-heating your whole jug of emulsion. I usually divide mine up into black plastic 120 film containers when I first get it. One of those filled with emulsion is enough to do 10 large sheets or so, the way I coat.
I think the 2-3 tablespoons Jeanne suggested, is a good start. I usually get out 1-1.5 normal spoon for 6 sheets of A3 size papers. With spoon I mean a big 3D hump on top of it. I leave the math to you to calculate how that translates to your situation. However, also be aware you may need to coat a second time (with inbetween drying) to get an acceptable coating with not to much brush strokes.
If you don't have an electric device for heating, don't worry: I don't either, I just use one of the developer type trays and fill it up with hot water (about 50-60 degrees). It will last long enough to allow you to coat one session.
From my experience it seems that about 6 - 12 ml of emulsion covers 1 sqare foot, but this depends on the gelatin and silver content and the porosity of the paper. If the emulsion is too viscous, dilute it with distilled water.
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Originally Posted by Jeanne
I have been using this SE1 for years, so here is my experience.
If you use a spoon - be sure it isn't made of metal!
use a plastic knive or spoon - or wood. that will be safer..
about the melting - re cooling.
I've actually done just that for years, without any problems.
also - the emulsion melts from outside towards the middle, so if you put the black bottle in running hot water for some minutes, some of the emulsion has melted, but not all.
The consistance of melted SE1 is like cream. and it goes a long way.
if you pout your amount up in a plastic "cup" (in safelight) - standing in hot water (to make it stay liquid) and then not using all of it - then you can pour the leftovers back to the can..
(at least I can.. depends on how contaminating your choise of surface is)
one coat of SE1 is enough.
I have been using a stainless steel spoon without issues. I have seen this warning before, but what is actually supposed to happen if you use a metal spoon? Is the problem iron / rust getting into the emulsion and what does it do, how does such contamination show up?
Last edited by Marco B; 05-12-2008 at 02:19 PM. Click to view previous post history.
Thanks for the info everyone, I feel a lot more confident about trying this out now. Hopefully I should get a coating/printing session in sometime this week/weekend so we'll have to see how things go.
I'm thinking of trying liquid emulsions soon. On paper like Weston Diploma or COT 320 is it best to use coating rods/ brushes or use the pour on method?
I don't think the method used for coating is so much paper related, as based on personal taste. I like brush strokes, and don't have a coating rod, so it's set...
However, I have my doubts about simply pouring the stuff, unless you are prepared for a pretty mess. Pouring will probably cause a very uneven thickness of the coating, which may cause all kinds of trouble later one, for example the emulsion coming loose from the underground in thick parts of the coating during wet processing or washing, creating uggly bubbles that are difficult to cure, and uneven drying.