FOMA liquid emulsion - consistency + archival question

[elise]

Hi all - I've been using the FOMA liquid emulsion for a few months now – mainly working with printing on washi paper. I have two questions…

Firstly, regarding consistency. The accompanying leaflet says to melt it between 30 and 40 degrees, but I always find this too low. I go slightly higher to mid 40s, but still struggle to get a smooth result. I take the emulsion out of the fridge a few hours before, and use a thin plastic bowl in a water bath, stirring continuously with a plastic spoon for a long time. I can't get it perfectly smooth. It feels like I'm spreading out a cottage cheese with the occasional lump. I use a Japanese hake brush to paint it onto the paper, which helps to get rid of the lumps, but would love to get some tips to get a smoother consistency.

Secondly, my end result piece is a liquid emulsion on washi paper, which I then mount on artist wood board. I don't want to frame this behind museum glass as I want the texture of the paper to be visible. However, does anyone know how to make this archival? Is there a way of matte varnishing that also protects against the fading of the silver gelatin? I struggle to find archival information about liquid emulsions on paper other than traditional silver gelatin framing behind glass.

Thanks for any tips!

 

[Daniel Stuefer]

While I don't use the foma emulsion (but make my own), I usually just use hot tap water to melt it (starts off at around 55°C, and cools down over time), or around 45-50°C when I use a tempered water bath.

I only get lumps when the emulsion cools off too quickly again (when coating plates) on my (room temperature) glass plates.

So, in short, heat it up more, the emulsion should be able to take it as long as you don't repeatedly heat and cool the same bit of emulsion (take out just what you need out of the bottle, don't melt everything).

 

[koraks]

@elise, as to archival properties, liquid emulsion is really no fundamentally different from regular silver gelatin papers. The mechanisms of potential deterioration are the same. The physical makeup of the print does influence this, however.
The main issues you're combating against are:
1: Attack of the silver image itself by pollutants in the air or nearby materials (including the print/paper itself)
2: Deterioration of the gelatin binder
3: Degradation of the paper

As to (1), you can avoid most damage firstly by proper fixing and washing. Use a rapid fixer and an archival wash. The fact that you're using a very thin paper is to your advantage here; an archival wash procedure will be very effective. Make sure that the materials in direct contact with the print are intended for photographic archival purposes. Check with the manufacturer's documentation of the materials you use. This will also ensure protection against (3), assuming you're using a good-quality paper to begin with.

Since your print will effectively be exposed to the air as well as potential mechanical damage, the influence of e.g. sulfur compounds over time may be an issue. You could consider archival toning with selenium, gold or a modern variant of Sistan - although I'm always a bit skeptical about the supposed 'archivalness' of any toning that's not taken to completion. Still, it won't hurt. Sepia toning will work, too, but selenium and gold are a bit more subtle, color-wise.

Concerning (2), this is of course a bit of a challenge with the artwork being physically exposed. Storage/viewing conditions are the most relevant here; try to avoid overly high or very low humidity. Try to keep the print away from direct/intense UV light (esp direct sunlight); while this doesn't do much with the silver image as such, I suspect it can affect the gelatin.

Overall, as long as the print is treated as the delicate object it is, I don't expect major problems, to be honest.

I can't really help you with the first question, although I'd be inclined to just melt it at a higher temperature. I don't see how this will adversely affect the emulsion. Temperature control is very critical during production of the emulsion (esp. the process of ripening that controls silver halide particle growth), but that's handled by the manufacturer.

 

[Peter Schrager]

Ive used Golden brand satin polymer varnish w/UVLS to coat my pop prints. It's a acrylic varnish with UV protection.
I offer no clue as to archival longness but it certainly can't hurt.

 

[richyd]

I used Foma emulsion a few years ago to create dry type tinplates. I searched wide on various forums and got several tips and also learned from practice that the temperature during the whole coating process has to be maintained.

The tip above about just heating a small quantity for the job in hand was the first.

To keep the elevated temperature during the coating process I pre-heated the plates, some type of heating plate or pad would be useful. I used a small hair dryer. Perhaps doing that with the paper would help. If you are coating using a brush and that is at room temperature then I guess the loaded emulsion could cool to the gel state during the time of brushing process. So, maybe dip the brush in hot water and shake off excess before loading.

 

[Reginald S]

I haven't had problems coating sheets of 30x40cm with Foma's emulsion heated up to 40degree celsius because at first I bought a thermostat box with two thermometers whereas one thermometer sticks into the emulsion's waterbath.
Just as an example: https://www.terraristikshop.net/technik/steuerungen-terrarium/exoterra-thermostat/

Slight but undesired problems started with coating bigger paper. I would successfully like to coat Bütten paper of 60x80cm so I have bought mats which are designed to keep the reptils feed warm ( I don't have any reptil, but..):
Again just as an example: https://www.terraristikshop.net/tec...xoterra-heat-mat-terrarium-substratheizmatte/

The mats have to keep the paper warm, maybe 25 to 30 degree as a first idea.
That's the reason for the second thermometer connected to the thermostat, both keeping the temperature on a constant level.

Now I have to try either acryl glass or normal glass between heating mat and my paper.

Because of beeing a lazy printer, later I would love to build a coating machine, so I probably will buy a thick glass plate as a coating base..