COATING GLASS DRY PLATES – Step by Step Tutorial
In this blogpost I will guide you through the process of coating glass dry plates with silver gelatine emulsion. When I started coating my own plates I wished I had stumbled on a complete tutorial like this. I had a lot of different information from forums, blog posts, videos… All I was left with was to just start experimenting. Lots of emulsion has been poured with many failures along the way so here I am making a step by step tutorial without any secrets for everyone who would like to try out this magic. There are many commercially made emulsions available on the market from Foma, Liquid Light, Rollei…
If you would like to save yourself from all the work I also sell ready to shoot pre coated dry plates here.
Now let’s dive into the tutorial!
Commercially bought emulsions are usually stored in black plastic canisters just like mine. Main ingredient of all emulsions is gelatine which liquifies at higher temperatures above 30°C. This allows me to take the silver gelatine emulsion out of the fridge and stick it in a bigger plastic container filled with hot water. Like this emulsion melts slowly. You will maybe have to change the warm bath a few times to speed up the process.
What you dont want is the water being too hot (boiling) as this may damage the emulsion itself!
CLEANING GLASS PLATES
(Before you start make sure to put on some gloves so you don’t contaminate the glass while handling + for the safety later on)
While the emulsion is melting you can start cleaning the glass plates. I buy my plates from a local framing company which offers thin and good quality glass cut to desired size. Thickness of my plates is 1,8mm.
There are different methods to clean the glass. In my case I am cleaning them with a help of calcium carbonate, dish washing soap and water. I am adding them to the plate separately in this case but you can mix it together in a paste.
Place the plate on a flat non slippery surface and put a small amount of calcium carbonate on the middle of it. On top of it I squeeze a drop of dishwashing soap. Then take a piece of paper towel or ideally cotton tabs and start scrubbing in a circular motion. Make sure to clean the whole surface + the back of the plate. Handle the plate by the edges as much as possible!. After the whole plate is scrubbed you can clean the paste off with running warm water.
DRYING GLASS PLATES
Plates have to dry out before you coat them so after they are cleaned place them on a drying rack first for all the excess water to drain off (If you don’t have one they are available here.
Now that the water is drained take the plate and dry it with a help of paper towels. Make sure to dry it off completely. After you finish check if the plate is clean by fogging it with your breath. Fog should disappear smoothly. Place the cleaned and dried plates back in the drying rack.
How much emulsion do I need?
In my case I use around 1,5ml of emulsion per one 8x10cm plate. It depends of the type and density of the emulsion you have. You will probably have to make a few tests first. You can always just put too much emulsion on and then drain off the rest.
Different Ways to coat?
There are many different methods of coating.
- Pour the emulsion straight on the plate and coat it by tilting.
- Use glass rod or puddle pusher (Check out blogs from Denise Ross)
- Spin coating
I tried all of these methods but none of them worked as well for me as using a simple combination of tilting and syringe. Benefits of using the surrigne are that you can apply the emulsion slowly wherever you have a blank spot & you can just suck back in any bubbles that are often formed. It gives you much greater control than any of the other methods. Of Course you need to make sure they are clean of any contaminants before you start.
GET THE EMULSION READY
When the emulsion has melted take a small amount of it out of the tank with a syringe (maximum intake of mine is 5ml which is enough to coat a few glass plates). Squeeze out the emulsion in a small beaker which is sitting in a hot bath (I just put some warm water in a bit bigger beaker). This way emulsions remain liquid throughout the process.
COATING THE GLASS
- Get the cleaned glass plates ready
- Take around 2ml of the emulsion in the syringe and start coating the glass. The way you hold the plate is very important…
How to hold the plate?
Support it from the bottom on your fingers which allows you to tilt the plate and move the emulsion from one edge to the other
- Start applying the emulsion on the glass plate. I usually start in one of the cornes and then move over the whole plate. Make sure that everything is warm enough or emulsion won’t collaborate!
- While moving the emulsion around you can help yourself with the syringe filling in the blind spots.
- Once the whole plate is coated you must get rid of the excess so just tilt the plate on one of the edges and pour the excess back into the beaker. I usually drain off a few drops (not too much or the negative image will be too thin!). After you finish just wipe the back with a piece of paper so the drop that escapes doesn’t stick everywhere and contaminate everything.
HARDENING THE EMULSION
Place the plate on a totally flat and level surface for a few minutes for the gelatine to harden a bit. For this purpose I use a marble slab. Why? Because it is totally flat and usually much cooler than the surroundings which makes the gelatine to harden faster.
In the meantime you can coat other plates 😉
DRYING THE PLATES TO GET DRY-PLATES & STORAGE
After the emulsion has hardened plates can be stored in a light tight drying cabinet or even left on the counter if you have a double door in your darkroom. For this purpose I have built myself a special light tight drying box with a ventilator that can hold up to 5 8x10cm glass plates. This way I can turn the light back on while they dry. Ideally plates should be left drying for 24h. Next day dry plates are ready to store. Turn the Safelights back ON, open the box / cabinet and take the plates out. I store them in black lightsafe bags that I got from used papers & films. Before putting them in each of them is wrapped in an acid free waxed paper that prevents sticking.