In this Tutorial I will show you how to make a Basic Silver Gelatine emulsion from scratch. I will guide you step by step through the whole process including equipment, materials and many tips and tricks I learned on my emulsion making journey. It was invented almost 150 years ago and became popular to the point where we can find it in pretty much every analog light sensitive material. The first time I made photographic emulsion was a few years ago when I was starting to reproduce the mysterious Autochrome. That emulsion was much more complicated than the one we will be making today as it had to be panchromatic (sensitive to the whole visible spectrum). Emulsion we will be making is as basic as it gets following the 1880s recipe that was adapted to modern materials by Mark Osterman.
WHAT YOU NEED?
Starting with safety of course.
Make sure to protect yourself with safety goggles and latex gloves.
- 3 tempered glass beakers: one 400ml and two 150ml (link) (link)
- Smaller sized tempered glass or ceramic baking tray for chilling the emulsion (link)
- Magnetic stirrer (link)
- Crock pot (link)
- Thermometer (link)
- Precise scale (link)
- Measuring cylinder
- Big stainless steel mixing bowl that will be used for washing
- Stainless steel or plastic potato ricer that will be used for noodling the emulsion (link)
- Half a square meter of Nylon cloth (link)
- A large syringe of some sort. It’s important that you can control the flow and that the hole is not too big. I made an attachment for mine using some thin plastic tubing. I melted the end together and pierced a small hole thru with a needle. (link)
- Glass stirring rods
- Wire mesh strainer
- Ice to wash the emulsion
- Fridge to chill the emulsion
- Lightproof black bag that is big enough to fit the small glass baking tray mentioned earlier
- Lightproof container to store the emulsion (link)
- And you won’t be able to do all this without a dark room illuminated with red safe light
- 1 liter distilled water
- 10.5 grams potassium bromide
- 0.4 grams potassium iodide
- 12 grams silver nitrate crystals
- 21 grams gelatin (photographic grade is best, but you can use food grade) It should be at least 240 bloom. Bloom tells us how hard the emulsion is. The higher the number the harder it is when dried.
- 1 grain thymol
- 5 ml 95% grain alcohol
MAKING THE EMULSION
Before you start making the Silver Gelatine Emulsion get everything ready and try to memorise all 11. steps because the temperatures, quantities and order is very important. All of your equipment from beakers to potato ricer should be nice and clean so you don’t accidentally contaminate the emulsion.
“FIRST MELT” GELATINE
To make the Silver Gelatine Emulsion start by preparing the first melt gelatine.
Put 3 grams of photographic grade gelatin into a 500 ml beaker with 85 ml distilled water. Then wait for at least fifteen minutes so the gelatine becomes fully swollen and easily flattened.
Proceed with reserve gelatine.
Slowly add 18 grams photographic grade gelatin into a 300 ml beaker filled with around 80 ml of distilled water. You don’t want to put all the gelatine in at once because it will not incorporate nicely. Once you have all the gelatin in let it soak as much water as possible. How much water you need really depends of the gelatine you are using. Some will absorb less and some more water. Just make sure it is nice and moist. This”reserve” gelatin will be drained and added to the emulsion after the first melt.
While making the emulsion you shouldn be in a rush but rather make sure every step is done correctly.
DISSOLVING THE FIRST MELT GELATINE
Now that the first melt gelatin has swollen it’s time to dissolve it. Place the beaker in hot water bath or in my case I will use a hot plate of magnetic stirrer that will help to keep everything in motion while heating up. You should keep this solution at a constant temperature of 50C or 120 degrees F.
While you are waiting for the main pot to get to temperature you can prepare the silver solution by dissolving 12 grams of silver nitrate in a 300 ml glass beaker filled with 85 ml of distilled water. Heat this silver solution to around 120 degrees F (50 C) using a hot water pan or crock pot.
ADDING THE HALIDES
When all the first gelatine has melted and you reached 50C proceed by slowly adding first 10.5 grams of potassium bromide and then 0.4 grams potassium iodide. You will experience a small temperature drop but it is gonna go back up quickly.
If you are using the same thermometers, mixing rods… make sure to wash them before using them in another solution so that you don’t cross contaminate things!
Stir the solution until there is no gelatine or halides to be seen as they have dissolved completely. If you are working with a magnetic stirrer this is the time when you should turn it down to 300rpm.
EMULSIFICATION (combining the silver with halides)
When the silver solution has reached the same temperature as the halide solution go on and draw half of this solution into the syringe adding on the adapter I made from that plastic tube. We will incorporate the silver solution into the halides in exactly two minutes so I set my timer to 2min30s. I added additional 30s so I can refill the syringe with the other half. Once you have everything ready start the timer and slowly squirt the heated silver solution in a continuous stream while stirring the solution. This is where the magnetic stirrer comes in handy. Constantly watch the timer as you don’t want to be too slow or too fast. At 1 min mark your syringe should be empty so fill it with the other half of the silver solution and repeat the step.
As you combine the silver with the gelatin-halide solution you will see the two clear liquids change into a milky white silver bromo-iodide emulsion. At least this is how it looks like under red safe lights. It actually has milky yellow color to it
This is where the crystals are formed and their shape is determined by your controls from temperature to flow rate of the silver solution. Here we are not that precise and therefore we will get crystals of different shapes and sizes from octagons, cylinders, ts and so on.
After all the silver has been incorporated, its time to ripen the emulsion by maintaining it at 50C or 120 degrees F for 15 minutes with constant gentle stirring.
While the emulsion is ripening, you can begin draining all the excess water from the reserve gelatin. Add the reserve gelatin to the emulsios. At this point temperature will drop so wait until it comes back up to 50C and then start the timer set to 5min. This step is called the digestion as we need to wait until all the new gelatin is completely dissolved.
After 5min you can turn off the stirrer, take the magnet out, pour the Silver Gelatine Emulsion into the glass baking tray and carefully slide it into the black plastic bag. Fold the bag over to make sure there is no light coming in and slide it in the fridge letting it set for a few hours.
NOODLING & WASHING (Getting rid of potassium nitrate)
Once the liquid emulsion has stiffen to a hard jelly take it out of the fridge and out of the plastic bag. Scoop out the jelled emulsion with a stainless steel spoon and put it inside the potato ricer.
Place the nylon cloth over the wire mesh strainer and squeeze the ricer to create emulsion noodles. Let them fall into the center of the cloth. When you have noodled all the emulsion, gather the edges of the cloth and secure it with a rubber band. Now fill the big stainless steel bowl with distilled water and add in a few ice cubes. Take the emulsion pouch and soak it in this water first moving it around for 5min and then for additional 5min without agitation. Proceed this step two more times changing the water after each cycle.
After washing drain the silver gelatine noodles thoroughly for at least 15 minutes and then place them into a clean glass beaker. Start re-melting the emulsion in an electric crock pot at around 50C or 120 degrees F so we can add in the “finals.” To finish this emulsion off I am adding 5ml of 95% alcohol so the emulsion will run smoother and a grain of thymol, that is a preservative and will prevent the bacteria growth. Before pouring it into the storage container I also like to take a spoon and scoop out all of that foam that got formed during mixing. This is the first step of the bubble battle. After that just pour the emulsion in a light tight container, store it in the fridge and use it.
Voila we just made our own silver gelatine emulsion!
Before coating on the glass or paper I recommend you to add in some chrome alum that will harden the emulsion when dried and make it more resilient to processing. This fine grain emulsion is sensitive to blue, violet and ultraviolet light. Speed of the emulsion can vary from batch to batch but in my experience it is somewhere around ASA 1-5 range. To determine the speed I will test out this emulsion in the following days and share the results with you in the next week’s video. If you would like to learn how to coat the emulsion on glass follow this link.