Making your own remjet remover
An important piece of the puzzle for developing ECN-2 films at home
Some of the chemicals used in the preparation of the remjet remover are dangerous, due to their caustic nature (sodium hydroxide) or apparent carcinogenicity (Borax). Always be careful when working with chemicals and make sure to take the proper safety precautions, such as wearing gloves and eye protection.
I take no responsibility whatsoever for any damage you may cause to yourself, others, or property when following the instructions below. With that said, I believe that with proper safety precautions the preparation is safe, at least to the same extent as darkroom work in general.
These instructions come without a warranty. The solution described may work for you, or it may not. Given that Kodak (the manufacturer of Vision films) provide the formula in their official documents, one would expect it to work properly without damaging the film, but I provide no guarantees as to this.
Remember that the decision to take on any project ultimately rests with you, and as such any consequences (good or bad) will be yours to bear.
Now that budget films such as Kodak ColorPlus and Fuji C200 are practically unavailable due to high demand and restricted supply, and professional colour films cost around £10 per roll, a financially conscious photographer will naturally look towards using motion picture film as a substitute considering that short ends can be purchased on eBay for under £50 per 30.5 metres, enabling costs of under £3 per roll.
In addition, the quality of Kodak Vision3 film equals and even exceeds that of Ektar and Portra. I've read that when Kodak update their professional colour films, they are essentially applying the latest enhancements from the motion picture product line to them. With this in mind, the benefits of using motion picture film are compelling.
One of the terms one always hears when motion picture film is discussed is ‘remjet’ - a seemingly hard to remove carbon coating that protects the non-emulsion side of the film from scratches, and also serves as the anti-halation layer. In motion picture labs, a special prebath is used that softens and dissolves the remjet layer so it can be buffed off easily.
WARNING: Do not send motion picture films to commercial C-41 labs! If they don't notice and reject your order, the remjet will contaminate the developing solutions and damage other customers' films. If this isn't enough to dissuade you, your photos will come out with a blue-green colour cast. If you aren't developing the film yourself, use a dedicated lab with a special process for ECN-2/Kodak Vision films.
Below I will explain how you can make such a solution, at home, with ingredients that can be purchased cheaply online. The recipe presented here is taken from Kodak’s Process ECN-2 Specifications, page 7-27.
Ingredients and equipment
Table of ingredients
|Borax (sodium tetraborate decahydrate)||20 g|
|Sodium sulphate (anhydrous)||100 g|
|Sodium hydroxide||1 g|
|Water to make||1 litre|
Getting the ingredients
The following advice pretty much only applies to the UK, as that is the limit of my experience buying these items. If you already compound photographic chemicals (as I do), you probably have most of these ingredients, but I did have to buy the sodium sulphate.
Water is the easiest - you may wish to use distilled or filtered water, advisable especially if you live in an area with hard water.
Borax is now banned for consumer sale in the EU, so you will have to buy it on eBay, where it is often sold for slime-making and cleaning purposes. It is quite cheap (under £10 per kilogram).
Sodium sulphate has various uses such as in laundry detergents, glass-making, and textile manufacturing. It can also be found on eBay for under £10 per kilogram.
Sodium hydroxide is also known as lye or caustic soda, and is used as a household drain cleaner. At most discount stores in the UK (and potentially elsewhere), it is possible to purchase bottles of ‘Caustic Soda’ for a couple of pounds. This is sodium hydroxide at over 99% purity, just fine for our purposes.
WARNING: Do not purchase ‘Drain Cleaner with Caustic Soda’ or similar products. They contain other chemicals which may affect the process. I haven’t actually checked this, but as it’s so easy to get the pure chemical I advise simply doing that.
DANGER: Sodium hydroxide is an extremely caustic alkali and will readily dissolve bodily tissues, such as your skin and eyes. The amount used in this preparation is quite small, but it still pays to be aware of the dangers and protect yourself appropriately. Touching the dry powder is relatively harmless, but it reacts exothermically with water. For this reason, always add sodium hydroxide to water and not the other way round.
In addition to the ingredients listed, you will also need various pieces of equipment, including but not limited to:
- Small precision scales/balance
- Disposable plastic cups
- 1 litre mixing jug or beaker, plastic or glass is fine
- Source of heated water with temperature control (whatever you already use as a development water bath)
- Stirring implement (glass rod or an old spoon)
- 1 litre bottle, plastic or glass
First, weigh all the chemicals. Due to the small amounts, you will need to use a precision scale; the cheap ones from eBay are fine. I usually keep them in disposable plastic cups labelled with the chemical they contain. Weighing the chemicals out beforehand means you can put away the scales and clear your work area before mixing.
Next, heat the water to 38 °C, using whatever equipment you use for keeping your development chemicals warm. Pour 800 ml of the water into a plastic or glass jug or beaker. Add the ingredients in the order listed, each time stirring the solution until it is clear before adding the next one.
When all of the dry ingredients have been added, top the solution up to 1 litre and decant it into a sealed glass or plastic bottle. Make sure to clearly label the bottle and keep it away from children etc. as the prebath is caustic. The solution should last at least a month and can remove the remjet from maybe 20 films.
Using the solution
First, pre-soak the film in water at 37.8 °C for 2-3 minutes as normal. Then, add the remjet remover (which should also be at 37.8 °C) to the tank for 30 seconds to one minute and agitate vigorously. Return the solution to the bottle for reuse. Fill the tank with clean water, agitate it and then pour the contents out after 30 seconds. Repeat this until the water comes out colourless and without particulate matter. You can then develop the film for 3 minutes (using ECN-2 or RA-4 developer, C-41 will give a blue-green colour cast especially for tungsten-balanced films) and carry out the rest of the development process as normal.
After fixing, rinse the film, remove it from the tank and unload it from the spool. Now you will have to take it to a sink (or a bath or shower). Run the water over the film and at the same time use your finger on the non-emulsion side to squeegee off the remaining remjet.
Doing this will be much easier if you can get someone to help you. They can hold the film taut under the stream of water, as you move your finger gently over its surface.
Some people online say that you should avoid touching the emulsion side at all costs, but this is pretty much impossible. As long as your hands are clean, it should be fine. Keep the film running under the water for a couple of minutes to remove all of the remjet. It should be pretty easy to see when it has come off.
Finally rinse the film in distilled or filtered water (if available/desired) and then submerge it in wetting agent or stabiliser for 1 minute before hanging up to dry. To help the film to dry faster (beneficial in a potentially dusty room), squeegee it with your clean fingers before hanging it up.
It's a good idea to filter your development solutions before returning them to the bottle after a session. If you don't do this, you will probably get small particles of remjet on your film that will appear as white spots that take ages to edit out digitally. This is especially important if using the same bleach and fixer for both C-41 and motion picture film.
Hopefully this article will help to clear up some confusion or worry surrounding remjet, and show how it can be removed to allow one to process motion picture films at home.
If you don't feel like mixing up the solution yourself, or don't have the space or equipment, a commercial product (probably more advanced than this) that should satisfy your needs is available from photochemical manufacturer Bellini and can be purchased from Nik & Trick in the UK.
If you find any mistakes or anything I have overlooked in this article, or simply have comments, please contact me by emailing ivan @ the address of this website.