Frequently Asked Questions

on do it yourself movie processing

by George Selinsky

V 1.5, October 18, 2003

From the Movie Processing Page

May be distributed freely and modified under the terms of the General Public License.

WARNING: The author/authors of this document make NO WARRANTY as to the information presented here, nor are they liable for any harm/injury/damage/inconvenience caused by its use and/or misuse. This warning may not be removed from this document.

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A spiral reel tankCan I process movie film at home?

Sure it is physically possible to develop (or process, which is the more correct term) motion picture film at home, the question is what sort of trouble are you willing to put up with.

Many still photographers process their own black and white film, and make prints (some of them also do their own color slides and prints). However, it is important to realize that a 36 exposure roll of 35mm film is five feet long, and will snugly fit onto a spiral reel and inside a tank that you can hold in one hand. Some tanks are made that can hold 8 such rolls of film at a time. In a matter of an hour or two, a still photographer can have up to 288 negatives or slides available for printing or scanning.

However, when you realize that same 35mm film is moving through a movie camera at 24 pictures per SECOND, which equals to about 90ft per minute, the amount of film to be processed increases drastically. Those same five feet of film a still photographer processes to get 36 pictures won't even yield a single "shot" or "take" for the cinematographer. That little spiral reel suddenly becomes awfully big.

Super 8 and 16mm black and white film (usually reversal - which doesn't require a print stage), in lengths of 100 feett/30 meters or less is usually the method most suitable to "home processing" efforts, since the film size is relatively manageable for a single person to deal with. 35mm can also be home processed (the US Army a special small rewind style developing tank made for processing combat footage), but loads upwards of 100 feet are not easy to manage and requires a bulky processing setup.

Will it be cheaper than a film laboratory?

This is a difficult question to answer. It largely depends on your equipment's efficiency in using chemistry on one end, and how cheap you want to go. It also depends on your quality standards, and how much you prize your time and labor.

In almost all cases, black and white motion picture film can be developed at a much lower cost at home than sending it to a lab. Movie labs get very small volumes of black and white film to develop, and as such charge the same rates as color film (or even more). Still chemistry can be used for black and white processing, which can be bought off the shelf from any darkroom supplier (with very few exceptions), and mixing your own formulas is relatively simple as compared to color. The economy kicks in particularly with "push" or "pull" processing, which labs charge a premium for due to the need to run a specially controlled batch.

Consider the following formula - you develop 100 ft of 16mm black and white negative film at a cost of $2.00 ($0.02/foot). The process takes about 1/2 hour, plus drying time. A commercial lab charges $16.00 ($0.16/ft) for the same. The filmmaker saves $14.00 for 30 minutes of mildly exerting manual labor - a rate of $28 per hour (not bad for a salary). Then, of course, there is the cost of the processing equipment that has to be accounted for and amortized. Say s/he paid $100 for a spiral reel, it would take 7 rolls of film to pay for itself, which is not bad.

For 35mm film, the case is somewhat different - the increased width of the film eats up more chemistry, and the cost rises to about $0.035 a foot. Labs, however, due to the larger volume of 35mm film they receive for processing, charge almost the same per foot as with 16mm processing (btw, it's important to realize that 35mm film runs through the camera at twice the speed of 16mm, thereby increasing cost per minute of film by two - in addition to the extra width).

Processing color film requires using somewhat more expensive chemistry, which often has a shorter life than black and white chemicals, and requires tighter tolerances during processing. As a result, more attention is necessary to minor details. For movie film, it is difficult to find the proper color chemicals for sale - and sometimes requires modifying still chemistry to suit motion picture processes. Mixing formulas for color processing is more difficult compared to black and white work.

In many cases, commercial labs are much better at controlling variables in color processes than a home run operation, especially when it comes to chemical replenishment. You can easily wind up with bluish or yellowish images without processing control strip tests and making test prints. But calculations show that color processing can still save money over commercial laboratories, so you may decide to indulge if you are willing to do some more homework and maintenance. Specialized processes such as push/pull processing and "skip bleach" can be done at an even greater savings when one considers the cost of customized lab setups and minimums.

What are the advantages?

In addition to the potential economic advantages, there is the advantage of having the film available for review right away (in the case of reversal film). This can be useful for testing the film, and is a boon if you live far from a laboratory.

It also allows you image control that labs charge considerable money for, especially in the case of black and white. You can use a grainier or softer developer, you can alter contrast/gamma to your taste, and even tint your film sepia if you wish.

If you wish to have a rough and shoddy look to your film, you can do this with wild techniques such as hand processing.

Also, many movie laboratories are awful when it comes to developing black and white film, especially reversal film. It is not uncommon to have labs underdevelop film or use very hot solution temperature which causes extensive grain (done to move the film out faster). For them, small format black and white films are considered "amateur dabbling", not serious professional work, and it is treated with less respect than 35mm or Super 16 color negative filmstock, which is the lab's cash cow.

Your film never leaves your hands, which in many cases means your film is less prone to being lost in a large laboratory, damaged by shipping, confused with other footage, or accidentally fogged by a careless lab attendant (assuming, of course, you are more competent than s/he). It is also a guarantee of privacy.

What kind of skills are needed for processing film?

Basically, anyone who's processed still film is usually able to grasp movie processing. It is often advisable to experiment a little with still film processing to get the hang of dealing with film in general, and the habits associated with it.

Processing any film requires neatness, a certain degree of meticulousness, orderliness, and patience. Threading film, and with some equipment, processing it, is done in total darkness (safelights are only permitted for handling certain types of black and white print films that are not sensitive to certain colors), so a fear of the dark would be quite crippling. Threading film in most processing equipment requires the hands to be delicate and sensitive; if you have desensitized, clumsy, or numb hands, you will find the job more difficult.

Remember with movie film, you are dealing with a considerably larger amount of film. As a result, things become a little more complicated and bulky- although the concepts are very similar to still photography negative developing.

A bit of knowledge of photochemistry is sometimes helpful, but not necessary.

To build processing equipment takes some skills in using power tools and hardware, and in many cases requires some ingenuity on the part of the designer.

What kind of money do I need to put into this?

The first expense will be processing equipment, whether you make your own, or buy it. That can vary from buying a pail to do hand processing in, or getting motor and gear parts to make a motorized processor. Processing equipment is very difficult to buy new, and even tougher to find used (in dependable condition). A rewind tank can be had new for about $100, much less used. A Russian made spiral reel processor costs around $100, which handles formats from 8-35mm. A continuous processor can cost from a couple of hundred for an old used model (if you are lucky enough to find one) to hundreds of thousands of bucks for the latest. Drying cabinets can be made for under $50.

The next investment is a thermometer, for monitoring solution temperatures. A reliable processing thermometer with a phosphor coated readout that glows in the dark costs from $25-40, more expensive ones are also available with digital readouts. They should have a tolerance of +/- one half a degree F for black and white, one quarter of a degree F for color work.

A few good glass or plastic bottles are useful for storing chemistry. Glass is better for chemistry as it doesn't breathe and oxidize the chemicals. A simple graduate, and a small liquid measuring cup is useful for mixing solutions, as is a tray or large, highly sterile plastic bucket. A stirring rod is also a good idea.

A kitchen timer is not necessary, but sometimes convenient (instead of glimpsing at a stopwatch).

A hair drier is useful for drying film, as is a fan and air filter (the sort used for air conditioners, to prevent dust from embedding itself into the still wet film). All these items are not very expensive. Photo specific items can be bought in any darkroom photostore, and others can be gotten at stores such as Home Depot and Pergament.

Where can I process the film?

In any place that is relatively free of dust and light, as well as pedestrian traffic. It should be a place you can close off, and have enough room to comfortably work in the dark without tripping over something. Bathrooms are usually not a good idea because of their confined space, basements are usually much better. Make sure dust is at an absolute minimum.

Can I mess up and make a serious mistake?

Absolutely. You can ruin your film entirely with just one flick of a light switch, and many other ways (not only through light fogging). But so can the lab, and yes, this is not as uncommon as we'd like to think. With hundreds of thousands of feet shuttling through the lab each week, regardless of all the preparations and order, something is bound to go wrong somewhere. In some ways, a home processing lab is less likely to go wrong simply because each batch gets individual attention.

Of course, the biggest reason for problems is carelessness and sloppiness, be this at a commercial lab, or a home lab in the back of a minivan. There are instances of chemical failure and equipment breakage, but with common sense they can be avoided, too. Checking everything before you process a batch is a sure way to avoid mishaps. Cleaning your equipment, and keeping tabs on your chemistry is necessary preventive maintainance.

If you take the right precautions, and know exactly step by step what you are doing, you will not be caught by any surprises.

Where do I start?

It is strongly suggested that you familiarize yourself with the basics of processing film for still photography. The principals are exactly the same, i.e. chemical processes, temperature and time issues, drying film. The main differences lie in:

Equipment - spiral reels are closest to the hand tank used to process still film. However, other processing techniques are different depending on the equipment used.

Chemical management - motion picture film eats up chemistry much faster, due to the large size of film being processed at a time. Therefore, issues such as "replenishment" become important.

Difference in processes - while the chemical principals are identical, motion picture processes usually have differences from their respective still processes, particularly an issue with color film. In addition to differences in formula makeup, most color negative motion picture films come with a black rem-jet backing which needs to be removed by a prebath and buffer stage.

What are the processes and their differences?


Black and white negative - simplest of all, requires three baths. The first one is the developer, which develops the image from its latent state. The film's silver is darkened proportionately to the amount of light it received during exposure, thus forming a negative image (darker silver corresponds to brighter areas). The second is a stop rinse, which washes the developer away from the film. The third is a fixer, which removes the excess silver that has not been darkened by the developer. Afterwards the film is washed to remove the fixer, which can otherwise stain and fade the film with time.

The films that use this process are Kodak 7231, 7222, Ilford HP-5, FP-4, and SX200. Processing specs are available with the film data (Kodak and Ilford's sites have them). Black and white negative movie processing differs with still film processing primarily in the choice of developer, the lower contrast D-96 is used instead of the classic D-76. It is possible, however, to experiment with different developers.

Black and white reversal - somewhat more involved. The first bath develops the image as a negative. The second step is the bleach, which eats away the darkened silver, leaving only the undarkened silver behind. The third is a clearing bath, which removes the stain of the bleach. The fourth step is reexposure, which exposes the remaining undarkened silver to light, followed by a second developer. The second developer darkens the remaining silver, forming a positive image (which was chemically reversed during the bleach and redeveloper stage, hence the term "reversal"). The fixer removes any extraneous bits of undeveloped silver, if they remain, then the film is washed to remove the fixer.

Films that use this process are Kodak Plus-X 7276/7265, and Tri-X 7278/7266. You can also develop most negative films as reversal, in this case you must add about 1 and one half stop to the exposure index (i.e. rate Ilford FP-4 at ASA 320, as opposed to 125). Slow films (i.e. Kodak 7231 and Ilford FP5) work best. See the processing specs from Kodak's H-7 publication excerpted on this page.

Color negative - a more critical process than the black and white processes. The color developer develops a color negative image together with a black and white one. The black and white image is then bleached and fixed away, to leave a color negative image behind (which has a special orange color mask, canceled out in printing). A stabilizer is used to stabilize the color dyes and improve drying.

Solution temperature control with color processes is critical, +/- one fifth of a degree fahrenheight is required in the color developer to maintain perfect balance and consistency. This is accomplished by means of a water bath surrounding the processing tank (cold and hot water is added as needed to regulate the temperature) or a chemical recirculation pump is installed, like a Photo Therm device.

Most professional color films for motion picture use are color negative, and accord to the ECN-2 process specifications by Kodak (which requires a special stage in which the film's black carbon backing is removed by loosening it in a prebath and sending it through a "buffer" - some have used cotton with success). Still color negative films use the C-41 specification.

Color reversal - most involved of all processes. The image is first developed as a black and white negative. Then it is "exposed", and a color positive image is developed in a color developer. Then the black and white negative image is bleached and fixed away, leaving a positive color image. A stabilizer is used to stabilize the color dyes and improve drying.

As with color negative, solution temperature control with color reversal is critical, +/- one fifth of a degree fahrenheight is often required in the first developer to maintain perfect balance and consistency, and a similar tolerance is needed for the color developer. This is accomplished by means of a water bath surrounding the processing tank (cold and hot water is added as needed to regulate the temperature) or a chemical recirculation pump is installed, like a Photo Therm device.

All Kodak Ektachrome films use this process. Motion picture Ektachromes use the RVNP/VNF-1 processes, still Ektachromes use the E-6 process. Kodak Kodachrome films use a more involved, specialized color reversal process (called K-14) which works on each film's color layer separately.

Where do I get chemistry?

You can buy most premixed black and white and color chemistry from photo stores that have darkroom supplies. Some are MUCH more expensive than others, so shop around.

Formula chemicals such as Sodium Sulfite and Metol (also called Elon by Kodak) may be carried by these stores, but the best place is the Photographer's Formulary.

What is replenishment and how do I calculate it?

Processing solutions can be either used once and dumped (or used a few times with extended time to compensate for their usage), or they can be rejuvenated by adding a chemical called a replenisher to prevent them from exhausting. The former is not economically viable for motion picture processing, even though it is maintenance free.

Replenisher formulas for each chemical step must be added at a certain rate per foot of film processed. If too much replenisher is added, a solution may become overly active and overdevelop film. The film will be underdeveloped if it is under-replenished. There are charts with each process to suggest how much replenisher formula should be added to each formula. Most of them are calculated for the efficient "continuous line" or "cine processor". The more typical "rack and tank" and "spiral reel" processing device used by home users may demand slightly higher replenishment rates, depending on how oxidized the solution is in the processing tank. This can take some trial and error.

Rewind tanks and reel & trough processors aerate the solutions so much that the solutions cannot be replenished enough - so they are used on a one time basis only.

What are some shortcuts and tricks for developing Black and White film?

For reversal processing, some people use readily available Kodak D-19 as the first and second developer, instead of mixing Kodak's D-94 and D-95 formulas. Others have used Kodak Dektol (including myself). Any high contrast, fast acting developer is a good candidate. Some have also used Agfa Rodinal, which tends to be very grainy but sharp.

For reversal processing, a silver solvent (such as Sodium Thiocyanate) is often added in small quantity to lower grain to the FIRST DEVELOPER ONLY (do not add it to the second developer - fog will develop in the film). Black and white reversal requires fast acting high contrast developers (ones that have more Hydroquinone than Metol/Elon, and use fast accelerators such as Sodium Hydroxide), as opposed to negative film.

For reversal processing, many have trouble getting Sulfuric Acid for the R-9 bleach, and paying for hazard charges for shipment. Car battery acid, available in stores such as Sears, is usually pure Sulfuric Acid in full concentrate. BE CAREFUL WITH SULFURIC ACID - THIS STUFF CAN MAIM YOU SERIOUSLY! Always add acid to water, never the other way around. Wear certified goggles and protective clothes. If you are NOT experienced with this, get help from a qualified chemist.

To speed drying, add a few drops of Kodak Photo-Flow into your final wash, then go over the film with a squeegee right before drying.

IMPORTANT NOTE: Eastman Kodak recently introduced new Plus-X 7265 and Tri-X 7266 films, together with a newly formulated black and white reversal first developer (D-94a) and bleach (R-10).

These two new films can be developed using the old classic Kodak formulas, however when doing this, the new Plus-X 7265 must be rated at 50 asa daylight/ 40 asa tungsten, not the 100 asa daylight/80 asa tungsten rating on the box. The new Plus-X can only be rated at 100 asa daylight/ 80 asa tungsten when using the new Kodak D-94a developer and R-10 bleach. Furthermore, the old Plus-X 7276 can be correctly developed with the new D-94a developer and R-10 bleach only if it is exposed at 100 asa daylight / 80 asa tungsten.

There are no apparent speed changes for the new 7266 or old 7278 Tri-X reversal films, they may be used interchangably in either process at their normal speed indexes - based on Kodak's official information.

The new formulas will be making their appearance on this webpage and the internet as soon as they are released. The new R-10 bleach is said to be more environmentally friendly than the old R-9, it does not use "heavy metals".

Can I develop Color Negative ECN-2 film in still C-41 chemistry?

It can work - there have been reports of successes - but you will get the best results if you substitute the C-41 bleach with the one used by the E-6 still color reversal process, or if you mix the ECN-2 bleach per Kodak's formula (see the H-24 publication online). Remember you must remove the carbon backing of the film before processing by sending it through the ECN-2 prebath (a mixture of Borax and Sodium Carbonate)and then washing away the backing (some report using a cotton swab is successful). Read Martin Baumgarten's post on the matter (which applies to ALL color negative ECN-2 films, of all formats)

You may find it more economical to mix chemicals directly from Kodak's ECN-2 kit, although that requires a VERY large amount of storage space for over 100 liters for each bath. I have not tried to buy ECN-2 chemistry directly from Kodak. It used to be available only through an "account".

Can I develop RVNP/VNF-1 Ektachrome film in still E-6 chemistry?

It can work, but to avoid a magenta color shift, increase the concentration of the color developer by 20%. Read Martin Baumgarten's post on the matter (which applies to ALL VNF-1/RVNP Ektachrome films, of all formats)

The economy however is greatest when using Kodak's VNF-1/RVNP prepackaged chemistry, although it requires massive room to store (100 liters per bath).

Can I develop Black and White movie film in Kodak's T-Max Direct Positive developing outfit?

No - this kit is formulated for T-max films only, it will NOT work properly with regular Kodak B&W films, reversal or negative. It is also expensive.

Can I develop Kodachrome?

No, Kodachrome's process is very involved requiring specialized lab equipment. There IS now a minilab setup for Kodachrome's K-14 process, and premixed chemicals are made by Kodak. But to engineer this from scratch would require quite a lot of experimentation and work.

Some have developed Kodachrome as a black and white negative and also reversal, I have never tried this however. Check Martin's postings for more info.

What is the movie equivalent of 1 35mm 36 exposure roll, for calculating solution capacity from still photochemistry?

Movie film Approximate equivalent in 36 exposure 35mm still film ("135-36")
50 feet Super 8 2.5 rolls
25 feet Double 8/Double Super 8 2.5 rolls
50 feet 16mm 5 rolls
100 feet 16mm 10 rolls
100 feet 35mm 20 rolls

What processing equipment is available?

There are few commercially available processing tanks. One is the Morse/Arkay G-3 rewind processing tank (which can handle all film formats up to 35mm), frequently selling on Ebay for around $40, sometimes even less. Older models of the G-3 have a reexposure window which is very helpful for reversal processing. Others are the LOMO spiral tanks made in Russia (back during the Soviet era), which can be bought used from Russia (incl. the Ukraine) Other equipment was once manufactured by Superior Bulk Film and Kodak. Check Movie Processing Techniques on this page, and also check Martin's post for more info. Also check Ebay for movie processing equipment for sale.

Many choose to build their own, which requires some handy skills but is not impossible. Some have even constructed machine processors and drying cabinets using primarily supplies available from your local Home Depot.

What materials can I use in the construction of processing equipment?

Most metals are not acceptable (save Titanium and Hastelloy C, as well as Stainless Steel Type 316) because they corrode chemistry. Wood absorbs chemicals and re-releases them, causing contamination. Plexiglass and glass is usually optimal. Kodak has a publication that specifies which equipment is suitable for processing equipment design - you can ask them to mail it to you free.

Optimal processing machine design 1) minimizes the oxidation (exposure to air) of chemicals while permitting proper chemical agitation (some have even used nitrogen gas for agitation, called "nitrogen burst"), 2) provides for an effective and even exposure of film to chemistry using a minimal amount of chemicals per foot of film.

May I copy/mirror this FAQ and make additions to it?

Yes, under the General Public License. You must note any modifications/additions from this original and credit your name to them.

For further information, please read the sections on movie processing from the 8mm Metadirectory. Also, read Josh Horenstein's Beyond Basic Photography for easy to understand film processing theory.