// www.chrisgavin.com: DIY Spiral Proccessing Tank for Cine Film (Updated)

Sunday, July 28, 2013

DIY Spiral Proccessing Tank for Cine Film (Updated)

Followers of my blog will have seen that I've recently been experimenting with home-processing super 8 cine film. So far I've been cutting off short strips and developing these inside a Paterson tank (designed for processing stills films.)

As my tests continued, I felt the need to step up to processing longer lengths of film. Over the last few months, I've been thinking about how to achieve this; to get cleaner results and be able to process lengths of up to 50 feet of film at a time. One can go on to a popular auction site and find old second hand 'Lomo tanks', but these seem to cost around £150 for the 50 foot version ... a lot to pay for a piece of soviet-era bakelite that might well turn out to be incomplete or broken on arrival.

Based on photos I've seen of the old Lomo tanks and using readily-available materials, I set about making a 'Lomalike' tank... After a few false starts and dead ends, here's the current state of the project is in all its DIY glory...

The most complex part of this project was creating a spiral to hold 50 foot lengths of the cine film.

I found that 5mm x 1mm flat aluminium craft wire could be bent into the right shape with the aid of foam strip 'formers'  to temporarily fill the gaps between the wire loops.
The spiral fits neatly inside my chosen processing tank.
The tank is a re-purposed old 35mm film can.

On the underside of the lid, there's a 'low profile' aquarium strainer with an old lens cap glued on to it. This arrangement enables liquids to be poured in without light leaking in too.
A funnel push-fits onto the aquarium strainer in the centre of the lid for adding liquids quickly; a keg tap fitted to the side for draining out the liquids (not so quickly)

I made my first use of the tank last night, processing about 37 feet of B&W negative film using the same Caffenol C-M developer recipe as before. This is the remaining film of the cartridge I'd been developing for my previous tests, so a good length, but not a full roll. There was space for more film though, so if my measurements are correct, the spiral should be able to take a full 50 foot load.
LOADING: Getting the film on to the spiral has to be done in darkness (my loft) and was a little fiddly at first. After about 20 minutes I'd done it; evolving a technique of feeding the film from the cartridge, rotating the spiral gradually and pressing down on the spiral to keep the film in place during the loading process. All I'd read about loading the real Lomo spiral helped; the film is perfs down, and emulsion out, and holding the cartridge at a 45 degree angle seemed to help too. Once the film was on the spiral, I put the spiral in the can and taped up the sides of the can with black tape to keep it light-tight. The rest of the processing took place in my kitchen, under subdued lighting, but not total darkness.

PROCESSING: The tank requires 1 litre of developer to adequately immerse the 8mm film. Pouring in the developer solution was pretty fast, I could get a litre of the stinky brown liquid into the tank in around 15 secs. There's no device for agitating the tank here, so I just gently rocked the tank to move the developer about during the first minute then a little bit more every minute thereafter for the 15 minute developing time.

Drainage of the tank using the keg tap is slow. I found that I needed to gently incline the tank whilst draining, but not too much, because the sides of the film can are definitely not water tight. Drainage took about a minute.

I followed the developing stage with a water stop bath, then standard Hypo fixer. I kept the film on the spiral for washing and drying too.

SUMMARY:  The developing tank works!  There are pictures on the film, but until I can digitize the film it'll be hard to assess the quality of this arrangement. The real test will be to see if the developing is even and whether the spiral has introduced any marks along the film. So at the moment, it's a qualified success. The design could benefit from a faster drainage system and perhaps the spiral could use some kind of top-piece to hold the film down into the grooves (The real Lomo tank has a top plate for this). However, the film did stay in place throughout the developing and only started floating off the spiral during some over-zealous tap jetting during the final wash process. The edges of the can are not watertight, but if the tank is kept level during processing and only gently and gradually tipped during drainage, this doesn't seem to be a problem.

Tonight I've just put a whole 50foot cartridge worth of film into the tank for processing in Caffenol C-M again, (same recipe as before). I've had a NIGHTMARE loading the tank the second time... It all went wrong when I somehow let the end of the super 8 film disappear back inside the cartridge... This meant that I needed to take tools into the dark to try and hack open the cartridge, then I had a roll of film snagging and not dispensing easily... I must have had beginner's luck the first time I loaded the spiral (about 20 mins) because this time I was in the dark for well over an hour. They say you learn by your mistakes, what a lesson! I put this note here in the hope that others might learn this the easy way.  However, once loaded the processing went well.

I made a small modification to the tank this time; a strip of plastic to go on top of the film. This was easy to add, but meant that the film stayed in place on the spiral even during quite vigourous washing and drying of the film. Luckily I'd already made the centre spindle a short M10 sized bolt, so I could use a nut to hold the plastic in place...

The new top bar kept the film in place this time, so I could be a little more vigorous with the washing and drying of the film.

I've added below some stills of the first batch of film to show the results...

I put the film strip on a lightbox and took a few photos. The left side of each image shows the film negative as processed (with a few Levels tweaks), the right hand image shows the image digitally inverted back to positive. These images will look slightly squeezed, due to an anamorphic lens being used during filming.

The first part of the film was some titles and text animation tests.

The new cable car across the Thames

View from the cable car of post-industrial sprawl.

The wonderful 'Egyptian' fa├žade of the old Carlton Cinema in Islington.

 I'm actually quite encouraged by the results, there's certainly a usable image there, I was expecting more blotchy and irregular results than this.

I also took a few stills of individual frames. This is extreme macro photography, the images on the film are only about 5mm wide. For these stills, I stretched the images back to the correct 16x9 aspect ratio to 'undo' the effect of the anamorphic lens adaptor.

COMING NEXT: I'm planning to digitize and check the results of this film, then shoot and process some further rolls of B&W negative. If all goes well, I hope to be trying some colour processing and maybe some 16mm film sometime in the future...

UPDATE 28/12/14

OK, I've now completed a couple of short film projects using this DIY developing technique, so for those wanting to see some results, here they are...

CABLE CAR (2013)


I've now invested in a large film changing bag and have found this a much more comfortable way to load the spiral than locking myself away into my attic space! I processed some 16mm (BW Neg) film today with this tank (again using Caffenol C-M developer) and can confirm the spiral happily takes this wider film too. I think I'm getting about 60 feet on there, not the full 100 foot roll unfortunately...

UPDATE 31/03/15

well I did process some 16mm BW neg film in the same spiral tank too. This is a roll of BW Kodak 'Surveillance' film I shot on Constantine beach in Cornwall. Again I processed this using the Caffenol C-M DIY developer recipe as used on the Super 8 films before. I have no way (yet) of digitizing 16mm movie film, but here are a few stills I shot putting the processed film on a lightbox. (Photoshop levels and inverting back to positive images.)


Anonymous said...


I've been meaning to post since I first read about your experiments using Caffenol, then realized you were using neg film.

Then this DIY spiral came about and I must say, pretty darn impressive! Necessity as they say, is the mother of inventions!

For your further tests, may I suggest using reversal film? Pretty sneaky I guess, but I'm wondering if Caffenol works (no reason why it should not) as a first and second developer, and what bleach would be appropriate. in the reversal process.

Go have more fun! Cheers!

chrisgavin said...

Many thanks Anonymous. I've been using the neg film, because as far as I can see it's the simplest, cheapest processing with the least nasty chemicals. I've read in several places that reversal films (even colour ones) can also be processed as BW negative, but I'm trying not to have too many 'unknown variables' to deal with ; )

I have in mind to try some colour (reversal probably) film one day, and that would probably mean buying a Tetenal E6 kit or similar....

I'd like to get through a few more rolls of this BW neg film first though...

Many thanks for your encouragement!

Friedemann Wachsmuth said...

Awesome work!
I blogged about this in German, hope it is okay I used your photos. If not, just let me know!


Friedemann Wachsmuth said...

Oh, and how did you fix the aluminium wire at the base strips? Glue?

Oh, and on http://www.filmkorn.org/tag/diy/ you can find some more "film hacks" for home processors. Mostly in German, but Google Translate and/or the pictures might still be useful. :)

chrisgavin said...

Friedemann , many thanks for your messages. Please do spread the word! I used waterproof sticky pads to stick the spiral to the plastic base supports. I'll look at your link soon. Thanks again.

Lucy said...

Hi Chris,

Just looking through your blog about processing, I'm wanting to have a go - I used a LOMO tank a few year go and would like to try again. Do you know anywhere in London that I might be able to hire or borrow one?

Many thanks

chrisgavin said...

Hello Lucy,
I've never used a real Lomo tank, just my own homemade one. I believe that Nowhere Labs http://www.no-w-here.org.uk in east London is a place where you can go to process your own films. This seems to be a kind of film Co-op that you pay to join; though I think they do classes etc. too. It's probably worth giving them a call.
DIY processing is a great thing and you really feel like you own every frame once it's done. Good luck.

nick said...

Well done, impressive, however I don't think I would have the patience or skill for 20 minutes of loading this reel.
It is tricky enough on a lomo reel.

harry said...

Hi Chris,
I just got inpired by your nice idea and will build a version of your tank. I would be intrested if you had problems with the chemistry and the aluminium wire? Very alkalic developers would react with the Aluminium to Hydrogen. I think it will work without problems for like rodinal and any fixer - but did you test reversal chemistry so far? It contains a sour potassium permanganate solution. Not to speak of the things in E6 chemistry. Maybe you should add a hint about the spiral material for different processes. I will tell you how my experiments turned out.
Best regards,

chrisgavin said...

Hi Harry,

Many thanks for your comment, I'm glad you've raised this!
I had some people on the filmshooting forum raise this warning too. Because I only used the tank for BW negative developing, I never had any problem with such chemical reactions.
I don't think I would want to try this with reversal processing, and just don't really fancy handling those kind of chemicals anyway.
I did also purchase some steel 'strapping' material and a larger plastic film can. I never got around to it, but I was thinking about making a 2.0 version with these more suitable materials.
Good luck with your tests, but stay safe too.

Sam Margulis said...

For those looking for reversal bleach ideas, you can use a mixture of hydrogen peroxide and white vinegar at 105°F. (30mL of vinegar per 250mL peroxide for 6 minutes).