Buried Treasure From Ancient 35mm Films

While clearing out a drawer in my teenage bedroom I came across a surprise: a box full of exposed-but-undeveloped 35mm films.  Half B&W, half colour print.  Teenage Alex took a lot of pictures but couldn’t afford to have them printed: long assumed lost these films had languished in the back of a drawer for twenty years.

After twenty summers in a hot bedroom they had not been stored well.  Would any pictures be recoverable?  I’d never developed a film before and it sounded like a challenging project.

An hour with Google revealed:

  • Background radiation causes photographic film to deteriorate over time.  But this gives an even exposure across the negative (a “base fog”) and while it darkens the image it won’t be wholly destroyed.
  • Undeveloped film gets grainier over time.  But film is an analogue medium and this is a slow, cumulative process – with an age of mere decades something should survive.
  • B&W is relatively easy but It’s hard to develop colour print films at home.  C41 chemistry requires precise temperature control at 39°c (so double room temperature) and a water bath would cost more than the project is worth to me.
  • BUT in a pinch you can cross-process C41 colour films in B&W chemicals.  This results in very dark negatives with lots of grain and an orange tint from the film, but if you have a good scanner you can still extract reasonable images from it.


Looked to be worth [1] a try.  I invested in a dark bag, developing tank and a starter kit of Ilford B&W chemicals [2] plus a few more accessories.  Enough to do all fifteen films with a total outlay around £70, or one month of paper rounds.  If only Teenage Alex had known.

Not a professional darkroom.
Not a professional darkroom.


Experiment 1: B&W Films

First I tried processing a couple of the B&W films.  This would determine whether any of them had usable images: better to find out now and admit defeat than spend days doing them all.

There are many tutorials for developing B&W films so I won’t bore you with another.  What I did differently was:

  • Added 20% more time in the developer since very old film needs longer to develop
  • Pre-soaked the film in tapwater for three minutes.  Some people say there are benefits to having the film wet before developer touches it.  I remain unconvinced but it didn’t do any harm.  Care was taken to have this tapwater close to the 20°c of the developer: thermal shock to a film while it’s wet can cause the emulsion to tear, leaving little ‘cracks’ in the final image.


I didn’t yet have a negative scanner so as a quick test I photographed the still-drying film with my phone and inverted the images.  The negatives were good enough to prove it wasn’t a waste of time.

Better than I’ve any right to expect from films left to rot for twenty years!  And these were just snapshots from a naff smartphone camera, really the negatives were in excellent condition.


Experiment 2: Poor Man’s C41

Now for the colour films.  With so many variables I didn’t trust myself to do a full C41 run and opted to treat them as B&W.  It should work: alongside those complicated dye layers C41 film uses silver halide chemistry so something should come out.  Besides these were el-cheapo films and the dyes degrade faster than silver halide, so the best chances of success came from trying to extract B&W images.

A quirk of C41 chemistry is that (assuming chemicals at a uniform strength) film of any speed needs the same time to develop.  100 ASA, 200, 400 – whatever, they all take 210 seconds.  You don’t need to worry about calculating a development time for each type of film which is a godsend when dealing with half a dozen of them from long-defunct manufacturers.  More research showed C41 -> B&W cross-processing is a well-trodden path and that I should treat them the same as Ilford HP5+ 400 ASA film – so a presoak then 6m30s at 20°c plus an extra 20% because of the age of the film.

C41 NegThe films were from diverse manufacturers – “Boots”, “York Photolabs” and a few more esoteric brands.  Some were better than others but all yielded images.  In some cases the presoak water came out a strange colour but it didn’t seem to impact the pictures.  All produced very dark negatives with images only visible when backlit with a bright light.

Here’s an example.  Even held up against sunlight the image is indistinct but it’s definitely there.  Because of the age, my shambolic attempt at cross-processing or both they’re very grainy but the images are still useable.

In conclusion – if you can bear the risk inherent in bodging it yourself, cross-processing ancient colour print film in B&W chemicals is well worth a try.  You’ll only get B&W images but in return you’ll save the fortune it would cost to have professionals try to rescue a film of unknown value.


What Treasure?

Hundreds of pictures of my childhood – family members, long-dead pets, summers and christmases and holidays, even my last day at school.  Once I knew it was worthwhile I bit the bullet and paid for a good scanner.

The Plustek OpticFilm 8100 worked like magic.  With a bright backlight and multiple passes to do HDR it extracted good pictures from every one of the films.  The colour -> B&W tone representation was sometimes odd but the (rather idiosyncratic) software it came bundled with helped clean things up.  For the grainy “colour” negs it wasn’t worth scanning higher than 1800 dpi; the real B&W films yielded much smaller grain and higher resolution pictures.


Notes from a Journeyman Developer

I learned things about home development that I haven’t seen anywhere else.  Some of this approaches control freakery but it’s worked well for me.

  • Read and re-read the instructions for your developer, stop and fixer.  Most errors are not recoverable so you need to get it right first time.  Write down a plan before you start, with timings.  Have a “dry” run with no film and tapwater instead of chemicals so you get a feel for handling the developing tank before you do it for real.
  • If you don’t have a darkroom you’ll be loading the film spiral in a dark bag.  When you zip it up (hopefully with film, spiral, scissors and bottle opener inside) check you closed the two opposing zips correctly.  It’s easy to close the first one then reopen it when you think you’re closing the second.  I nearly ruined a film this way.
  • Don’t contaminate your chemicals.  Use separate jugs for each and wash them scrupulously when you’re done.  Label them, so next time you’ll be using the same jug for developing fluid and it won’t contain trace amounts of stop or fix.
  • B&W chemicals aren’t particularly dangerous but try not to eat them.  Try especially not to get concentrated stop bath on you, the stuff is acidic and I instantly regretted it.
  • Most importantly – control the variables.

    • Developer stage is the most sensitive.  For stop & fix it’s okay to have a small degree of error in the temperature & concentration.
    • Get the temperature of your developing fluid spot on.  All the cheap electronic thermometers I found on eBay read to 0.1°c but when you read the fine print you’ll discover they’re only accurate to 1°.  Not a problem if you’re baking a cake but bad when every degree mis-develops your film by 10%.  In the end I bought an old-fashioned lab thermometer and trained an electric fan heater [3] on the jug until the temperature was bang on 20°c plus 0.1° more to account for loss when it went into the tank.
    • Get the dilution spot on, at least for the developer.  Use a pipette to measure it if you can.
    • If you mixed up a batch of developer for several films don’t expect the temperature to stay the same.  Re-check it before you develop each film and heat again as necessary.
  • If you are developing multiple films in a single run, mix up a big batch of developer all at once.  This will save time and the larger a batch the more accurate your dilution will be.
  • If you can get some, use distilled rather than tapwater for the final wash.  This eliminates the risk of tapwater depositing limescale or other crud on the film as it dries.
  • While Ilford’s instructions say you may use the developer at a lower (1+14) concentration for greater economy everybody I’ve asked warns against it.  Your dilution will be less accurate and the negs allegedly of lower quality.  With Ilfosol 3 costing £9 for 15 films-worth I’ve no reason to push my luck.
  • You can reuse stop and fixer for many films.  10 is a sensible number.  This wasn’t obvious to me at the start and I chucked away a couple of batches before realising.  It goes off after a few days though.




[1] If you suspect a film contains pictures of great value you may do better to pay an expert company to handle it.  They’ll have more accurate equipment and can probably recover colour images.  Their work will be more professional than can be achieved on a living room table.  But where’s the fun in that?
[2] Ilfosol 3 developer, though an expert later told me I might have got better results with Rodinal.
[3] Obligatory disclaimer: I am an idiot; don’t try this yourself.  You might melt the jug and electrocute yourself.  I accept no responsibility for anything ever.


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