Cleaning Remjet/tar residue from UPB1A dev tank reels

Discussion in 'Color: Film, Paper, and Chemistry' started by philpem, Aug 12, 2018.

  1. philpem

    philpem Subscriber

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    I've just picked up a Lomo UPB-1A dev tank in fairly good condition -- some superglued cracks which haven't held, but it looks repairable.

    Problem is one of the reels is absolutely covered in what looks like Remjet or tar from chemical processing -- it's a black coating all over the reel.

    What's the easiest way to remove this mess from the reels? Solvent and scrub with a nailbrush or toothbrush, I guess, but what solvent would be appropriate?

    Thanks
    Phil
     
  2. lantau

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    It could be remjet residue or black residue left from colour developer. For both I use acid in combination with a brush. You'll definitely need mechanical force. Since I have sulfuric acid at hand I use that. The dilution is something you want to work out. Just don't use very highly concentrated acid. More in the range of 3-10% max.

    And you should have at least some clue about acids if you want to do that, obviously. I do it indoors, but if you are unsure do it outside. Eye protection is necessary as well as old clothing. Using a brush (or an old sponge cloth) will lead to droplets going your way sooner or later.

    Strong alkali might do it as well. But I consider alkalis to be more dangerous for the average user. Acid washes off the skin much quicker. If you were to get 100% sulfuric acid on your skin you just need to stay calm, proceed to the nearby watertap (don't run) and wash it off. No harm done. But do stay close to a source of water for washing off at all times.

    Oh and normal remjet removal solution (mild base at pH 10) will not work. Once treated with it, remjet becomes nasty sticky stuff. And that stuff will not be loosened again by that solution.
     
  3. mshchem

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    From looking at this o Ebay, looks like the reel is general purpose polystyrene. No solvents or strong acids! I would clean best you could with a brush, dish soap and warm water. I have a 1940s vintage Bakelite tank (black thermoset used for tank) my Dad used epoxy glue on it, still intact.
     
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    philpem

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    Eep! I'm glad I tried a cloth and isopropyl alcohol (rubbing alcohol) as my first go...!

    As it turned out, most of the dirt was on the bottom of the reel, not in the grooves. A good hour spent rubbing the bottom of the reel with a cloth soaked in isopropyl took most of the dirt off (looked like carbon dust, so I'm guessing Remjet). A clean cloth run through the film track got rid of the last of it. It's now almost pristine :smile:

    Thanks for the suggestion of using epoxy for the repair - I was leaning that way as the superglue the previous owner used hasn't held. Hopefully Araldite will work fairly well, though I'm torn between that and J-B Weld. I might mix some carbon or black plastic into the Araldite as filler to try and cut down the risk of light leaks or shrinkage of the epoxy... though I'll have to do my "is this a good idea?" bookwork first!

    Looks like I'll have to do a bit of sanding afterwards, the two pieces which broke off don't quite fit in the gap; the one on the right is sitting at a slight slant. The top lid looks like an easy fix though, thankfully!
     
  5. lantau

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    Keep in mind that most solid polymere objects like your spiral will not just melt away because you get some acid onto it. According a stability table I've got, polystyrene is actually very stable in hydrochloric acid and sulfuric acid up to 20%, at 20°C. At 50°C in sulfuric acid it is only stable, not very stable.

    The short exposure for cleaning should be uncritical. I'd be more careful with any styrofoam, though.
     
  6. mshchem

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    You can blend black plastic or carbon I wouldn't go over 20% loading. Plastics are routinely "filled" with minerals, fiberglass etc. The epoxy shouldn't have a lot of shrink
     
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    philpem

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    Fixed the tank the other day - Araldite worked great, but I ended up using two tubes of Z7 superglue debonder to remove the old glue.

    Everything's stuck together with Araldite now, and the pieces lined up almost perfectly (had to sand off some ridges and gaps along the top edge of the tank). No leaks! :D

    So I guess the next step will be to get my hands on some Super 8 film and develop it...
     
  8. darkroommike

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    Cleaning tar off developing racks, back in the day, Hope recommended Lysol Toilet Bowl Cleaner, the racks had stainless steel sidewalls but lots and lots and lots of rollers and nylon bearings, squirt the stuff on and the tar would just run off/ Not sure what it would do to styrene, but if all else fails you could try a drop of two. You wan the acid toilet bowl cleaner not the stuff with bleach and NEVER mix acid cleaners with bleach!
     
  9. pentaxuser

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    Is this normal remjet solution to which you refer, stuff you buy or is this stuff that is made at home from ingredients that do not work? It sounds as if it changes the state of remjet from a solid substance to a stick substance which cannot be scraped off while sticky. What happens to the sticky remjet afterwards? Does it re-set and then not even become sticky again if you try and use the removal solution for a second time?

    Any help in clarifying my confusion is appreciated. Thanks

    pentaxuser
     
  10. fdonadio

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    It’s the pre-bath specified in Kodak’s documentation:


    Prebath 2 (PB-2)
    Water 27 to 38°C (80 to 100°F) ....... 800 mL
    Borax (Decahydrated) ................ 20.0 g
    Sodium Sulfate (Anhydrous) ................. 100 g
    Sodium Hydroxide ............... 1.0 g
    Water to make ............................ 1L
     
  11. pentaxuser

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    So is this the normal remjet removal solution to which you believe lantau was referring which allegedly doesn't work with the consequences that lantau describes? Is that your experience of it as well? Anyone else here use this with similar lack of success?

    Thanks

    pentaxuser
     
  12. fdonadio

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    Yes, I believe so, as “normal” would, at least for me, mean “what one would normally use”. And that’s the formula as specified by Kodak in their documentation about te ECN-2 process.

    I never had any problems with residue, but have to say RemJet will stick to tanks, spools and everything else if not washed off properly.
     
  13. pentaxuser

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    Thanks. So it works perfectly well but the user needs to wash it off completely after applying the solution. It is a pity that the lantau post seems to suggest that the solution per se is ineffective

    pentaxuser
     
  14. fdonadio

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    It works perfectly well to get RemJet off the film. It is very important to fill the tank with water and dump it several times to get the RemJet off of everything inside it (the best you can) and, after the processing, thoroughly clean the spool and tank, as to prevent the RemJet from sticking to them after drying.

    From my understanding, @lantau says the pre-bath solution will not work for RemJet that dried and stuck to the tanks and/or reels and, in that particular case, something stronger is needed.
     
  15. lantau

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    I'm using the other Prebath described by Kodak. I don't have any Borax at the moment and, given the amounts needed per Litre, it is an expensive way to make that prebath. I use the carbonate/bicarbonate version. Those two chemicals are available at drugstores at a very low price. Made with deionised water the pH is spot on 10.0.

    There seems to be a misunderstanding here. I was replying to the OP, who had remjet stains on his tank. At that stage the prebath from the ECN2 process will not be effective. Remjet residues are not the same as virgin remjet. What it can do is to chemically modify the remjet layer on film, such that it can be wiped off. With a cloth or a water jet/water knife. In an ECN2 machine that is a rapid process. 10s in the prebath and then it will run through the water knife. At least that is what the Kodak documentation says. I can say that the jet from a simple shower head will not remove the treated layer from Kodak film. I heard anecdotes that Fujis version was much easier to remove. But that's not really applicable any longer.

    In my tests the remjet layer on film was modified by the alternative prebath (PB-C1) and became removable almost instantaneously. I simply took a short strip of film and pulled it through the solution. Tests done in full light.

    After that initial bath the remjet material seems to become permanently changed. While the loosening is instant there is probably a time window before it becomes too nasty. My guess is that it is quite ok while dissolved in water and while in that mentioned time window. I don't use the method of remjet removal inside the developing tank. It's a lottery whether something will stick to the emulsion or not. And the question is how it will manifest in the final image. A thin redish layer, or additional grain, or anything in between?

    I wouldn't shake a dev tank with that prebath in it, btw. If you must use that method then fill, wait 5s and drain with minimal movement. Then use plain water to continue as described on the interwebs. There is a german blogger (don't have the link any longer, need to try and find it again somehow), who pointed that out after experimenting himself. I think the continuing exposure to the base will increase the chance of smearing and transferring the dissolved remjet onto any surface. It might be shrinking that time window.

    I did experiments were I moved ECN2 film through a tub full of prebath in a seesaw fashion (think developing giant prints by moving the print through a trough like developing dish) to loosen the remjet layer. Then hanging the film from a line and wiping it down. It turned out not to be the way to go. I still have remjet in that tub and also a bucket after more than a year (or is it two by now). I guess I should properly clean them as described by me above. It is mostly small black spots. And they actually come off sporadically and settle on my color chem glass bottles which I put into the tub to get them up to temperature. It is messy stuff.

    Well, the success varies. Personally I don't want to risk contaminating the emulsion and I will not expose my tank to remjet ever again. I believe I described in another ECN2 thread how I treat film in the dark without getting the emulsion side wet.
     
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