Alternative to foam

Discussion in 'Classic Manual Cameras' started by john_robison|4, Dec 29, 2017.

  1. I need to replace light seal foam but the groove is so small I cannot correctly position pregummed foam. I have seen black yarn used in some German cameras but don’t know how it is affixed to the metal. I’m thinking perhaps contact cement but appeal to the collective wisdom of CMC users.
     
    Last edited: Dec 29, 2017
  2. paul ron

    paul ron NYC

    you can get plain foam and do it the old fashion way with contact cement at the bottom of the groove.

    when i have tight fits, i wet the adhesive a bit so it slides right down. the next day, just go over it with a dental tool to sure up the stick.
     
  3. m42dave

    m42dave Dave E.

    John, I have mostly used black cotton crochet yarn as a replacement for foam in the door seal, with a dab of Pliobond at each end.

    You can also do the same with strips of closed-cell foam or Neoprene. It will hold in place with wall pressure, and maybe a little cement at each end. I no longer use adhesive-backed foam (except for the door hinge) as it is more difficult to work with.
     
  4. Thanks m42, The crochet yarn idea sounds viable.
     
  5. I use ordinary black knitting wool, kept in place with silicone adhesive. I've done many cameras like this. There's no need to scrape out the old foam, If the groove is very narrow I unravel the wool and use one of the three strands.
     
  6. If you're talking about the channels along the length of the film door, I'd clean out the old crud and call it quits. Those seals were there to keep out dust and moisture. The condition of seal at the film door hinge is critical. It's the main source of light leaks in SLRs. Filling up the door channels with yarn, foam or whatever often makes the door hard to close and can screw up the release latch or distort the door. The interference fit between film door and body is sufficient to block light with or without bits of foam or yarn. Many late model SLRs had foam only at the door hinge.I've stripped out dry or sticky foam from many older Nikons with no issues.
     
  7. Looking carefully at the camera, a Olympus Pen FV, I got to wondering if this could be the case. The channels in the body are very narrow and the folded metal lip on the door is a close fit. Think for now I'll just place a foam strip on the door hinge and at the closure side. We should have some sun the next few days and I'll load up some ISO 400 B&W, take the camera out and make sure all surfaces are exposed to sunlight. I'll run off a 10 or 20 exposures, and develop the film to see how it looks.
     
  8. there were lots of eBay vendors selling pre-cut foam with adhesive on them. So cheap that aside from delivery time, there's no reason to roll your own.
     
    Gus Lazzari likes this.
  9. Thin adhesive-backed foam is about a buck for an 8x10 sheet.
     
  10. But you see, in the very narrow channel of the Pen FV the gummed backing WAS the problem. No matter how carefully or slowly I introduced the foam strip to the groove the gummed back would 'grab' the side of the channel and twist the 1mm square piece sideways. I had very bright light, +6 reading glassed, and a narrow bamboo stick to press the foam into place. The groove in the body of the Pen FV is very narrow, and tapered slightly toward the bottom.

    At any rate, we have some rare sunlight in the pacific northwest yesterday and today. I've loaded some ISO 400 B&W and yesterday took the camera outside and made sure all surfaces had as much sunlight as I could. The camera has sat all night in bright desk light and today I'll go out and shoot some more.

    The only area I've foamed is the back hinge. The rest is bare. So this will be a test to see what we shall see.

    By the way, Aki-Asahi has been very helpful and has offered either a refund or to send another kit free. He is eager for a good customer experience and very understanding, offering any help he can.
     
  11. m42dave

    m42dave Dave E.

    That's the reason I no longer use adhesive-backed foam. Moistening the backing first can help, but adhesive really isn't needed, except at the ends. I've replaced seals in at least 3 dozen cameras and they have always stayed in place that way.
     
  12. Are you sure it needs any light seal? Many older cameras had a labyrinth design around the doors, etc. that blocked out all light, my roll film Kodaks and 35mm Retinas and Leica M are like that although the Leica needs a seal around the small inset door.
    .
     
  13. That is what I'm going to find out today or tomorrow. I only foamed the hinge area and loaded ISO 400 B&W. Will see what happens. We have some rare sun today.
     
  14. NO FOGGING on test exposures. This is with foam only at door hinge. I loaded a 36 exposure roll (72 exposures with half frame) and ran off 20 exposures (with leader 20 inches). Ran 2 more blanks, went in the darkroom, opened the back, snipped of the film and loaded it onto the reel. I'll cut a leader and reload the rest of the roll. HC-110, 1:60 as a one shot 70F, 10 min, agitate every 3 min. water stop, fix, rinse, photo flo, hang up to dry...and absolutely no sign of fogging or light leaks. Camera exposed to full (winter) sun and left on desk overnight with very bright LED lamps at about 18 inches.

    I think C Watson has it right, well at least with the Pen FV it appears the door channels are light tight as they are, without foam.
     
  15. I used to have pre-cut door seal strips from John Goodman, but eventually used them all up. As others have said, ebay can usually find you a kit for common cameras seals, but I have found A4 sheets of foam from a hobby shop, cut using a decent steel rule and a very sharp hobby knife to be fairly straightforward. I don’t bother with adhesive, if the seals are cut slightly wider than the slots they stay put, and I’ve not had any come out. You can usually find foam from packing of electrical items etc. that suits other seal applications, and double sided sticky tape to fix them in place, again, cut to size with a hobby knife. A trick from John Goodman’s excellently titled ‘A light seal Odyssey’ booklet is to use a bit of blu-tac (at least that’s what we call it in the UK- stuff you stick posters and other paper items to a wall temporarily) and jam it in the door hinge before closing the door (very slowly) gives you the appropriate and minimum thickness of the door seal. Don’t forget to stick a bit of card across the shutter aperture. Nothing looks worse than an index finger through a shutter.
     
    Last edited: Jan 2, 2018
  16. A kit that I bought came with some purell hand sanitizer that you applied to the adhesive or groove first. This lets you position the foam. Once the hand sanitizer evaporated, the adhesive would stick.
     
    Gus Lazzari likes this.
  17. Sounds like a good idea. So far, just replacing the foam on the hinge side seems to have done the trick. I'll probably have to wait for the high summer sun at my 47N location to be sure no more foam is needed. But that sounds like a good trick for future projects when faced with narrow body channels. Thanks for the information.
     

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