HOW TO REPLACE LIGHT SEALS WITHOUT USING FOAM STRIPS, MOVIE CAMERA STYLE

Discussion in 'Classic Manual Cameras' started by peter_de_waal, Feb 19, 2009.

  1. Disintegrating light seals are a fact of life with most cameras manufactured from the 1960's onwards. Here is a method I have used on hundreds of still cameras which is derived from my time repairing cine camera equipment. Arriflex, Mitchell and other film magazines use light seals made from lengths of wool, velvet or felt tape glued in place. This method stands up to the constant loading and unloading of the movie world often for years at a time. In your classic camera they will last forever.
    You will need a few common hand tools, some acetone, Bostic Clear Bond glue, Rubber Cement - I use Ados F2, 8-ply black wool (not acrylic!) and velvet tape. You will also need a well-ventilated space, plenty of time and old camera to practice on. Let's get started:
    1. Cut a piece of paper to cover the film gate and attach it with Sellotape making sure that all edges of the tape are sealed to prevent the ingress of the old foam when cleaning.
     
  2. 2. Whittle down the end of a bamboo satay stick to make a suitable tool to remove the old foam seal material. (Special Tool #1) Unlike a metal scraper, the wood of the satay stick won't damage the paint in the channels or the channels themselves. Note the ashtray is used for acetone during cleaning. I don't smoke and I recommend that you don't either when using a flammable solvent like acetone!
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  3. 3. Scrape the foam gunk off using Special Tool #1. Wipe it off using tissue and keep at it until you have removed as much as you can mechanically.
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  4. 4. Soak a cotton bud very lightly with acetone and run it along the channel. This allows Special Tool #1 to make a near-perfect job of removing the old foam seal material. Be very mindful not to use too much acetone!
    On newer plastic-bodied cameras use methylated spirits for most of the cleaning, only using acetone for the final cleaning of the light seal tracks. Even cameras from the late 1970's onwards use many plastic parts in their wind mechanisms and film counters, as well as plastic exterior trim. Over-liberal use of acetone can ruin them.
    For example, I instructed a friend of mine in this method of light seal replacement, but she used so much acetone that it migrated to the plastic shutter blades of the EOS film camera she was working on and glued them together! It was an early EOS and she, being a student, couldn't afford to have the shutter replaced, so that was the end of that camera...
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  5. 5. Nice and clean, ready for the seals to be put in. Note the door edge seal by the hinge is normally a wide foam seal and this will also have to be cleaned too.
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  6. 6. Here are your replacement seals: 8-ply black wool and velvet tape. These are readily available from your local dressmaking supplies shop. Cheap too. A roll of velvet tape and some 8-ply wool will cost under $10 and you can do hundreds of cameras with this much material!
    Note the old door edge seal at the top right of the picture from the Pentax K1000. Top marks to Pentax for using a strip of felt which sits in a groove next to the hinge area. In this example I reused the felt seal.
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  7. 7. Cut a piece of wool to slightly longer than the length of the channel you need to seal.
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  8. 8. Special tool #2 - a paper clip with the end bent into a curve and polished to remove the burr caused when manufactured. Bostic Clear Bond glue is universally available, usually for under $10.00. Once again a tube is sufficient to seal many, many cameras.
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  9. 9. Use the curved end of the paper clip to lay down a track of glue. Getting the amount right takes practise, but err on the side of caution and you will get good seal adhesion without having to much excess glue to deal with. You may need to practise this on a junk camera till you get your technique perfected.
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  10. 10. Stretch the wool and twist it to close up the weave and make it the same thickness as the seal channel. The amount of twist you put on the wool strand depends on the width of the seal channel you are working with. The narrower the channel, the more twist. Sorry I couldn't get a picture of twisting the wool and laying the seal in, but I only have one pair of hands! The flat back of the paper clip is very useful for setting the seal in place.
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  11. 11. Each time after touching the seal down with the flat back of the paper clip, clean the back of the paper clip in acetone and wipe it off on a tissue. Dip the back of the paper clip in acetone before putting it to the new wool seal each time - this makes it easier to move the wool to the bottom of the seal channel and gives you more time to work. The glue sets quickly...
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  12. 12. Once you are happy with the set of the wool seal along the flat part of the track, apply a drop of glue to the top of the end of the channel and run it along the remaining unsealed channel area.
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  13. 13. Once again twist the wool to match the channel width and pull it into the channel. Cut it off at the appropriate length to reach the end of the channel. Tamp it down with the back of the paper clip as in step 10.
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  14. 14. Once the seal is in place all the way along the channel and you are happy with the way it is sitting, use some acetone on a cotton bud to remove the excess glue from the channel and the back of the camera. As per step 4, don't use too much acetone!
    Repeat all of the above on the top channel. The area where the counter reset latch is located on the top right end of the back requires you to set two seals - a long one from the counter reset latch to the left end of the body, and a short section from the counter reset latch to the right end of the body. It is actually quite easy to install. Just twist the end of the new wool seal strip and insert it next to the counter reset latch, hold the end down with the back of the paper clip, stretch the wool out and pull it down into the seal channel.
    After leaving the camera to sit for ten minutes so the acetone to boils off you can try closing the camera. Only leave it closed for about 30 seconds - just long enough for the seals to take a set from the film door. Then open the film door and using acetone re-set any parts of the wool seal that have lifted and clean any glue from the film door. Also clean any excess glue from the body.
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  15. 15. Some designs have a large wedge of decayed foam in this area near the door latch. Clean it out and use a strip of velvet tape glued into the gap. The picture is of a Minolta Hi-Matic 7SII film door showing the velvet strip attached to the body near the hinge, and another velvet strip folded and glued into the end of the door. I painted the glue on the body and on the velvet strip using a cotton bud, then pushed the velvet strip in with a flat screwdriver blade so it folded as it went in. On the Hi-Matic 7SII the edge of the body is quite deep and acts as a "knife" when it closes, dropping between either side of the velvet strip, sealing perfectly.
    On the Pentax K1000 I re-installed the felt seal that Pentax wisely used to seal the door end.
    If the door edge seal near the hinge is made of foam, then cut a piece of velvet tape to fit the body and glue it onto the body with either Bostic Clear Bond or Rubber Cement. You may need to make the velvet strip narrower with a pair of scissors. It's best to put the door seal strip on the body if at all possible. That way the action of the door closing is just compressing the velvet. Attaching the seal to the door imposes a sliding action on the seal each time the door opens and closes. Still, you only have to re-glue it if it eventually falls off.
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  16. 16. After finishing you can then test close the camera again. If all is well, a final cleaning of any glue smears and let the camera sit open for a couple of hours to off-gas.
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  17. This method is quite time consuming at first, but I can do light seals in an hour for most examples. Some cameras are more difficult as they have kinks in the light channels to allow the film canister to drop out - Nikkormats, Konica Autoreflexes, Minolta's, etc. This might add another ten minutes to the repair time as you have to manoeuvre the wool thread around bends in the light channel and sometimes peal off the leatherette and remove the film back latch mechanism to gain access to the seal area.
    The only camera I have ever had problems with using this sealing method was a Canonet GIII-17QL, where the lower film door seal is a wide strip of foam attached to the door. I overcame this by gluing another velvet strip on top of the first one to make up for the large amount of flexing on this door design.
    This is a repair method that can be considered "permanent." If done properly you will never need to do it again. It is also dirt cheap compared to foam light seal kits. I also find trying to manoeuvre pre-glued foam strips into narrow film channels an exercise in frustration. And to be quite frank, the results using foam strips are never as good. That's why Leitz used the glue and thread light seal method in the Leicaflex.
    Sorry about the pictures on parts 1. & 2. I forgot to resize them to 700 pixels...
    Peter
     
  18. Thanks Peter.
     
  19. Wow Peter, thanks! Even I can figure it out thanks to your clear pictures. If anyone wants to save this they can download a free utility called CutePDF Writer. It takes up very little room on your computer and it will convert any web page to a PDF document, pictures and all. Then ditch Adobe and get the free and much smaller Foxit Reader to view the doc. I did that and now have your excellent tutorial saved for future reference.
     
  20. Excellent step by step instructions, Peter. I've tried yarn, but found that because it does not expand like foam, it did not fill the channels as well as a properly sized foam strip that is compressed to fit in there and expands to fill them up. But the difference is mostly aesthetic, I'm sure yarn works just as well.
     
  21. This appears to be the way my Yashica-Mat was sealed, I don't know if it is original or someone has done a reseal using this method, but it does look like it will last forever.
     
  22. Excellent! This may be the best illustrated explanation I've seen for how to correctly reseal older cameras that predate the use of closed or open cell foam, rather than using the bits of too-thick foam that can cause film doors to bulge from strained hinges and latch areas.
    This really should be submitted as a photo.net article, where it won't be lost since forum discussion threads tend to drift into obscurity. This may serve as a useful reference for others since this topic comes up frequently.
     
  23. I'm glad you all found this useful and thanks for your kind words! I immensely enjoy reading all of your postings on Photo.Net, so it's nice to give something back.
    August, the wool thread does have a degree of "spring" to it, so it is somewhat like foam but without the drawbacks. Gluing the wool in seems to stop loose fibres from drifting about. I've never had a "hair in the gate" from the wool thread on cine cameras using this method, whereas cotton thread seems to break up after a while and you get bits of flock floating around. With the sort of $/hour burn rate on a movie people get really annoyed over this sort of thing.Lex, I have used this method on plenty of modern-ish plastic-bodied Canon EOS's, Nikons and Minolta's too with no problems. However with thier fragile plastic hooks and eyes holding the cases together, electrolytic capacitors leaking corrosive material over the multi-layer, flexible (at least at first) circuit boards, lack of parts and unobtainable ROM update software as a private repairer I don't think anyone will be worrying about the repair of the stuff from that era for much longer...
    How do I go about submitting this as a Photo.Net article?
    Peter
     
  24. Way to go Peter! This is how to write tutorial, complete with excellent illustrations. Great job. I have recently done one using the commercial kit, which was easy to do. But your method is wonderful as well, and also works for those cameras that don't use foam.
     
  25. This is yet another example of the excellence of this forum for classic (and even non-classic) camera enthusiasts. Although I've never had any trouble using the first rate Jon Goodman foam kit and groove strips, and recommend them at every opportunity, this also is clearly an excellent and permanent method of light sealing, beautifully illustrated and explained. I have had one or two cameras that, when opened, have been treated by Peter's method, and I have not bothered to renew them with the foam kit, as they were still perfectly light-tight. It's good to have such an easy alternative in the camera repair toolbox.
     
  26. Excellent!
    Many Thanks Peter!
    Cheers! Jay
     
  27. Thank you, Peter. I'm very grateful.
     
  28. Peter thanks for taking the trouble to share your experience. I'm very impressed with your special tools.
     
  29. Many thanks Peter I've been wondering how to do this more effectively for ages. This way the seals should last as long as the indestructible seals that Praktica always seemed to make, not to mention saving me a whole lot of money as I have a pile of cameras that require this treatment. I'm another one who has downloaded this as a PDF via PDF Download in Firefox. With this article you have given us a great piece of instructive photojournalism!
    Best Wishes and Thanks Again.
    Graham.
     
  30. One vote for Jon's instructions!
     
  31. And a vote for Jon's light seal kits.
    The instructions Peter posted are outstanding, but using Jon's kit will save a lot of time, most of the time. However, in the odd case using Peter's method might work better. For example, I've had no success sealing a Mamiya Press back with foam strips. I will now try wool as Peter suggests, which might just work.
     
  32. Thanks!...that is why the kits I sell include self-adhesive fabric seal material in two thicknesses--1mm and 1.6mm. Plus, of course foam, which is a must for mirror damper use (overlooked in the discussion above) or professional re-sealing of 35mm cameras which were engineered to use foam. One other thing I'll mention (and this might be helpful for your press back): You can laminate the self-adhesive fabric over the foam remarkably well. This will provide the sliding seal needed with the sponginess of a foam seal...something impossible to do with fabric alone. The foam has been carefully designed to have both instant rebound ability as well as ease of compression, almost unlimited life expectancy and a very high ppi (pores per linear inch) measure. This is very difficult to accomplish in the world of foam production. And, since the foam is skived in thicknesses of 1mm, 1.5mm, 2mm, 2.5mm and 3.0mm, you can create virtually any imaginable foam shape or seal type. Example: The Vivitar 35ES (cousin to the Minolta 7sII) and the Olympus 35RC used an odd-shaped foam piece near the latch end which served to hold the film canister in place. It needs to be crafted just so. Please go over to the instruction site and see how I restore these seal pieces in both of these cameras. The 35ES was done over 2 years ago, and that piece is still like it was the day I created it.
    Good luck, and please let me know if you have any questions,
    Jon
     
  33. The great thing here is that we have a good range of methods and materials to cover so many situations and requirements. Jon's kit is so easy to work with. When I started out a few years ago, the advice I found on the 'net was to cut up an old mouse mat, trim the strips, and use those. I did a couple of cameras like that, and it worked, though it required a bit of dexterity with a craft knife and ruler. I found Jon's kit on eBay, and thought I'd try it out. It was so much better than I'd expected, and the crazy thing is, it worked out less than the cost of the mouse mat I'd cut up anyway, not only in money terms, but in terms of the time needed to do the job. The first few 'mouse mat' cameras were Yashica Electro R/Fs. However, the first cameras I used Jon's kit on were my Yashica SLRs, and it immediately made sense to replace the mirror damper foam at the same time as the light seals, because that comes with the kit, and is another advantage over the 'mouse mat kit', and had not been immediately obvious to me until I came to do it. My FX-3's original mirror foam looked fairly intact (unlike the door seals), and had I not had the foam in the kit, I might not have thought to try it, as a mere visual inspection didn't indicate any problem. But as soon as I prodded the old foam with a cocktail stick, it began to fragment. The most tedious part of the whole renewal process is clearing the old stuff away. That done, the rest is plain sailing and quite relaxing work to do. The replacement mirror foam has an adhesive backing, and it you moisten it (as in the instructions), it's easy to work it into position. I make little paper T-shaped templates which I can poke into the mirror box to trim to the right dimensions, then cut the mirror foam to the template and then insert it. I will also have a go at using Peter's method with my Yashica Electro-X, whose seals are shot, and see if I can add a little more to my skill set!
     
  34. Wow! I can't beleive I missed this!
     
  35. Here is a pic of the folded velvet tape I used to seal the door of the Minolta Hi-Matic 7SII in step 15. Apply Bostic Clear Bond to the back of the velvet and fold it with the velvet surface inside. A light coat on both sides of the slot it drops into and then you can just work the velvet in using a flat screwdriver tip in the centre of the fold. If it gets stuck as the glue goes off, just drop a little acetone on the velvet edges with a cotton bud and it will become mobile again.
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  36. Here is another camera I did yesterday. A Yashica Lynx 1000. A very nice camera with an exceptionally smooth and quiet wind mechanism. This must be the quickest seal job yet. It took me 5 minutes to clean the two simple channels and another 15 to apply both top and bottom wool seals and the velvet door seal.
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  37. The Lynx has a door latch mechanism that must be removed to get at the seal area. You can just make out the two bosses that the latch slides on and the cover screws go into. This latch is a piece of chrome-plated mild steel. And I really mean mild! This camera's latch is so soft that it was bent from use and had some dried-up grease on it. I straitened it out, cleaned it and applied Loctite copper-based high temperature lube. It is used in jet engines and stays where you put it at normal temperatures. The latch now slides beautifully.
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  38. Here is the finished camera with the remnant from thinning-down a velvet strip to make the door edge seal. I just glued the edge seal on with Bostic Clear Bond on the back of the velvet and the edge of the body it sits on.
    So there you have it. Choices in the light seal arena. In my experience foam always breaks up eventually, usually after about 2-5 years. Happy shooting with those cool old cameras!
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  39. Ga-loooo???? Wow. Sorry but that is SO risky! And messy. And sticky. And all - fume-ee.
    TEN votes for Jon's. I bought one of Jon's kits off eBay a couple of years ago for a really nice price; just finished resealing and re-mirror-dampening my 9th camera with it - a K1000. STILL have tons of it left!
    Thanks, Jon! Love it!
     
  40. One other thought on this - while the provided stick is a good tool, a generic plastic drinking straw works much better at removing the old gunk from the door channels. Forms very nicely to the shape of the channel, slides effortlessly through the channel, and the old stuff wipes easily and cleanly off the straw, unlike the wood stick.
    A swizzle stick might be an even better option due to its small diameter both for cleaning and reinstalling the new foam strip.
    With the straw, I've never had to use any cleaning solution to remove the "tar". All I do after scraping out the old stuff is dip the wood stick in a little isopropyl alcohol and swipe it back and forth through the channel once or twice to wash off any lingering thin film of residue.
     
  41. The foam seals on my Bronica ETRSi film backs have deteriorated. Koh's camera said I won't get light leaks, as the channels are really deep. I can see that, but thought I'd try it anyway. I found that the thin strips in Jon's kit, the ones for sealing back doors on 35mm SLR's, work perfectly. They're too wide to insert normally, but insert them sideways (adhesive to the right or left), and they work like a charm.
    I would expect that the method described using wool thread would also work well.
     
  42. OOPS! The ETRSi's backs take the the strips the usual way. The inserts take the strips sideways!
     
  43. SLR MIRROR BUMPER REPLACEMENT
    It's also easy to replace an SLR's mirror bumper with the felt seal from the lips of a commercial film cartridge. They have a backing material which binds them together. I can't remember if the Fuji or Kodak ones are better - one has a fold in it and is the better sort to use, as the felt comes off the cartridge cleanly with it's backing intact. I have a plastic film canister full of them after taking about 30 used cartridges to bits.
    If possible, remove the focusing screen from the camera before you start. Many Japanese SLR's of the 1970's onwards have a thin frame holding the plastic fresnel screen in place - you release a catch behind the bayonet mount allowing the frame to drop down with the screen. Check the manual for your camera if you are unsure.
    After removing the old bumper foam with tweezers, clean that part of the mirror box the seal sticks to with a very small amount of acetone on a Cotton Bud or Q-Tip, or whatever they call them where you are. I hold the camera with the throat of the mirror box facing downwards during this cleaning operation to ensure all the old foam particles (or excess acetone!) fall out of the camera. Many cameras use acetate fresnel screens for focusing which can be ruined by ONE DROP of acetone, so be careful and patient and use the acetone VERY sparingly! Not dripping off the cotton bud!!!
    You then pull a used film cartridge apart with pliers, split a strip off the felt seal about 3mm wide and coat the back of the seal strip and the area where the foam was on the mirror box with a small amount of Bostic Clearbond glue. Attach the new felt seal immediately and move it into place. Allow to dry for 10 minutes before you try the shutter once. So long as you are sparing with the amount of glue you should be all done at this point.
    I've done this job many times - it takes about 10 minutes. It's a permanent repair and the mirror action with a felt bump-stop is no noisier than with a foam bumper - most of the dampening action is actually the compression of air under the mirror anyway.
    •••
    I would also like to thank everybody for their feedback about this article. I'm very happy you found it useful. As readers suggested this should be a feature article I twice requested the Photo.Net administrators to make it a feature, but they haven't done so. Money talks?
    Makes you wonder.
     
  44. Thanks for the tips, Peter. Indeed, helped a lot and I managed my Trip without using a glue.
     
  45. I managed to seal an old Olympus 35 RC using this guide. Worked like a charm. Thanks a lot for this information. I even managed to create the odd shaped "film cartridge pusher thingy" using a couple of velvet strips glued together. Although I feel some other material might have been better for this detail.
    Olympus 35 RC light seals
     

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