photo:lightseals

Replacing light seals

Old cameras often had light seals made from a rubber foam which degrades (more accurately disintegrates) over time. The best thing to do is remove and replace them, though this can be a long job depending on the number of seals, their condition and the glue used to attach them.

  • Sharp craft knife or scalpel, e.g. X-acto or Stanley 9mm type.
  • Bamboo skewers.
  • Tweezers.
  • Small paint brush or foam swabs.
  • Cotton buds (Q-tips).
  • Selection of neoprene closed-cell foam sheets, black in colour.
  • Sticky-back felt (e.g. Fablon Velour), black in colour.
  • Isopropyl alcohol, 90% or higher (99% is best, but 95% or 90% are also suitable).

The old foam and glue can be removed using 95% or 99% isopropyl alcohol (rubbing alcohol), a paintbrush and a bamboo skewer.

  1. Cut a square of paper (a Post-It works well) to slightly larger than the cutout where the film mask and shutter are. Secure it around the edge with masking tape to prevent any loose foam from getting into the shutter.
  2. Use the paintbrush to apply alcohol to the old foam. Let it sit for a moment, applying more alcohol if needed.
  3. Begin to rub the old foam off with a bamboo skewer.
  4. Wipe off any residue with a cotton bud (Q-tip) or small foam swab.
  5. Repeat the process until all the foam and as much as possible of the old adhesive have been removed.

For some glues you may need to use acetone – however this should be an absolute last resort, used sparingly and applied with a small foam swab.

  1. Obtain some neoprene foam of the appropriate thickness. This may be sold as “neoprene foam sheet”, “foam rubber sheet” or “neoprene sponge sheet”.
  2. Also obtain some self-adhesive thin felt sheet – this is sometimes sold as Velour (e.g. by Fablon).
  3. Use a metal ruler to mark and measure the foam sheet.
  4. Use the ruler to squash the foam down, then cut the neoprene to size using a sharp craft knife (e.g. Stanley knife).
  • Self-adhesive (sticky-back) materials:
    1. Remove the protective sheet from the back of the glue layer. Handle the felt with metal tweezers to avoid leaving finger grease behind, which will weaken the glue.
    2. Using a paintbrush or felt swab, apply isopropyl alcohol to the glue. This allows you to reposition the felt if needed.
    3. Put the felt piece into place on the camera. Slide it around with the tweezers if needed.
    4. Apply pressure to the felt to secure it in place.
    5. Leave for several hours for the alcohol to evaporate.
  • Neoprene foam used to fill gaps
    1. Use a bamboo skewer or tweezers to push the neoprene into place. Don't squash it!
    2. If the foam is correctly positioned, the metalwork of the camera body will often leave a slight witness mark where the two have touched.

Light seal dimensions

I've made a note of the light seals I used to repair my cameras.

This information is presented here for reference, with no guarantee as to its accuracy.

The C35 Automatic rangefinder requires the following seals:

Location Material Dimensions Notes
Film door, hinge cover Thin self-adhesive Fablon Velour 3 x 25 mm Covers the open section of the film-door hinge.
Film door, hinge filler 2mm-thick neoprene foam 8 x 37 mm Pushed between the door (hinge side) and the black door inner.
Align with the film take-up cavity.
Film door, latch filler 4mm-thick neoprene foam 8 x 45 mm Pushed between the door (latch pin side) and the black door inner.
Align with the black metal tab.
Film door, top edge Thin self-adhesive Fablon Velour 2 x 130 mm Fits along the top edge of the film door.
Film door, bottom edge Thin self-adhesive Fablon Velour 5 x 130 mm Fits along the bottom edge of the film door
Film springs (2 off) 2mm thick neoprene foam 4 x 10 mm Attach to the metal spring which holds the 35mm cartridge in place.
Can be attached with double-sided tape or contact cement.
  • Last modified: 2018/12/06 19:53
  • by philpem