The surface of the camera around the hole and the patch cut from the old camera are roughened. For roughening, you can use the same rasp or a rotating abrasive disc on a flexible hose. The roughened surfaces are cleaned with a brush and coated with rubber glue. After the first layer of glue has dried, a second layer is applied to it and dried again, according to the site http://forbb.org.ua/
A patch is applied to the prepared place of the camera so that it overlaps the hole by 25 mm and comes into contact only with the roughened surface; roll the patch and proceed with hot vulcanization.
The camera is placed on the slab in such a way that the damaged area with the patch falls into the middle of the folded camera and is under the pressure screw. The slab must be pre-sprinkled with talcum powder. A rubber gasket and a wooden block are installed between the screw and the camera, pressing them tightly against the camera. Vulcanization is carried out for 10-20 minutes (depending on the size of the patch) at a plate heating temperature of 140-150 °. After vulcanization, the edges of the patch are roughened up and the camera is checked in water, for detailed instructions, see here .
The repair of damaged chambers with vulcanization briquettes has some peculiarities. A briquette is a dense paper pulp impregnated with nitrate and enclosed in a round or oval tin box without a lid and with a bottom, to which a rubber patch is glued. The briquette is applied with a patch on the damaged area of the chamber, prepared as described above, and the screw of the clamp is tightened. Then the pulp is loosened and ignited. After it burns out and the box has cooled down, remove the clamp and check the quality of the repair.
When preparing the chamber for vulcanization, make sure that the size of the roughened area is the same as the size of the vulcanization briquette. The center of the patch should line up with the damaged area. Briquettes for repairing cameras can only be used in cases where the camera has a puncture or other minor damage.
Often the place of damage to the chamber is in the immediate vicinity of the valve. In this case, the valve is rearranged to another place, and the remaining hole and damage are repaired as described above. At the valve installation site, a section of 80X50 mm is roughened and coated with glue. On this site, two pieces of side fabric are applied so that their threads intersect at an angle of 30-45 °. Each piece of fabric is rolled up with a roller. Then a patch cut from an old chamber is placed on top and the entire area is vulcanized. The hole for the valve is drilled with a tubular cutter, the diameter of which is 1 mm less than the diameter
