Fabric covering of Caudron's port wing is patched
Keskiviikko 19.2.2020 - Member of Tuesday Club
By the end of January all holes and tears on the Caudron C.59 (CA-50) aircraft’s lower port wing have been mended. The edges of each tear were first sewn together and then a patch for each hole was cut from cotton fabric. The edges of each patch were unravelled in the manner used in the 1920s. The frayed edges help the patch to fasten tightly on the repaired area when the fabric is varnished.
The patches on the upper side of the port wing were glued first. Nitrocellulose varnish was used for the gluing work. This kind of varnish is used also for tightening upholstery fabrics. It is necessary to wear effective protective masks during the varnishing work and there can’t be other ongoing activities in the restoration space of the Finnish Aviation Museum when varnishing is being done.
Before gluing the patches, each damaged area was surrounded with protective tape. The tape limits the work area and stops the gluing lacquer from seeping into the fabric covering outside the patching area. When all patch areas had been taped, a thing sheet of protecting plastic was spread on the wing. The plastic protects the fabric covering outside the work area when all the holes around the wing area are being varnished. A hole was cut in the plastic at each taped area. The edges of the protecting sheet were taped on the tape surrounding each work area. The wing was now well protected for the varnishing work.
Half a dozen Tuesday Club members started gluing the patches on the wing. X-Speed nitrocellulose varnish was used. The first phase was to varnish the patches soaking wet while they rested on a sheet of corrugated cardboard. Then the areas surrounded with tape were varnished. The patches were not immediately moved into their places. It took about five minutes before the lacquer became drier and gluey. After a short while the patches were moved and pressed onto their corresponding repair areas. Another layer of lacquer was applied, and the brush was used to straighten the frayed edges of each patch.
When all the patches had been fastened, the protecting sheet of plastic and the tapes around the work areas were removed. The Tuesday Club team used the gentle blue type of painter’s tape around the work areas, but it was noticed that the tapes have to be removed immediately after the varnishing is ready. If the tape stays on the old fabric for more than an hour, the tape may stick too tightly on the original painted fabric and when the tape is unfastened, it will leave a mark or, in the worst case, the original painted surface will be damaged.
When the 34 patches on the upper surface of the port wing had been glued into place, the same procedures were done on the 32 patches on the lower side of the wing. Now the 66 holes on the lower port wing had been patched.
When the patches had dried, the surfaces were honed smooth and varnished again. The varnishing and honing was repeated four times. Now the patches are ready to be painted, using paint which matches the original paint on the wing. The painting will not be done before the work on the lower starboard wing has reached the same phase.
Photos: Lassi Karivalo.
Translation: Erja Reinikainen.