Complete, detailed procedures for fiberglass repair are provided
with repair kit, MIL-R-19907C.
Repairing cracks or splits.
(a) Using sandpaper, remove dirt and paint 3-4 in. (8-10 cm) around area of crack.
(b) Rough sand surface to which mat will be added; underside of surface if possible. Surface must be dry.
(c) Bevel edges of crack in a broad V.
(d) Cut a piece of mat and apply to underside of surface with resin mixture. Extend patch beyond break
about 2 in. (5 cm). Press patch firmly into place. Saturate patch with additional layer of resin and then allow 1 to 3
hours to cure.
(e) At the same time, cover top exposed surface with resin, allowing 1 to 3 hours to cure.
(f) For stressed areas, lightly sand first patch and add another patch layer, repeating steps 1.d and 1.e.
(g) Finish sand exposed surface.
(h) Prime and paint.
(a) Remove damaged material. Bevel edges approximately 20° at outside edge of hole.
(b) Remove dirt and paint in area of hole extending away 3-4 in. (8-10 cm), using sandpaper.
(c) Rough sand top and underside of surface to which mats will be added.
(d) Cut two same sized pieces of fiberglass mat that will extend past edge of hole about 2 in. (5 cm).
(e) Coat both top and underside surface and saturate both pieces of mat with the resin mixture.
(f) When tacky, apply one mat to the inner surface and one to the outer surface. Press the two patches
(g) Allow 1 to 3 hours to cure. Additional coats of resin may be added if necessary for appearance purposes.
Sand lightly between coats.
(h) Finish sand exposed surface.
(i) Prime and paint.
When sanding fiberglass, personal protective equipment (respirator,
goggles/shield, gloves, coveralls, etc.) must be used. Failure to do this
may result in injury.
33-9. FIBERGLASS REPAIR (Contd)