laminates, shown in figure 14-8, or the stepped
method, shown in figure 14-9, view A, may be used.
When the wall is being prepared for the stepped
repair, a cutting tool with a controlled depth will
facilitate the cutout and should be used to avoid
possible damage to the layers underneath. If the layer
of glass cloth underneath is scratched or cut, the
strength of the repair will be lessened. You should
exercise care not to peel back or rupture the adhesion
of the laminate layers beyond the cutout perimeter.
You can accomplish removal of the cutouts by peeling
from the center and working carefully to the desired
perimeter of the cutout. Scrape each step, wipe clean
with cloths moistened with MEK, and allow to dry
thoroughly. Cut the replacement glass fabric pieces to
an exact fit, with the weave directions of the
replacement plies running in the same direction as the
existing plies. Failure to maintain the existing weave
direction will result in a repair that is greatly under
strength. Replace each piece of fabric, being careful
to butt the existing layers of fabric plies together, but
do not overlap them. The laminate layers should be
kept to the proper matching thickness.
When the entire wall has been penetrated, as
shown in figure 14-9, view B, one-half of the
damaged plies should be removed from one side and
the replacement buildup completed; then, repeat
removal and buildup procedure on the opposite side.
If the damage occurs over a relatively large or curved
area, make up a plaster mold that conforms to the
contour and extends 1 inch past the damage, and
insert it in the damaged area when repairing the first
half of the plies. When the stepped method of repair
is used, the dimensions should be maintained as
illustrated.
In areas that have become delaminated, or that
contain voids or bubbles, clean with MEK and
determine the extent of the delamination; and then
drill holes at each end or on the opposite sides of the
void by using a No. 55 drill bit, extending through the
delaminated plies. Figure 14-10 shows the procedure
for repair of delaminated plies.
Additional holes may be needed if air entrapment
occurs when you inject the resin. Use a hypodermic
needle or syringe and slowly inject the appropriate
amount of resin until the void is filled and the resin
Figure 14-10.—Delaminated ply repair.
14-9
