Hairline cracks on the hood

[CRZN427]

I'll start off by admitting that I am no expert.

There are at least two ways to "stress the fiberglass".

One:

Attach a piece of fiberglass to something, and then bend that something so that the fiberglass is being forced into a different shape.

This can be from the weight of the body pushing down on the frame attachment points or from the hood and trunk area where the popular struts are used to lift and hold the hood and/or trunk open.

Even when the hood and/or trunk is closed the strut is applying force to the brackets and eventually, on most installations, to the fiberglass. This is introducing stress into the fiberglass.

Another way:

Build up the fiberglass in layers, sound familar, and have some differences in the resin mixture, the cure temperature, the thickness of the build up or possibly items that are embedded in the fibergalss such as hood, trunk and door mount nuts or bolts.

If the outer layers of fiberglass are cured at a different rate, or with a different resin minture, than the inner layers, there will be stress within the fiberglass generated by the two bonded surfaces trying to settle in their own shape.

The net effect is similar to the bi-metalic strips that are used in thermometers, where a change in temperature causes one of the strips to change length at a different rate than the other srtip and the bi-metalic unit curls to drive the gage pointer.

If you prevent the bi-metalic strip from bending, the two layers will be under some stress and it will likely show up as small wrinkles in the surface and/or cracks on the surface of one of the materials, probably the one being stretched.

This kind of stress is internal and will not be significanlty effected by how the body is mounted. Applying resin over the area, by sanding out the cracks and adding more material, may cure the problem and it may just start the process over again when the fresh resin cures on the existing panel.

There must be a fiberglass expert out there who has had experience in this area and can provide some useful advice.