Applying Woven
Cloth and Tape
Fibreglass cloth is applied to surfaces to provide reinforcement and/or abrasion resistance, or in the case of some timbers, to prevent grain checking. It is usually applied after fairing and shaping are completed, and before the final coating operation. It is also applied in multiple layers and in combination with other materials to build composite parts.
Fibreglass cloth may be applied to surfaces by either of two methods. The “dry” method refers to applying the cloth over a dry surface. The “wet” method refers to applying the cloth to an epoxy-coated surface often after the wet-out coat becomes tacky, which helps it cling to vertical or overhead surfaces. Since this method makes it more difficult to position the cloth, the dry method is the preferred method, especially with thinner cloth.
Dry Method
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- Place a metal straightedge on top of and midway between the two overlapped edges.
- Cut through both layers of cloth with a sharp utility knife, being very careful not to cut too deeply.
- Remove the topmost trimming and then lift the opposite cut edge to remove the overlapped trimming.
- Re-wet the underside of the raised edge with epoxy and smooth into place. The result should be a near perfect butt joint, eliminating double cloth thickness. A lapped joint is stronger than a butt joint, so if appearance is not important, you may want to leave the overlap and fair in the unevenness after coating.
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Wet Method
An alternative is to apply the fabric or tape to a surface coated with wet epoxy. As mentioned, this is not the preferred method, especially with large pieces of cloth, because of the difficulty removing wrinkles or adjusting the position of the cloth as it is being wet out. However, you may come across situations, such as applying fabric on vertical or overhead surfaces, when this method may be useful or necessary.
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Remove the excess epoxy with a plastic spreader, using long overlapping strokes. The cloth should appear consistently transparent with a smooth cloth texture.
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Follow steps 7, 8 and 9 under the dry method to finish the procedure.
Any remaining irregularities or transitions between cloth and substrate can be faired by using an epoxy / filler fairing compound if the surface is to be painted. Any additional fairing done after the final coating should receive several additional coats over the faired area.