If you are going to add another coating on top of the lay-up, apply a release fabric over the surface to gain a finely textured, contaminate-free finish.
In areas where you plan to complete secondary bonding or additional coatings, use a release fabric (such as peel ply) over the lay-up. When peeled from the cured or partially cured surface, release fabric leaves a fine texture, free of contaminates and amine blush. After the laminate reaches initial cure and the release fabric is removed, the laminate surface is ready for bonding without further preparation.
Using release fabric eliminates the need for washing and sanding in preparation for secondary bonding or coating. A laminate may be built up in several consecutive lay-ups over period of days. Use release fabric after each day’s lay-up and remove it prior to the next lay-up. When complete, the built up layers of laminate can be post-cured together.
Not all release fabrics have an epoxy compatible coating or a texture suitable for secondary bonding with epoxy. Before building a part, test for the ability to bond to a surface prepared with the intended release fabric at the proposed post-cure temperature.