| A wide range of epoxy products are produced for both marine and other markets. The products are mainly intended for building and repair applications and in the marine market they are distributed both to professional boat builders and to retail outlets where amateur users can buy the products. Most queries manufacturers receive are from private individuals who are inevitably not experienced in using the products and often have difficulty buying the correct product. These notes have been compiled for the user to both obtain an improved understanding of epoxy products which will complement reading data sheets and also, perhaps more importantly, to address the most common problems the user may experience. This FAQ covers the general question category of laminating and answers questions related to product selection/feasibility and typical problems with using resin as a matrix for fibre reinforcement. "Is polyester resin compatible with cured epoxy?" Polyester resin should not be used over cured epoxy as the cure of polyester will be inhibited if the epoxy is not fully cured and prepared. Also the bond strength will, at best, be poor as polyester is not a good adhesive. "How much resin do I use with fabrics?" This can be approximately derived from the weight of the fabric being used, as follows: Glass - 2 x the weight of the fabric per m2. Carbon - 1.5 x the weight of the fabric per m2. Aramid - 1.5 x the weight of the fabric per m2. In each case this will give roughly 1:1 by volume of resin:fibre. The ideal situation is to have approximately 60% fibre by volume but this can only normally be achieved by professional laminators. "How can I reinforce the wooden surface (hull, deck) of my boat?" This process is known as 'sheathing' and specialist information is available on this site which describes how to do it, what materials to use and how much. "Can I use chopped strand mat (CSM) with epoxy resins?" The simple answer is 'no' - for two reasons. Firstly CSM is used to reinforce the resin in GRP structure, where the resin usually makes up two thirds of the GRP and takes as much of the load as the glass fibre. The reverse is true with epoxy resins. The fibres usually make up two thirds of the volume of the laminate. The primarily role of the epoxy is to hold the fibres in place and transfer the load evenly across the fibres, which bear the majority of the load. The CSM can only effectively be used with an "excess" of resin, because of its structure. The open nature of CSM means that it is very difficult to achieve a high fibre volume fraction. Secondly, the glass surface in CSM is treated to bond well to polyester resin. It can bond to epoxy but it is not so compatible and in some cases a cloudy resin results because of this incompatibility. | 
