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 Aeropoxy FAQ    Why Use a Peel Ply? 

Why Use a Peel Ply?  Does a Peel Ply Starve a Laminate?

The use of a peel ply, or tear ply, offers several benefits when constructing a laminate with epoxy resins.  It’s a fabric that is applied over the last layer of cloth before the laminate is allowed to begin its cure.  Since it does not bond to the laminate, it will peel off when and if, additional laminating or bonding is ready to continue.  It’s often used when the lamination process has to be halted before all the plies of cloth have been applied.  It leaves a roughened surface that does not require further preparation before laminating or bonding continues, i.e. sanding/scuffing the laminate.

The reasons to use a peel ply far out-way any objections not to.  First, as mentioned, there is virtually no preparation necessary before continuing laminating or bonding (with the exception of areas where the peel ply wrinkles and you’ll have resin rich ridges that are easily sanded or ground off).  Second and very important, peel ply protects your laminated parts from dirt, dust and contaminates that they may be exposed to over many days, months or even years before they’re needed.  Third and maybe the most beneficial, it leaves a much smoother finish on the laminate than you would otherwise have. It minimizes pinholes and virtually eliminates the weave of the cloth, which eventually has to be filled in during the “finishing” process. 

A number of types of peel ply materials are commercially available.  These include, Teflon coated fiberglass fabric, fiberglass fabric coated with other release agents, as well as coated and uncoated nylon fabrics.  Some AEROPOXY users have had good results with very tight weave Dacron fabric purchased from sewing centers and retail fabric shops. 

It is highly unlikely that the use of peel ply will starve a laminate.  The technique of applying a peel ply involves laying it on the back of a wet laminate and pressing it into intimate contact.  The goal is to lay it on as smooth and wrinkle free as possible, while avoiding trapping air pockets under it.  Peel ply fabrics are tightly woven, which minimizes the penetration and collection of resin, so the amount of resin removed with the peel ply is minimal when it is torn away.  The tendency for amateur builders is to use more resin than necessary, resulting in a resin-rich laminate.  The use of peel ply will help to control this common fault.