and costs about $3.56 yd x 66" width. The favorite choice of many builders is the 2.7oz weight. I prefer to buy the 66" width and cut my own tapes and sizes for each particular use. It is much cheaper this way and allows great versatility in its use.The use of "peel ply" and reasons for using it all the time:
What is peel ply?
Peel ply material is a woven dacron (rayon) cloth. It is available from many sources including Aircraft Spruce Welcome to the Aircraft Spruce Web Site!
The peel ply material is generally used to allow the builder to have a "re-bondable" surface which requires no additional preparation once the peel ply is removed. That is very important, however, the peel ply serves other important functions as well. When applied over the wet lay-ups, you have a surface that will allow you to squeegee trapped air out without allowing the glass layers to move and shift around . When the resin/fiberglass layup is cured and the peel ply is removed, the surface will be free of harmful sharp edges and spurs.
The resin surface normally will not totally cure when exposed to air which acts as an inhibitor. The peel ply application will seal the surface and allow the resin to thoroughly cure. This complete curing of the resin surface is very important. Later when sanding or grinding the surface, the "sticky stuff" will not be there to load up your sandpaper with uncured resin.
Note: If you do have the sticky surface because the resin was applied without peel ply, wash the surface with a clean rag soaked with acetone. The acetone will remove the uncured resin and allow load free sanding.
The peel ply keeps all the glass edges down and smooth. When it is removed, there are no sharp points or rough edges left to "grab" you .
The fiberglass construction gets its strength from its ability to flex and not peel. When the lay-ups are cured, sand or grind the edges to a taper thus giving them a leaf spring effect to withstand separation when flexing. A solid edge of several layers will be the first place the separation may occur when put to the test.
Caution! The peel ply does wick up extra resin. You must be careful that, when applying peel ply, you don't pull too much resin from the surface. The peel ply surface may have white areas or stripes which indicates that air had been pulled in. If necessary, add additional resin to assure a totally wet peel ply surface.
Comments or questions? email me @ gsjostrand@sierratel.com
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