Fiberglass type

[ebb]

Tim,
I extensively use Knytex X-mat. I began using it because mat and roving is exclusive to polyester. I'm exclusive to 100% solids epoxy. This is one of those 'unidirectional' fabrics that is stitched together with chopped strand. It is easy to cut and pickup and place in position. Wet or dry. It does not deform like woven cloth.

The X-mat has the unidirectional glass at 45degrees to the run of the cloth. It is docile, fabulous for one shot tabbing (like bulkhead to hull), you can poke this heavy fabric when it is wet into corners with your brush or spreader and it will like to stay there. But you can't mess around with it like cloth because it'll start to pull apart. I do make full size posterbord patterns for nearly everything - and trace it to the X-mat. Some laminators will pull at the X-mat and stretch it to get it to conform to a compound shape. I prefer to cut darts in it like a tailor does to serge.

It's heavy weight stuff, meant to build up laminate in hand lay-up. I can't remember right now but I think five layers of 24oz X-mat is about 1/4". Comes in 19 oz too, which doesn't gobble up the quarts of epoxy quite as bad. When dry it has a rough texture. I would not use a West System epoxy that blushes. X-mat can be used with all three resins.

It is equal in strength to cloth, so I've heard. One guy said he figured one layer of 24oz was equal to 7 of woven. I assumed he meant 10oz. But I have not read comparisons in plain english. Boat-builders use it structurally. It's strong and it wets out well.
I feel that I can sand/grind down into it and not loose integrity if I need to because it is not exactly a cloth.
Single layers of 19 and 24oz will set clear - you can see what its covering like cloth. It's not 6oz stitch-and-glue doodah - it's much thicker and has texture when set. Can always fill the weave with epoxy gel, and/or sand it down.

On surfaces with holes and imperfections, I'll bridge the surface with epoxy gel and place the X-mat right on top DRY and then carefully wet out a smooth no-void surface using a spreader. Magic. AND it doesn't drip or run - seems to hold the resin.

Another action is to wet-out the X-mat on some vinyl film and just peel it off like wet cardboard and place it where you want it. It'll hold its shape if you're careful. Not like cloth. If it won't hug to a compound curve, just take the shears and cut darts in the wet material. I write reminders all over the dry stuff with sharpies - dotted lines for corners etc. Love X-mat!