Hi, all--
This is a burning, itching question in my skin...er, mind.<G>
I have gotten a whole bunch of this sorta cool 'glass fabric bestowed upon me, but I don't really know much about it. It is a woven roving with matting stitched to the back...OK, it's stitch-mat...but what is sort of odd about this stuff is that unless you look closely you do not see the crossweave and it looks for all the world like a unidirectional lay of strands on a mat backing. I wonder if anyone can shed some light on this one, as to what the material actually is/is called, and where the best--or, more my question--and worst applications come up.
I also came up with some healthy-size offcut pieces of 2 inch divinicell. I've looked all over the net and cannot find any real specs for the stuff with any of the searches I have done. Mainly, I wondered as to the "R" value of the stuff...I'm thinking of my new icebox here. Two layers of that stuff, 'glassed over inside and out with formica and trim on top, sounds like a pretty fast and easy icebox, but I wonder if anyone has experience with working with this material, and how much i should 'glass over it to make it as tough as the 1/4", 'glassed-over plywood that would otherwise make up the inside and outside around the high-value Dow foamboard I was going to use.
Any input appreciated.
Best,
Dave
Just Itchin' To Ask
-
Tim
- Shipwright Extraordinaire
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Roving with mat attached is not an uncommon product. Since all laminates using woven roving require a layer of mat between each layer of roving (the weave of the woven roving is so large and so open that layers of it laminated directly together tend to leave large voids and even open spaces, especially when laminating over previously-cured sections; the mat helps bind the layers together and eliminates this problem), manufacturers began stitching the mat directly to the woven roving, which surely reduced labor costs during boat construction. Instead of the labor required to install both layer of roving and the layer of mat in two separate pieces, the combo product allows both to go down at once.
This process makes a heavy, thick material that builds up fast and creates the typical resin-rich type of laminate we're used to in older boats. It should be used for large-area laminations (such as laminating hulls and decks), and would likely be difficult to use for smaller pieces and fabrications calling for sharp corners and changes in direction. It would also work for certain structural reinforcements if the underlying "form" was designed with smooth radii and no sharp angle transitions.
I would generally say its uses are somewhat limited in boat repair (only because most of the time a material better suited to the task is readily available), but it would be good for adding thickness to existing laminates, or for building up top skin over a new core section, or reinforcing the keel area, or some such--anywhere a basic, thick, heavy laminate is desired. It should be avoided in small areas, or for small sections of tabbing, mostly because rolling it out successfully can be tough. That said, since you have it, if it works somewhere--use it. There are materials now available, as you know, that create strong laminates with less weight and a higher fiber-resin ratio.
Using this mat/roving stuff would be overkill and probably difficult for an icebox, with all the corners and such. I used some 24 oz. roving on the bottom of my new icebox, though, to provide a tough base for all the heavy blocks of ice that would be thrown down there. But on the sides, I used a few layers of ligher cloth that were easy to install and roll out.
R value of Divinicell...no clue. Since it's not designed as an insulating foam, it may not even have ever been tested for those specs. Dunno. I used 4" of Homosote (polyisocyanurate), which has a high R value. Cheap at Home Depot.
If you have any need for flat panels of fiberglass that you could then cut up and use for myriad other purposes, this mat/roving combo material, laminated to whatever thickness on a flat piece of Melamine or some other surface that would allow release, would be perfect.
This process makes a heavy, thick material that builds up fast and creates the typical resin-rich type of laminate we're used to in older boats. It should be used for large-area laminations (such as laminating hulls and decks), and would likely be difficult to use for smaller pieces and fabrications calling for sharp corners and changes in direction. It would also work for certain structural reinforcements if the underlying "form" was designed with smooth radii and no sharp angle transitions.
I would generally say its uses are somewhat limited in boat repair (only because most of the time a material better suited to the task is readily available), but it would be good for adding thickness to existing laminates, or for building up top skin over a new core section, or reinforcing the keel area, or some such--anywhere a basic, thick, heavy laminate is desired. It should be avoided in small areas, or for small sections of tabbing, mostly because rolling it out successfully can be tough. That said, since you have it, if it works somewhere--use it. There are materials now available, as you know, that create strong laminates with less weight and a higher fiber-resin ratio.
Using this mat/roving stuff would be overkill and probably difficult for an icebox, with all the corners and such. I used some 24 oz. roving on the bottom of my new icebox, though, to provide a tough base for all the heavy blocks of ice that would be thrown down there. But on the sides, I used a few layers of ligher cloth that were easy to install and roll out.
R value of Divinicell...no clue. Since it's not designed as an insulating foam, it may not even have ever been tested for those specs. Dunno. I used 4" of Homosote (polyisocyanurate), which has a high R value. Cheap at Home Depot.
If you have any need for flat panels of fiberglass that you could then cut up and use for myriad other purposes, this mat/roving combo material, laminated to whatever thickness on a flat piece of Melamine or some other surface that would allow release, would be perfect.
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