by menw » Tue Jul 24, 2012 7:57 pm
I agree that hardened (colored, patterned) "fabric" isn't often used for long-term outdoor purposes, but a kind of "fabric papier mache" technique could work if the item were strong underneath and also covered with a highly moistureproof clear sealer (like epoxy resin, layers of polyurethane, etc).
And "fiberglass cloth" is often saturated with polyester resin to make fiberglass resin items (including large ones) that are stiff and water-resistant, so suppose fabric could be added on top of the fiberglass cloth layer, or be used instead if over that armature I mentioned before. (Plain papier mache items can also be created to be very strong and very moisture-resistant, but most people don't go to those lengths.)
It could also be that a layer of fabric was placed (with resin or polyurethane, etc) over another kind of material like hypertufa, Quikcrete, etc, rather than over fiberglass cloth or just over a chicken wire, etc., armature.
There are all kinds of materials sold as "glues," and many things are adhesive even if not sold specifically as glues. Even regular 'glues" vary a lot in their characteristics though so hard to say which kind of glue you or she may be assuming was used. One commonly-used sealer and clear finish used for papier mache and various other materials is permanent white glue (PVA like Elmers GlueAll, etc) thinned down with water--or a "decoupage medium" like ModPodge which is the same thing. But that will not be highly-resistant to water and humidity if the exposure is constant or heavy (as might be true outdoors for very long). And it won't be as tough as some other clear sealers/finishes which will be more resistant to scratching and later cloudiness too. That glue/water layer could be covered with something tougher though, like resin or polyurethanes, etc.