Can confirm, before reinforcing my back armor fell of the chair while painting and it shattered back into a couple pieces. You just need more surface area to get a good bond. Ideally with some reinforcement to prevent shearing.
I can't recommend fiberglass though, at least not the loose sheets I bought. They came apart when I was applying the resin and turned into loose fibers/splinters. You do NOT want fiberglass splinters anywhere near you, and sanding them requires a LOT of PPE.
That's why I switched to bug netting/tulle fabric. Easy to cut into the right shape with scissors, tack it down with a dot of superglue and then cover with one or 2 layers of resin. Much safer and (hopefully!) strong enough.
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