A system for curing lost circulation is made of fibers and a material able to stick fibers in a network when activated. Such activation can be temperature or pH change or both. The fibers can be metallic amorphous fibers, metallic non-amorphous fibers, glass fibers, carbon fibers, polymeric fibers and combinations thereof. The material can be a fiber coating or an additional material, for example polyvinyl alcohol, polyurethane and heat activated epoxy resin.