A “good” solvent—one with a strong affinity for the cyanoacrylate monomer and polymer—turns out to be unsuitable for Primer B. Such a solvent will either dissolve the cyanoacrylate polymer or absorb into it and soften it, neither of which is good for subsequent adhesion. When the solvent can dissolve the polymer, the polymer layer that forms tends to be dense, stiff, and glossy, making it unsuitable for an elastic joint and offering weak binding to adhesives and coatings. When the solvent can absorb into the polymer and soften it, the polymer layer that forms tends to be somewhat porous and flexible, but it still provides limited grip to adhesives and coatings.