Paraloid B-72 is a non-yellowing acrylic thermoplastic resin used by conservators to bond ceramics, glass, fossils, and piano hammers, reversible with acetone.
Key Takeaways
Chemically an ethyl methacrylate-methyl acrylate copolymer; stronger and harder than polyvinyl acetate but less brittle, with more flex tolerance at joins.
Primary solvent is acetone; mixing in ethanol or toluene adjusts working time and final hardness/flexibility in the cured film.
No plasticizers required for long-term stability, unlike cellulose nitrate adhesives; fumed colloidal silica can be added to improve workability and stress distribution.
Stephen Koob at the Corning Museum of Glass pioneered casting B-72 into solid sheets as a transparent fill material for glass losses.
Full reversibility is the key conservation property: acetone dissolves cured B-72, making repairs undoable without damaging substrate.
Hacker News Comment Review
The clearest practical signal came from a commenter who used B-72 to consolidate surgical bone at a 1:8 resin-to-acetone ratio, one-hour soak, confirming the consolidant use case outside museum settings.
Commenters probed adjacent applications: 3D-print soluble supports (comparison to HIPS/d-limonene) and natural specimen hardening (shells, sand dollars), neither answered with data in thread.
No one benchmarked B-72 against MMA structural adhesives on strength or substrate compatibility, leaving the performance ceiling unclear for structural vs. conservation loads.
Notable Comments
@mooman219: preserved own surgical bone using 1:8 B-72/acetone soak for one hour; “suddenly they’re solid and strong.”
@0xbadcafebee: sharp one-liner framing: “stronger, harder, less brittle, clear wood glue you can dissolve with acetone.”
