What Paraloid B-72 Is
Paraloid B-72 is a synthetic acrylic resin made from a copolymer of methyl methacrylate and ethyl acrylate. It was developed specifically for conservation purposes and has become one of the most widely used protective coatings in museums and conservation labs around the world. The material is manufactured by Rohm and Haas and is recognized as an industry standard.
Reversibility and Safety
One of the most important properties of Paraloid B-72 is that it is reversible, meaning conservators can remove it later without damaging the original object underneath. It can be dissolved and removed using organic solvents like acetone or toluene. This reversibility makes it ideal for conservation work because future conservators can change or improve the treatment if needed.
Optical and Chemical Properties
Paraloid B-72 is completely transparent and colorless, so it does not change the appearance of the objects it protects. It does not yellow or discolor significantly over time, even when exposed to light and air for many years. The resin is also chemically stable and resistant to moisture, making it effective at protecting artifacts from environmental damage.
Common Conservation Applications
Conservators use Paraloid B-72 to protect many types of objects, including paintings, sculptures, ceramics, glass, stone monuments, and archaeological artifacts. It can be applied as a thin protective layer that shields the object from dust, pollution, moisture, and ultraviolet light. The coating is flexible enough that it will not crack or peel easily as objects expand and contract with temperature and humidity changes.
How It Is Used
Paraloid B-72 is supplied as solid beads or pellets that must be dissolved in an organic solvent before use. Common solvents include acetone, toluene, or xylene, and the conservator chooses the concentration based on the application. It can be applied by brushing, spraying, or dipping the object, and it dries to form a clear, hard protective film.
Limitations and Considerations
While Paraloid B-72 is highly valued in conservation, conservators must ensure proper ventilation when using organic solvents because they produce harmful fumes. The coating can also be sensitive to some solvents, so it must be carefully chosen based on the specific object being treated. Over time, if the coating becomes dirty or damaged, it may need to be removed and reapplied. 
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