Paraloid B-67 is an isobutyl methacrylate polymer that dries harder than Paraloid B-72.  This resin is soluble in white spirit, acetone, alcohols, toluene, xylene and glycol. It can be used as a protective barrier for fossils, or as a coating in archival marking. 

Industrially, it is used as an impregnative barrier for rust-prone metals to protect them, e.g. in automotives.

Paraloid B-67 is hydrophobic, providing excellent water resistance (a suitable sealant following Pyrite Decay treatment in Pyrite Stop). With this hydrophobic (water-repelling) property it is a better candidate for this than Paraloid B-72.

It can provide an excellent barrier against both atmospheric moisture and gas (oxygen); with much lower permeability than Paraloid B-72. Storage in low humidity environments remains essential, but Paraloid B-67 can provide an extra barrier layer between atmosphere and fossil. 

Paraloid B-67 is also removable as it is redissolvable in solvent, and so it can be used and then removed prior to another round of treatment in Pyrite Stop (ethanolamine thioglycollate).

We recommend dissolution in acetone for this application for the clarity of solution, speed of evaporation and impregnation capabilities. For archival marking, dissolution in white spirit is the most common to prevent running of ink. Paraloid B-67 does take a long time to dissolve in solvent, so be patient. You can use the same calculations and mixing instructions as for Paraloid B-72 described here in this article.

Prolonged exposure to UV light will cause yellowing, but in thin coatings this is unlikely to be noticeable. It can be removed with solvent and reapplied. 

Not to be confused with the more commonly used Paraloid B-72, which is chemically very different, and used as an adhesive and consolidant. 

In archaeology, it is used to stabilise bone, clay, stone and other fragile artifacts. It is used outdoors for artefacts and monuments that require a hydrophobic (water repelling) coating.