Call it from the install(f)unction of your foreign library nonetheless, so that the type exists as soon as the library is loaded. Until it is registered blob_type_property/2 cannot report the type and set_blob_type/2 cannot give it a collection budget (see section 12.4.10.3), which is of little use once the blobs it should bound already exist. It also settles the type's place in the standard order of terms, which is assigned on registration and otherwise depends on which type happens to create a blob first.