Assertion: asphalt | /r/ObjectUse | used as impregnating agent
Facets:
Source sentences:
text: It is not known definitely when felt was first substituted for sheathing paper or when asphalt was first used as the impregnating agent, but it is known that the first asphalt-prepared roofing, that is, roofing manufactured ready to apply, was marketed in 1893.