Dropback definitions

Dropback

A reduction in the softening point of bitumen that occurs when bitumen is heated in the absence of air.
Found on http://www.rbroof.com/glossary-of-terms

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dropback

a lowering, as of prices or standards, esp. to a previous level: Auto manufacturers requested a dropback in emissions standards.
Found on https://www.infoplease.com/dictionary/dropback

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