"A putty knife is a specialized tool used when glazing single glazed windows, to work putty around the edges of each pane of glass. An experienced ...
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glazer will apply the putty by hand, and then smooth it with the knife. Modern insulated glazing may use other ways of securing the glass to the window frame.
A spackle knife (called a scraper in British English, also known as a spatula in American English) is also commonly called a "putty knife",[citation needed] and is used for scraping surfaces or spreading material such as plaster in various construction trades. Widths from 11⁄4" to 5" or 6" are commonly available. Wider-bladed knives up to about 12" are used for sheet rocking. Larger blades are made, but generally lack the stability of the smaller blades and do not make a perfectly flat surface." - (en.wikipedia.org 18.11.2021)