Why are furniture parts often sanded again after glue has set?

In the furniture industry, parts are often returned to the machine department for sanding after the glue has set to address specific construction requirements that could not be performed prior to assembly. This process allows manufacturers to effectively sand joints and shape edges that were inaccessible or required the stability of the assembled piece to be finished accurately.1

Additionally, the final assembly stage involves cleaning the completed article to remove any excess glue, followed by a final inspection and hand sanding to ensure the surface quality meets production standards before staining and polishing.1