text: An open seam occurs when there is a separation between one of the ribs and either the front or back plate of an instrument. This can be caused by a sudden change in humidity. While open seams are extremely common and relatively simple to resolve, you should entrust the repair to an experienced luthier. The seam, which is mended with melted hide glue, can sometimes be closed up in as little as four hours, but most luthiers will allow the glue to set for at least a day.