Oops. When using loose tenons on a recent project I cut the mortise on the wrong face of a board. Has this happened to you? Don’t panic. We can make that mortise nearly invisible with a Dutchman, a woodworking wood for a plug. Why is it called a Dutchman? I don’t know…just because.
Using the bandsaw, I cut a piece the right thickness to plug the mortise. I used hand tools and hand sanding to refine the size and shape so the plug was a good tight fit for the errant mortise. This included slightly rounding the ends to match the shape of the mortise. Be sure the material you’re using for the Dutchman matches the project piece in grain and color.
Apply glue in the mortise and tap the Dutchman in, leaving it proud of the surface.
After the glue is dry tape off the area surrounding the Dutchman and cut the plug flush to the tape. The tape protects the surrounding surface from saw marks. A fine pull saw works great for cutting the plug.
After a little sanding the incorrectly placed mortise is nearly invisible, I’ve salvaged my project piece, and life is good again.