If you've got an old wood deck or maybe a wood column that is starting to show signs of age, one way to stop the decay is to use a wood hardener. This product seeps into the pores of the wood and hardens after two to four hours, keeping the wood intact. Using a wood hardener takes a bit of preparation to do correctly, but otherwise it's a straightforward process.
Identify the area on the wood you want to harden. Scrape away any loose or decayed wood using a putty knife, working until you get to wood that is in reasonably good shape. Make sure there is no grease, oil or dirt in the affected area.
Shake a can of wood hardener. Pour some of the hardener onto the surface of the wood and spread it out around the area using a paintbrush.
Apply a second and third coat using the paintbrush for extra strength, applying coats until the wood has a shiny surface.
Let the wood hardener dry for two to four hours. Sand, paint or stain the surface, if you wish, to finish the project.