Carpet patching is a seemingly simple procedure that takes years to master. It takes many years to master this because there are so many different carpet patching situations that you can find in different homes. Patching carpet is when a damaged piece is removed, and a new piece is used to replace it. Many different things matter at this point. Carpet grain direction is one, also carpet color, and sun fade, or dye loss from walking. All of these things are matched, and then the patch is affixed permanently with a iron and seaming tape. It will not be able to be removed without a razor. Vacuum all you like.
