How to Seam Carpet
How to make an invisible carpet seam can seem impossible to some, but is well within reach with a few important points. Making a seam that is strong, yet looks good can depend on the cutting methods, the type of installation, and the type of carpet, among other things. Here we will discuss seaming cut pile carpets, such as a plush, that are stretched in over pad.
First, it is necessary to make sure both pieces to be seamed are going the same direction (all carpet pile has a certain “lay” to it where it will show a different shade depending on which way you look at it.) Next, you have to use a clean, “new” edge to seam together. You can’t use the factory edges, since they are tattered and damaged too much. For all carpets, if you can make a cut between rows it is preferred. I prefer using a loop pile cutter called a “cushion back cutter.” To use this tool it is helpful to use a darning needle or similar to separate the rows of pile about an inch from the edge of the carpet. Once you have a row to follow, make sure that it is fairly straight and you are not skipping rows.
To cut the seam with the row cutter, make sure your blade is new and is on the side of the row cutter that is against the seam edge. This makes sure you are cutting off the backing as close to the yarn as possible. Cut the carpet edge at about a five degree angle so that the backing is undercut very slightly so the seams will be as tight as possible. After you have done this to both sides of the carpet, put them in place so they are lightly butted together. If there are areas that are gapping, it may be necessary to over tighten the seam so it may be peaking in the areas too tight.
If it is not straight enough to pull both edges together as you seam them tight, you will need to recut it with a straight edge from the back. This method can be used from the beginning, but it is not preferred since it will cross rows of pile. However, with some carpets, it is the only way that can be used, since the rows are not straight enough, or the carpet has stitching that does not follow single rows. To cut with a straight edge, pull the carpet edge back so it is upside down with no bubbles and is lying with no tension. Place straight edge one inch or so from edge of carpet and cut with a carpet knife with a new blade. Do not put too much pressure on the knife or use too long of a blade so as to shear the yarn below. However, you do need to cut hard enough and deep enough to make the cut in one pass and as clean as possible so as not to make a tattered edge. After this, put the carpet seam together and prepare seam as before.
Place the seam tape under the seam and warm up the seaming iron. Put the iron into the seam on top of the tape at the end that allows you to do the seam in the direction of the pile. Move the ahead and put pieces together behind it working the piles together. Make sure the backing is tight, but not over lapping or too tight. Once you work it together and it is firmly pushed into the hot melt on the tape, place a board with a weight on it over the seam directly behind you. Work your way down the seam repeating this as you go and pulling the weighted board behind you so as it cools the board makes it lie flat. After you finish, do not walk on it or work the carpet until it cools.
