When double-stick carpet installation was first introduced, there was not a lot of information available to installers. Over the years through trial and error, the industry has gotten a much better understanding of what works and what doesn’t on double-stick applications.
When this type of installation method was first introduced, there were no double-stick- specific, hot melt seam tapes available to construct the seams. The most common seam sealing method was the same as a direct-glue seam sealer application. A manufacturer recommended seam sealer with a 1/8” bead along one edge, a hot glue application, or seam sealer tip, which applies to both seam edges are still being used in double stick applications (Photo 1). Through all the developments of double-stick hot melt tapes, you are now seeing several different types of seam tapes available to the installer.
Hot melt tapes have proven to be a better way to construct double-stick seams; they have more tensile strength than just using a bead of seam sealer, and also allow for more vertical movement.
This hot melt seam tape designed for double-stick applications has a pressure-sensitive adhesive applied to the backing of the seam tape with a releasable paper so the tape won’t stick to itself. Center the seam tape between the two seam edges; once you get it in place, start at one end and slowly peel the white release paper and stick the seam tape to the cushion (Photo 2). Now use an appropriate seam sealer and seal “both edges.” Once the seam sealer has dried, fold back the two panels and spread adhesive with the proper-notched trowel. When applying the adhesive, you’ll notice that this seam tape has an exposed edge with no thermoplastic hot melt adhesive (Photo 3). Spread adhesive just under the tape as well as the exposed area on top of the tape (Photo 4). This will minimize any potential of bubbles from appearing along the tape; this is even more important with rolling loads such as office carts. Construct your seam with your seam iron, seam roller, and seam weight.
The next seam tape is one that was designed to be used with the Kool Glide seaming system. The tool does not get hot like a traditional hot melt iron; instead it uses radio waves to heat the hot melt tape with a foil backing. The tape also has pressure-sensitive adhesive on the back of the seam tape with a releasable paper. Center the tape, peel the release paper, and apply pressure to bond to cushion (Photo 5). Trowel on adhesive and once again you may note that the thermoplastic does not extend all the way to the edge. Apply adhesive up to the ridge of thermoplastic hot melt to insure a good bond. Place your carpet and construct the seam with the Kool Glide tool The tool behind the Kool Glide is called the Seamer Down. It is not a seam weight, but rather, draws air upward with the vacuum head that is attached, which dissipates the heat away from the seam more quickly than a traditional seam weight. (Photo 6).
This hot melt seam tape is one I like to use when I have small fill pieces. I hate trying to place a small fill piece into adhesive and having the potential of getting multi-purpose adhesive on the face yarns or worse, on me.
This hot melt tape comes from the rug designer/fabricators side of the industry. It has no backing, just thermo-plastic hot melt and a scrim. There is a carrier release paper applied to the back of the seam tape (Photo 7). Once the seam has been constructed, the carrier release paper is removed (Photo 8), adhesive is applied to the cushion, and the main breadth and seamed piece are placed into the adhesive with no fuss and no mess. Note that the seam is a cold seam meaning that the tape was cool before placing into adhesive.
Constructing a hot melt seam with a seam iron over multipurpose adhesive is not recommended.
Now in writing that last sentence, let me introduce you to a new seam system that utilizes a thermoplastic hot melt glue gun (Photos 9 and 10). The difference between the glue gun and seam iron is that the glue gun won’t be applying 300-plus degrees in a three-inch wide by ten-inch long hot plate. And, with the use of a tape system designed for a hot melt glue gun, it makes for a practical application. The tape on this system is a scrim/mesh tape with a special carrier tape placed in the center where the hot melt is applied. Lay out the breadths, trim and seal seams, and fold one panel back. Before folding the second panel, take the seam tape alignment tool (donut) and a felt marker. Set the donut down next to the panel, now, with the felt tip marker, place a mark on the cushion but remember to place the felt tip marker on the side of the donut next to the seam edge (Photo 11).
Once you have placed the tape into the adhesive, continue to finish gluing the other half that was folded back; allow proper open time of the adhesive, fold carpet into adhesive (Photos 12 and 13). The reason for placing the mesh into the adhesive is that the scrim/mesh combined with multipurpose and the hot melt to bond the seam edges makes for a very strong seam. The tip on this seam system displaces hot thermoplastic from two sides to coat the two seam edges. The center carrier tape bonds to the excess hot melt from the hot glue gun to finish the bonding process of carpet to the scrim.
Before placing the tip between the two seam edges, on a piece of scrap carpet, squeeze out some hot glue to get the hot glue flowing smoothly out of the gun. Make sure the tip is clean so that there is no excess to minimize hot melt on face yarns. Place the glue gun tip into the seam. Slightly elevate the back of the glue gun, you may want to experiment a bit to get the feel of what angle works best for you to achieve 100 percent coverage of the seam edges without squeezing out too much hot melt adhesive. Squeeze the trigger, get a smooth flow, and pull towards you. “Pinch” the seam together as you pull the hot glue gun. (Photo 14) When you get to the opposite wall, it will be necessary to pull the hot glue gun tip out when you get to within two feet of the finish wall. This is where you need to be a bit careful, as you do not want to get hot melt adhesive on the face yarns. Stop the flow of hot glue and pull the hot glue gun straight up and out. Reinsert the hot glue gun at the ending wall and pull towards where you stopped. When you get to within two inches of the spot you stopped at, gently squeeze the trigger of the hot glue gun and when you get to where the seam is bonded, once again stop the flow of hot melt and pull straight up.
With the specialty adhesives, seam tapes, and knowledge now available, the installer has the ability to have a successful double-stick installation.