By Ray Thompson, Jr.
Many installers know how to heat-weld sheet vinyl proficiently. Unfortunately, many struggle to heat-weld linoleum flooring as they try to use the same method when heat-welding sheet vinyl. Doing so will cause a job failure and seams that will open up over time. The reason: different types of welding needs to be used. With sheet vinyl, you use a thermo-fusion process ‒ a combination of melting and fusion between the rod and the flooring material. With linoleum, a bonding process between the linoleum and the rod is used. The rod acts like a glue stick.
There are three major differences in heat welding sheet vinyl and linoleum: the groove is deeper, the rod doesn’t stick immediately, and the skiving has to be done while the rod is warm.
Photo 1 (see above): The seam must be cut slightly open. Make sure to allow time for the adhesive to dry. Unlike vinyl (pressure-sensitive adhesives) that you can heat-weld immediately, linoleum adhesives must be allowed to dry and set up overnight.
Photo 2: The grooving depth is another major difference. Sheet vinyl should be cut 1/2” to 2/3” of the thickness of the wear surface. With linoleum, the groove is cut down to the jute backing. The reason for this is cutting the groove depth down to the jute improves the bond between the rod and the linoleum. A shallow cut linoleum seam tends to open up over time.
Photo 3: After cutting the groove, set the temperature of heat gun next. The temperature settings are different between sheet vinyl and linoleum. The temperature setting for sheet vinyl is 650°-850°F (340°-450°C). The temperature for linoleum is 665°-750°F (350°-400°C). Make sure to consider the power supply, as well as the length and size of the extension cord when setting the proper temperature. Use a 5mm tip when heat-welding linoleum. This tip is a little larger than the tip used for vinyl (4mm). The 5mm tip allows for the rod to flow through without hanging up.
Photo 4: I prefer to use a narrow pre-heat tip to minimize scorching. The bond is not immediate, so don’t stretch the rod or pull on the rod as it will zipper out. Be sure the substrate is between 65°F-70°F (18.3°C–21.1°C) to make the welding process much easier.
Photo 5: With the first pass skiving linoleum, you will experience the second difference from vinyl. Do not let the rod cool down. Allowing the seam to cool down too much makes it difficult to skive. The first pass with the skive knife and the trim plate is almost immediate. The difference: the linoleum rod permits this. If you tried this with a vinyl rod, you would get severe concaving from the rod.
Photo 6: The second pass skiving should be done immediately after the first pass. Be sure the temperature on the job is not too cold as the final skive will become difficult if the job temperature is to cold. If you tried this with a vinyl rod, you would get severe concaving from the rod.
Photo 7: The finished seam is done. If the depth is down to the jute, then the temperature of the weld is correct, and the two passes of the skiving knife was done at the right temperature. The weld is something that will last for years.
Remember, the heat-welding process for linoleum is a lot different than that of vinyl flooring.