Many installers know how to heat weld vinyl proficiently, but struggle when it comes to linoleum. The reason it is such a struggle is that it is a different type of welding. With vinyl you have a thermo-fusion process; that is, a melting and fusion between the rod and the material. With linoleum the process is completely different. The linoleum and the rod is a bonding process, not a fusion process. The rod acts like a glue stick. With linoleum, the groove is deeper, the rod doesn’t stick immediately and the skiving has to be done while the rod is warm.
Following is the step-by-step process to follow in order to ensure that the heat-welding is done efficiently and correctly.
Photo 1: The seam must be cut slightly open and time must be taken for the adhesive to dry. Unlike vinyl adhesives that are pressure-sensitive and can be heat welded immediately, linoleum adhesives must be allowed to dry and take overnight to set up.
Photo 2: Grooving is one of the major differences from vinyl. With linoleum the groove is cut down to the jute backing. The reason for this is the depth down to the jute improves the bond between the rod and the linoleum. Shallow-cut linoleum seams tend to open up.
Photo 3: Once the groove is cut, it is time to set the heat gun. Consideration must be given to the power supply and the length and size of extension cord. A 5mm tip should be used, which is a little larger than the tip used for vinyl and allows for the rod to flow through the tip without hanging up.
Photo 4: I prefer the narrow pre-heat tip, which produces less scorching. Still, the bond is not immediate, so don’t stretch the rod or pull on it, as it will zipper out. Be sure the substrate is between 65 – 70 degrees Fahrenheit (18.3 – 21.1 degrees Celsius) so the welding will become much easier.
Photo 5: With the first pass skiving you will experience the second major difference from vinyl. That is, do not let the rod cool down. Do not let a long seam allow the rod to cool too much, which will make it much more difficult to skive.
The first pass with the skive knife and the trim plate should be almost immediate. The difference is the linoleum rod permits this. If you tried this with a vinyl rod you would get severe concaving from the rod.
Photo 6: Second-pass skiving should be done immediately after the first pass. Be sure the temperature on the job is not too cold, otherwise the final skive can become difficult. The skive should be smooth and continuous to prevent any chatter marks.
Photo 7: The finished seam is done; that is, if the depth is down to the jute, the temperature of the welder is correct, and the two passes of the skiving knife are done at the right temperature. If done correctly, the weld will last for years. Just remember, linoleum is very different from vinyl.