Many installers know how to heat weld vinyl proficiently, but struggle when it comes to heat welding 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 — a melting and fusion between the rod and the material. With linoleum, the process is completely different. The linoleum and the rod are a bonding process with the rod acting like a glue stick. There are three major differences; the groove is deeper; the rod doesn’t stick immediately, and the skiving has to be done while the rod is warm. The following are the steps for successful linoleum heat welding.
The seam must be cut slightly open and time must be allowed for the adhesive to dry. Unlike vinyl (pressure sensitive) adhesives that can be heat welded immediately, linoleum adhesives must be allowed to dry and set up overnight before welding.
Grooving is another major difference from vinyl. With linoleum, the groove is cut down to the jute backing. The reason: with the groove cut depth down to the jute improves the bond between the rod and the linoleum. A shallow cut seam tends to open-up.
After the groove is cut, it is time to set the heat gun. Make sure to consider the power supply and the length and size of extension cord. A 5 mm tip should be used on the heat gun. This tip is a little larger than the tip used for welding vinyl and allows for the rod to flow through tip without hanging up.
I prefer the narrow pre-heat tip as it produces less scorching. Be careful as the bond is not immediate, so don’t stretch or pull on the rod as it will zipper out. Make sure the substrate is between 65° – 70°F (18.3° – 21.1°C) so the welding will become much easier.
With the first pass skiving you will experience another difference from heat welding vinyl. Working with linoleum, you should not let the rod cool down. Also, do not let a long seam allow the rod to cool too much. Allowing the seam to cool too much will make it difficult to skive. The first pass with the skive knife and the trim plate is almost immediate. The difference is the linoleum rod permits this. If you attempt this with a vinyl rod, you would get severe concaving from the rod.
Second pass skiving should be done immediately after the first pass. Be sure the temperature on the job is not too cold. If the temperature is too cold, the final skive will become difficult.
The finished seam is done. If the depth is down to the jute, the temperature of the welder is correct, and the two passes of the skiving knife is done at the right temperature your proper linoleum weld will last for years. Remember, that linoleum is a lot different that vinyl.