Heat Welding Linoleum Floors
Linoleum should not be mistaken for sheet vinyl flooring which is often called linoleum. Although they may be similar in appearance, they are distinctly different in composition. Sheet vinyl is composed of PVC and various other synthetic and natural products, linoleum is composed of mainly natural products such as linseed oil, cork flour, wood flour, pine resin and jute backing.
These differences will affect installation and maintenance recommendations; failure to understand and follow these recommendations can lead to expensive and unpleasant results.
Heat welding of linoleum is the popular seam treatment for commercial settings, where the majority of linoleum is specified and installed.
The tools and techniques for heat welding linoleum are similar for heat welding sheet vinyl flooring; however there are some distinct differences.
Because of this difference most manufacturers recommend heat welding at lower temperatures than sheet vinyl flooring to avoid melting the linoleum welding rod into a liquid, and to prevent charring the linoleum flooring at the seam.
The recommended temperature ranges are from 300 to 450 degrees Celsius, however practice with a scrap piece of material is highly recommended at the start of each job to ensure proper heat settings and speed of movement are established.
The first step to a quality heat welded seam is a well cut, well bonded seam. Be sure to follow manufacturer's recommendations for seam cutting, and the amount of time needed after adhering the linoleum for the adhesive to set before heat welding. The time will vary from 10 to 24 hours depending on the manufacturer.
Proper grooving of the seam is critical to a successful weld; the groove must be centered on the seam, of the proper width for the welding rod, and grooved to the correct depth of at least 2/3 of the thickness of the linoleum. For example most manufacturers recommend grooving 2mm and 2.5mm linoleum down to the top of the jute backing. This will provide a good surface for the welding rod to bond with. A groove that is too shallow will result in the welding rod pulling out when trimmed.
Hand groovers will work on short seams, however they can be difficult to use as linoleum chips can clog the blades, preheating the seams with a heat gun can help to prevent this but generally it is impractical to hand groove long seams.
Electric groovers will work well on linoleum providing they are well maintained with a sharp blade (to avoid chipping the edges of the groove) Complications can be encountered if the groover does not have a "floating base" or the ability to adjust to deviations in substrate flatness. Nothing is harder on a grooving blade than cutting into a concrete substrate. Also an electric groover with a non functioning dust bag can lead to an invitation to leave the job due to linoleum dust clouds.
Non electric rolling groovers like the new Marmo Groovers work very well, even accommodating curves and circles. Some rolling groovers will require preheating the seam to prevent the blade from clogging; sharp blades are a must to prevent chipping the groove edges.
Whether using an automatic welder or a hand held welder; welding linoleum requires the correct temperature and using slight pressure at the tip to force the melted weld rod into the groove. Welding at a consistent, steady pace down the seam is critical to a solid, strong seam.
Moving too slow will produce a charring of the linoleum, a brown to black color at the seam. Moving too quickly or inconsistently will produce a "cold weld" or "cold spots" that will result in the welding rod pulling out of the seam when skived or trimmed.
Heat welding linoleum has become easier thanks to the roller guide. This tool attaches to a hand held welding gun and guides the welder in the groove at the proper position resulting in a more consistent weld. (See Photo 6)
Skiving is the processes of trimming the weld rod flush to the surface of the linoleum. Traditional skiving tools are quarter moon or spatula knives and a trim plate. Skiving should be done in two passes, unless using a one pass tool as shown here.
The first pass removes the top half of the weld rod decreasing the resistance on the blade when making the final pass flush to the linoleum surface.
Linoleum manufacturers recommend making the first pass while the rod is still warm, if the first pass is made after the rod has cooled any area of the welded seam that is not well bonded will release and the weld rod will pull out of the groove. It is not uncommon to see an installer following the welder making the first skiving pass.
To get a clean final skive; allow the weld rod to cool completely. The new Turbo Plane replaces the traditional two pass method, it skives the weld rod in one pass thanks to its double blade design. Adjusting the plane leaves a smooth and flush finish every time. (See Photos 8 and 9)
Once the welded seam is completed, some manufacturers recommend applying a coat of commercial floor polish over the weld to help keep it clean until the floor receives protective maintenance.
With recent improvements in heat welding tools it is easier than ever to weld linoleum with greater consistency, whether straight or radius seams. The tools ergonomic design greatly reduce stress and fatigue on the installers using them. They also reduce the time needed to master their use.