Hot-Melt Seaming: Iron Temperature, Tape and Technique

A good seam starts before the iron comes out: straight cuts, the right tape, sealed edges, and a plan for where the seam goes. The iron is the last step, not the first.

Plan the seam

Keep seams to a minimum. When possible, run seams the length of the room and keep main traffic parallel to the seam rather than across it.^[1] Keep them out of doorways and away from light that rakes across them, too.

Cut straight edges

Gaps and overlaps at the edge show through no matter how well you iron.

• Cut both edges so they butt tight with no gaps and no overlap. Row-cutting both edges is preferred, though other trimming works better on some carpet.^[1]
• Use a row finder to open the row and a seam cutter or row-running knife to follow it on cut pile. On loop pile and berber, cut between rows.
• Check pile direction. Both pieces must lay the same way.

Tape and edge sealing

The tape holds the seam together, and edge sealing keeps it from fraying.

• Use premium tape with high tensile strength and an adhesive band at least 2-3/4" wide.^[1]
• Where the backing needs it, seal both edges with seam adhesive covering the primary and secondary backing, without getting it on the face yarn. Sealing keeps the edge from fraying and delaminating.^[1]

Step by step

With the edges cut and sealed, the seaming itself is about steady heat and pressure.

1. Center the tape under the seam, adhesive side up.
2. Heat the iron to the setting the tape and iron makers recommend. Test on a scrap: the adhesive should melt fully without scorching.
3. Set the iron on the tape under the seam and let the adhesive melt. Slide it forward slowly and steadily.
4. Right behind the iron, press the carpet edges down into the melted adhesive and push them together. Use a seam roller or tractor to set the backing into the glue.
5. Put a seam weight on the finished section while it cools.
6. When cool, brush the pile across the seam and trim any stray fibers.
7. Don't stretch across a seam until the adhesive has fully cooled and set.

Common mistakes

Seam failures usually come down to heat, speed or skipping a step.

• Iron too hot or too slow. Scorches the backing and can melt face fibers.
• Iron too cool or too fast. The adhesive doesn't wet the backing and the seam lets go. See Peaked and visible seams.
• Skipping edge sealing. The seam holds but the edge frays and opens later.
• Seams across traffic or in doorways. They wear first and show first.

Tools we carry

These are the irons, tape and seam tools we carry.

• Irons: Roberts 10-282G-2 Everclean, Crain No. 905, Taylor 890, Taylor 893L Lighted
• Seaming tape, Gundlach 612-SW Seam Weight, Roberts 10-124 6" Cut Pile Seam Roller
• Seam cutters and row finders and all irons and weights
• Iron parts: Seaming iron not heating or overheating

References

1. CRI 105: Standard for Installation of Residential Carpet