The recess-scribed seam is the most demanding and widely use of all the resilient seaming techniques. Many installers have a difficult time with the entire recess scribing process for two reasons; setting of the recess scriber and the cutting process. In this article we will examine both of the techniques to accomplish both.
Setting the Recess Scriber
Many installers use the trial and error method of setting a recess scriber but there are several methods used by other installers that aid in the setting of the recess scriber. The requirements of most manufacturers specify a net seam, unless the seam is to be heat welded and then the seam should be cut slightly open.
For a net seam, take a scrap of material about 6-inches square and make a 2-inch knife cut in the material. The cut needs to run the machine direction (the direction of the roll curl) of the material. The knife cut needs to be as straight up and down as possible; any bevel in the knife cut will cause the setting to be off.
Place the lower guide section of the recess scriber into the knife cut as illustrated; hook the ball on the guide section firmly on the lower cut edge of the material. Be sure to keep the recess scriber flat on the material. Then move the needle of the pin vise down to about one quarter the thickness of the material. Be sure your scribe needle is sharp. Slide the pin vise up to the cut edge of the material to the point that the needle touches the edge of the material. Carefully and firmly lock the pin vise. When locking the pin vise, care must be taken not to move the needle out of position. Once tightened, double check the setting of the needle with the scrap of material to ensure the setting is correct.
Recess Scribing the Seam
Remove a minimum of ½” of salvage off the edge of the material. This can be done with a straight edge or an edge trimmer (as illustrated). Failure to remove the salvage edge will affect the quality of the seam. The seam edges on both sides of a seam need to be freshly cut and square.
Once the first width of material is prepared and placed into position, overlap the edge of the second width, over the first width, a minimum of ½”. Lap or tube the material and apply the adhesive to both sides of the seam. Place the material into the adhesive and roll the material with the recommended weight roller. Keep the roller about 6 inches from the seam. Insert the recess scribe around the second width of material, locking the guide ball on the prepared edge of the first width of material. Be sure the needle is set to allow the scriber to be moved into position without marking the material. Hold the recess scribe at a right angle to the seam with guide ball held firmly against the prepared edge of the first width. Then with a gentle downward pressure pull the recess scriber toward you. Make a short scribe and cut the material too be sure the setting is correct. It is a great habit to get into checking the scribe every time you use it. It prevents costly mistakes. Care must be taken not to apply too much pressure on the needle. The needle is designed to mark the material. Excess pressure causes the needle to tear and rag the material’s surface; this is why it is imperative for the needle to be sharp and the pressure to be light. The recess scriber is a marking tool and not a cutting tool. The scribe mark should only serve as a guide for the tip of a sharp cutting tool.
After the material is lightly scribed, place a scrap of material beneath the edge of the material to be cut. This prevents any damage to the material beneath. Use a freshly sharpened blade or a new blade, holding the knife as straight up and down as possible; make a light pass with the knife. The objective is to change the scribe line to a cut line. A light pass allows the knife point to follow the scribe mark. Excessive pressure causes you to lose control of the knife allowing the blade to wander out of control.
After the salvage is removed take a damp white rag and wipe the cut edge and hand roll with a steel hand roller. The damp rag helps remove any debris and also helps lubricate the edges, making them go together easier. The hand roller should be used with a moderate pressure, forcing the material down into the adhesive. Be sure to roll the material out to where the floor roller was used. Avoid using too much pressure as it tends to displace the adhesive and compromise the bond.
Finally, after the seam is rolled, the seam needs to be de-burred. Use a damp white rag to wipe the finished seam and start the de-burring process. This can be done with either the back of a knife or with a scrap of material held face-down. When dry, it is a good idea to apply a coat of polish to the seam to help keep the seam clean.
A recess scribed seam can be a work of art or a disaster. It all depends upon the technique you select and how much attention you pay to detail.