Many products are available to complete an "invisible" seam.
Seaming is a very important part of solid surface fabrication and the inconspicuous seam is a great selling point. I like to think about seams being invisible, and this is not hard to do. The one thing I recommend is putting the two pieces being seamed together to check the fit — before you glue them.
There are several ways to prep a seam:
• Panel Saw — Your saw must be in perfect running condition with a very good solid surface cutting blade. The one thing to watch for is bowing in the sheets after you rip them. The sheets can have stress in them that can be released in this process, so check to make sure they stay straight.
• Mirror Cut — Using a router, space the two pieces being seamed about ⅜ in. apart and rout with a ½-in. bit through the two pieces. If you are seaming a top that is 48 in. wide and 120 in. long, you need a seam jig to accomplish this.
• Wavy Cut — Use a router with a wavy base and bit for this process. It requires a dedicated router with a special base that has a step in it. You will also need a straight edge to ride the base against. You rout one side of the seam with the thin side of the base and the other side of the seam with the thick side. For me, with my short arms, this works best. Also, the wavy seam allows more gluing surface and helps align the face of the seamed pieces. You must put a seam strap under the two pieces being seamed. A trick I learned is to saw a relief in one side of the strip — about 1/₃₂ in. Oftentimes the thickness of the material will vary a little and you want the face of the seam flush. Fill the gap on the seam block with plenty of glue to get full glue coverage.
• CNC Router Cut — For in-shop seams, we use a ⅜-in., 3-flute bit to ensure a nice smooth cut. Field seams will have to be rerouted after the edge is glued on. When we cut out our top and build up strips, we use a special ¼-in. bit running at 24,000 rpm and 1,000 in. per minute (ipm).
All of the above ways to prep a seam work. Again, just make sure to check the fit before gluing the pieces together. At our shop, if a seam shows after gluing, we rip it apart and redo it.