How To Seam (aka Glue) Solid Surface
Fabrication manuals from the solid surface manufacturers often show fancy and expensive tools that are used to help with seaming. Those expensive tools and methods are good best practices when you are producing a lot of seams. If you are not, then the following tools will more than suffice:
Make six or eight 1” x 2” clamping blocks from wood or scraps of solid surface. Attach these blocks with hot melt glue about 2” from the edge of the pieces to be seamed.
Lay down one or two 2” wide strips of plastic tape on the surface under the area of the glue seam for protection from glue drip onto the surface. Place paper on the floor to catch any drip through.
Do a dry run to make sure the sheets will mate evenly and then separate them by about 1/2” in preparation for adding adhesive
Always dispense a small amount of material from a new cartridge before adding the mixing tip to be certain that both parts of the adhesive flow. After the tip is attached, squeeze a bit more through the tip and then start applying to surfaces to be bonded. An adhesive gun that is dripless helps avoid making a mess.
Apply two 1/4" diameter passes of adhesive, one pass on each of the surfaces to be mated. This will eliminate “soft spots.” If there is a place on the first pass where the adhesive was not mixed correctly, then the second pass, which will not likely have that happen in the same location, will ensure there will be catalyst available to cause hardening of the adhesive.
Apply Bar Clamps
Span the blocks with the clamps and tighten. DO NOT OVER TIGHTEN as it will cause a weak joint. Allow 30 to 45 minutes for the adhesive to set. Remove the blocks by squirting denatured alcohol at their base. This will soften the hot glue so they can be safely removed.
Remove Excess Adhesive
Sand away the excess adhesive and feather either side out about six inches using 120 grit abrasive. Next, sand out to about 12 inches using 180 grit and then sand the seam area to blend into the final finish with 280 grit or finer.
Add a Seam Plate
As a best practice to protect your seam integrity, use a seam plate on the back side of the material to reinforce the seam holding the two sections together.Sand the surfaces of the two pieces in preparation for attaching the seam reinforcing plate. The plate is solid surface of the same color or a scrap of a lighter color since darker colors may produce a shadow effect. The seam plate is a 4" wide piece with a 45 degree angle cut on both sides to regulate heat dissipation and minimize the starting of a crack. Cover the plate with adhesive and apply over the seam with some clamping or downward pressure from weighted objects.
View the Finished Seam
The seam will be either very inconspicuous or will disappear altogether. The location of the seam in the picture is undetectable, but we know where it is because of the daub of excess adhesive that shows on the edge of the sheet in the lower center of the picture.