I ve seen where after you stick the laminate to the counter you trim it with a router.
How to join laminate countertop corners.
Mark the miter angle on the back of the laminate countertop.
Spread contact adhesive on the countertop substrate and both sheets of laminate.
Sand down any rough edges with a sander or file.
For joining in a corner the pieces should be cut at a 45 degree angle.
Measure and cut the laminate countertops to the desired size.
Place the two sections of countertop on top of the sawhorses so the laminate side is facing up and the corners are together.
Cut the tops to length and apply glue to the laminate ends.
However carpenter s glue sets up more quickly.
Before you join the pieces mark the ends where you need to cut them to length.
Either glue works well.
Apply yellow carpenter s glue or liquid hide glue to both edges of the mitered joint and reposition the two sections.
Remove the burr with a file so the laminate will glue down completely flat.
I haven t seen anything that shows how to trim tight spots such as the side edge of the laminate up to the wall.
Using the straightedge draw a line on the countertop between the l s inside and outside corners.
Use an angle square to determine the perfect 45 degree angle.
They let you position the sheet exactly before gluing it down.
When it dries set a sheet on dowels placed on the substrate.
You ll end up with a small burr on the bottom edge of the laminate.
Check that the fronts and backs of each piece align with each other.
Check the underside of the miter joints to ensure the mortise joints align as well.
In most of the videos i ve seen the counters are removed or if they re not removed they simply show how you trim the front edge with a router.
Mark a straight pencil line along this straight edge.