Heat-Forming Laminate to Fit Curves

Heat is the key to a good curved edge on a laminate countertop. January 9, 2007

Question
When I am laminating a 2-1/2" radius on an outside corner of a countertop, using contact cement, I often experience the laminate not bonding at the straight points. Some people like to fill these areas with Bondo or squeeze a little superglue in there to get it to bond. Why does this problem happen and what are the solutions? I am thinking about white gluing the radius areas only.

Forum Responses
(Laminate and Solid Surface Forum)
From contributor J:
Your radius is not cut at 90 degrees. This causes the edging to track up or down. When you force it to go straight around the corner, this causes the gapping to occur. If you cut your corner with a router and template, these gaps will disappear.

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From contributor K:
I have been laminating 1" radii on 1-1/2" countertops for years without using any other glue than standard spray grade contact cement. The laminate is general purpose and formed at full thickness (the back was not sanded to a thinner dimension). In order for this to work, it requires that the laminate is heated to a state of relaxation that allows for the forming of the material to the core. This is not something that can be done cold. Also, there are some laminate brands that will have a greater chance of cracking because of the physical properties of the sheets. In these situations, I will usually increase to a two inch radii and increase the overhang either on the front edge or end of the core to be certain that the top will cover the cabinet and doors. It is important to make sure that the core, as stated in the previous post, is cut to a true radii, not cut roughly with a jigsaw and/or formed by a belt sander. After cutting the radius, block sand the area of transition where the radius meets the straight edge to remove any slight imperfections. If the area feels rough, it will increase the opportunity to crack the laminate as it is formed around the core. Make sure that the radius is smooth, clean off any excess dust and properly coat with the adhesive.

The best thing to do is learn about how laminate reacts to heat. Purchase a commercial heat gun for about $100 to $125 (we have used Bosch for years, but there are other good brands on the market), and cut some scrap laminate edgebanding to the width that you normally use. We over cut the width by 1/8" of the actual core thickness. Then, using the heat gun, good gloves because the laminate will get hot, and safety glasses, start by heating the strips one at a time and watch the movement of the laminate as it gets hot. Laminate forms at approximately 315 to 325 degrees Fahrenheit. Some shops use a heat-indicating material that is brushed on the edge to indicate the proper temperature; however, once you become proficient with this procedure, you will learn to look for the characteristics that the laminate will exhibit when it "relaxes" and loses its memory from being manufactured. It is easier to observe the relaxation of the material when the edgeband is applied vertically and heated.

Once the material reaches the correct temperature, you need to work quickly to form the laminate to the core edge before it cools. This is when the gloves really help because the piece is hot. After forming the corner, keep moving with the rest of the edge keeping the laminate tight to the core. This will usually eliminate any need to clamp the corner as it cools. Do not hesitate to hold the heat gun on the edgeband too long on the test pieces, and make sure that they have adhesive on them so that you duplicate the actual results when laminating the core. Find out how long it takes a piece of laminate to blister from too much heat and then back off the amount of time the material is heated from your result. The actual process, when performed properly, takes a lot less time than it did to type this response.

Once you learn how to do this correctly, it can make a lot of difference in how you can sell tops to customers, by making the outside corner of any top safer in the traffic areas of the home, by eliminating any sharp corners that someone walks past. It also lessens the dents in your kids' heads as they grow up. And a final benefit is that it removes the dark line and area where the laminate can catch and break. We have all seen the broken corner of a countertop in a kitchen, store or office because the deck was laminated using a standard square edge process.