3.Machining and processing HPL
Corner joints and sheet joints have to be sealed. They must not be weakened by cutouts or notches. The sheets are installed using mechanical fastening and adhesives. Moisture has to be prevented from entering into the material system, which could lead to swelling. For hygiene reasons, we recommend sealing all open edges of the substrate.
On postforming worktops, corner joints can be created with mitre cuts or profile routing. Suitable metal covers are used for butt joints. Edges have to be cleanly routed and the two boards have to be joined tightly. An exact, level transition from one board surface to the other is achieved by using springs, dowel pins, plastic elements, etc. All machined edges must be coated with a suitable protection (e. g. sealing).
The following connection types have proven successfully:
Board connectors
The sealing compound or the adhesive is applied directly to the board joint. When tightening the board connector nuts, it has to be ensured that the two worktop surfaces are aligned at the same level and that the sealing compound is emitted on all sides. Attention: Excess sealing compound has to be removed immediately without using sharp tools!
1 Board joint before tightening the board connectors
a Spring | b Sealing compound | c Adhesive tape
2 Complete board joint
Tongue and groove
To achieve flush surfaces, the HPL surface is selected as a reference surface for producing the grooves for loose tongues or short tongues. The tongues should have a tight fit. The cut edge of the worktop has to be sealed with a sealing compound, which also acts as an adhesive. The excess sealing material must be removed immediately with suitable means. We recommend pressing the joint horizontally together (e.g. by blocking against the wall) until the sealing compound has cured.
Metal cover profiles
Appropriately shaped metal profiles are suitable for covering a board joint. To a certain extent, they save the need of precise machining, but on the other hand they interrupt the flat, easy-to-clean HPL surface. Before attaching the metal profile, seal all edges – including the postforming edge of the worktop
– with sealing compound or adhesive.
Wall connections
Before sealing towards the wall, it has to be ensured that the worktop – especially for larger, self-supporting sections – is sufficiently supported, as otherwise the sealing joints could be destroyed under load.
Smooth (tiled) walls have to be degreased with solvent, just as the worktops, and coated with a suitable primer. Porous surfaces have to be coated with a film-forming primer. For pretreatment with rimers, the instructions from the sealing compound manufacturer have to be followed closely. It is important that the sealing compound sufficiently overlaps onto the surface of the worktop. This avoids excess moisture from entering into the rear edge joint. Sealing towards the wall also has to be applied for worktops which are extended upwards along the wall.
When installing the worktop, it also has to be ensured that it absolutely does not slope towards the wall. This type of installation would also create excess stored moisture.
