3.7.6 Edge finishing for HPL composite elements

The edge finishing material is selected depending on the requirements for appearance, function and usage properties of the finished workpiece edge.

Edges/narrow areas on high-use worktops (e. g. kitchens, canteens, laboratories)
Edges on areas with normal use in residential and commercial areas (e. g. table tops)
Edges on areas with less use in kitchens, bathrooms and sanitary rooms (e.g. storage surfaces)
Edges in damp/wet areas (e.g. changing rooms, window ledges)
Edges in areas with hygiene requirements (e.g. in medical facilities)
Edges with a purely decorative function (e.g. decorative edges)
Edges as coverings without visual/mechanical requirements (e.g. blind edges)

Possible edge materials
Edge materials are available in different structures and delivery forms (e.g. sheets, strips, rolls).

Thermosetting plastic edging can be postformed. If the rear side of the edging is treated with hot melt adhesive, bonding agent or a self-adhesive coating, edging can be processed with simple tools and devices.

HPL edging is made of the same material as the element surface and can offer an identical or contrasting colour and texture. For better adhesion, melamine edging is sanded at the rear or supplied with a special, unsanded rear side without resin.

Polyester edging is manufactured in single-layer or multi-layer versions up to 1 mm thickness. The rear side can be smooth, rough or pre-coated with hot melt adhesive.

Single-layer edging can be placed around lightly rounded narrow element surfaces, even without heat application (soft forming process).
Double-layer edging consists of an impregnated base paper and a painted decorative paper (finish film) which are joined with different binding agents.

Thermoplastic edging made of plastic such as PVC, ABS, PP or PMMA are available in a variety of designs. These are up to 10 mm thick and can have a corresponding treatment on the rear side for adhesion (e. g. primer application).

Solid wood edging can be used for design effects and there are virtually no limits to profiling and processing options.

Primer edging consists of resin-saturated paper sheets, are cured and have no finished surface. A coat of paint or varnish is usually applied after the edging has been applied.

It is also possible, however, to use aluminium edging tape, paint coats, moulded polyurethane edging or premade cover profiles (e.g. made of metal

Edge processing of different substrate materials
Different substrates can be used for manufacturing HPL composite elements. The following instructions have to be observed when coating the respective edges.

It is of the utmost importance that the edges of the substrate are clean and even. Otherwise, uneven surfaces or even incomplete adhesion can result.

All wooden materials with sufficiently solid cut edges are suitable.

For lightweight construction panels, i.e. workpiece edges on porous substrates (e.g. foam boards), the effective adhesion area has to be at least a third of the total edge area, with even distribution of the voids. If the adhesion area is smaller (e. g. honeycomb panels), this can be achieved with a pore-filling primer, foam-filling of the voids, a supporting edge or a frame structure.

No generally applicable statements can be made for mineral and metal substrates due to the large variety of materials. Edges on metal substrates are usually not finished. We recommend always consulting the substrate manufacturer.

Table 10: Suitability of adhesive types for bonding the edging materials

	Dispersion adhesives (1)	Condensation resin adhesives	Solvent adhesives	Reaction adhesives	Hot melt adhesives (2)
HPL edging:
from sheets as per EN 438	*	*	*	*	*(3)
Melamine edging, multi-layer:
melamine both sides, rear side sanded	*	*	*	*	*
melamine on one side, rear side not sanded	*	*	–	*	–
Polyester edging, multi-layered:
with smooth rear side	*	–	–	–	*
with roughened rear side	*	*	*	*
Multi-layer with pre-treated reverse side	*	*	*	*	*
Single-layer edges (made of urea/acrylic resin):
with smooth rear side		*	*	*	*
with rough rear side	*	*	*	*	*
Doubled and primer edging:
made of melamine, polyester, acrylic resin	See edging types above
Thermoplastic edging:
made of PVC, ABS, PP, PMMA	*	–	*	*	*
Solid wood edges:	*	*	*	*	*

(1) For the cold bonding activation process with pre-coating
(2) For polyamide hot melt adhesives, a primer coat with special bonding agent is recommended
(3) If necessary, pre-coating with bonding agent

Edge sealing
In addition to the decorative function, the edges on HPL elements primarily have the function of protecting the substrate against moisture. For this reason, the edge protection has to be attached to the workpiece on all sides. The following list contains a selection of options for edge protection (“E”) and for special designs (“EE”).

Edge protection “E”

HPL edges
Polyester edges
ABS edges
PVC edges
PP edges
Melamine edges

Edge protection “EE”

Special lacquer systems for sealing
Hardwood edging (5 mm), sealed
Plastic edging (e.g. made of HPL compact)
Casting resins
Sealing compounds

The edge materials listed under “E” can be used as edge protection “EE” if the edges of the substrates (e. g. chipboard) were sealed first and the sealing permits bonding of the edges. We recommend consulting the manufacturers of the listed materials as to whether these are suitable for the respective intended use.