Frequently Asked Questions about Arpa HPL

Below are some of the frequently asked questions we receive on a daily basis. If you have any further questions please send us a quick note. Click here.

Production of Arpa

How is a sheet of high-pressure laminate (HPL) made?
HPL laminates consist of superimposed layers of paper, impregnated with thermosetting resins and permanently bonded together by siimultaneously applying heat (greater than 120° C) and pressure (greater than 5 MPa) for periods of 40 / 50 minutes.
What are the poperties of HPL in general?
Its main mechanical, physical and chemical characteristics are:
  • Impact resistance
  • Scratch resistance
  • Lightfastness
  • Ease of cleaning
  • Heat resistance (occasional, up to 180° C)
  • Hygiene
  • Suitability for contact with food
Do the levels of heat and pressure the materials are subjected to in the presses affect the properties of the finished product? If so, how and to what extent?

The quality of HPL laminates is influenced by the levels of heat and pressure applied during manufacture. Arpa employs a pressure greater than 7 MPa and a temperature of about 150° C. The surface and structural qualities of hte laminates achieve a high standard as a result.
What is HPL made of?
It consists of about 60-70% paper and about 30-40% thermosetting resins. The latter are of two different types; the inner layers of paper are impregnated with phenolic resin and the outer layers with melamine.
What makes a low-quality HPL different from an excellent one?
Poor resistance to scratching, impact, wear, steam, heat, stains and light are indicative of poor quality raw materials and/or manufacturing processes employing lower pressures or temperatures and shorter heating times. The minimum performance requirements are set out in EN 438.

Characteristics of HPL

Do laminates follow the CE marking rules for construction products?
Only laminates 2mm or more thick used in the construction industry (e.g. walls) must conform to the rules for CE marking. For all other applications, such as furniture, this specific marking is not required.
What international standards does HPL meet?
There are two international standards, both of a voluntary nature, European Standard EN 438 (European HPL regulations) and ISO 4586. These set out the minimum requirements and the performance characteristics for each type of HPL. EN 438 is the most complete and recent standard as it considers not only the more traditional types of laminate but also the more aesthetically and technically advanced varieties.
Which of the existing standards is commonly used?
The 2004 revision of international standard ISO 4586 in two parts, one dealing with the specifications and the second with test methods, takes a standpoint aimed at a global market but has now become obsolete. The European EN 438 standard is more up to date and has 9 parts. The first part is a guide while the second covers test methods. Parts 3, 4, 5, 6, 8 and 9 deal with the different applications. Part 7, which is mandatory as regards compliance with European Regulations for Construction Products, covers the requirements for CE marking.
Can different finishes affect the properties of the finished product?
Yes. For example, a glossy finish will be less scratch resistant than a more textured one. For more detailed information, it is always advisable to refer to the specific Product Data Sheet for each laminate.
What performance standards does EN 438 require?
EN 438 consists of 9 parts but only one of these sets requirements. Part 7, in fact, deals with the essential requirements specified in the terms of reference of the European Commission Regulations on construction products, M/121 (interior and exterior wall and ceiling finishes) and M/113 (wood based panels). Parts 3, 4, 5, 6, 8 and 9 of the EN 438 Standard each apply to specific types of laminate and give recommendations for areas of application, laminate performance standards and test methods. We recommend reading these parts carefully for detailed technical information.
What temperatures can HPL withstand without deterioration or discoloration?
HPL can withsand up to 180° C without deterioration or discoloration. However, thsi relates to an accidental rather than a regular occurrence in that prolonged and localised heat can cause loss of brightness in the decor color as well as yellowing and surface blistering. In the kitchen, care should be taken to avoid direct contact with saucepans just taken off the cooker; the bottom of a pan containing hot oil can reach 250° C.
In terms of resistance to heat, moisture, scratching, impact etc. does each type of HPL have specific properties?
Every HPL can claim exceptional hardness and resistance to scratching, impact, abrasion, chemicals and heat. Each type can have very different characteristics; however, in line with the required performance perfomance for the specific application. European standard EN 438 classifies HPL into different grades according to its properties and application: Standard (S); postforming (P); suitable for horizontal (H) or vertical (V) applications, flame retardant (F); compact (C) or external (E), pearlescent (A), metal (M) or wood veneer finishes (W), multicolor core (B) and metal reinforced. For example, laminates for horizontal applications have more resistant surfaces than those for vertical applications, the physical and mechanical properties of thick laminates are greater than those for thin ones, postforming laminates can be hot formed and flame retardant laminates have increased fire ratings.
What is meant by antibacterial HPL?
In general, all HPL is inherently hygenic due to the density of its surface and its ease of cleaning. ARPA's Silverlam HPL has a special innovative structure providing anti-bacterial protection. This is mocrobiologically tested and uses silver ions to inhibit bacterial growth and reduce the quantity of bacteria by 99%.
Where there are special peformance requirements for specific applications, can Arpa provide specific product details?

Reaction to Fire

In construction, if there are national regulations and markings as well as the European ones, what is Arpa's approach?

Arpa products are supplied with European cerfitication. Customers should check the local requirements. In the case of national markings such as the French CSTBat or the Dutch Komo, Arpa conforms to the local market.
As regards to reaction to fire, to which classification in American regulations do Arpa's flame retardant laminates belong... and what about the standard grade?

One of the most important test for the North American construction industry is the ASTM E 84 (Tunnel test). Arpa's flame retardant Integrale laminates achieve class A, which is the highest, while the standard grade achieves class B.
How does the manufacture of Flame Retardant HPL differ from that of the standard grade?
Laminates are organic materials which, by their very nature, even in the standard grade, do not burn very well or rather, do not ignite easily when exposed to flames and contribute relatively little in the event of a full scale fire. There are also flame retardant HPL laminates which, unlike the standard ones, are manufactured with special additives that make them particularly flame resistant. They are used in the construction and transport industries where there are legal requirements or safety regulations. The additives are halogen free.
For fire doors should I use flame retardant HPL or can I use the standard grade?
Fire resistance is the ability to retain load bearing capacity (R), integrity (E) and insulation (I) properties for a defined period of time. In the construction of buildings, this is assessed for finished elements with structural functions (e.g. doors or walls) in which the HPL laminates are just one component. For fire doors, it is essential to use a structure with the required REI properties such REI 30 or REI 60 (where the numbers indicate the minutes for which the element retains these properties). If the substrate possesses the correct fire resistance properties and the adhesive is suitable, it is also possible to use the standard grade of HPL. It will be up to the door manufacturer to experiment to find the best solution.
What is the difference between reaction to fire and fire resistance?
Reaction to fire refers to the tests carried out on an individual material, in our case HPL. Fire resistance, however, is measured by tests on the finished article, i.e. the composite panel formed of HPL, the substrate on which the laminate itself is applied, the bonding or fixing system and any supporting structure. Typical examples of this latter type are the doors or ventilated cladding for building façades.
Does postforming HPL meet the requirements of the shipbuilding industry, including fire resistance?
Yes. The HGP grade (Horizontal General Purpose Postforming), if combined with a fire-retardant substrate, meets all the requirements of the IMO-MED shipbuilding regulations as regards fire resistance and heat release properties.


Is HPL a chemical product?
No. It is not a chemical substance but a thermosetting plastic material whose physical and chemical characteristics are completely different from those of the raw materials it is made from. During the high-pressure process, the resins that the sheets are originally impregnated with undergo an irreversible reaction, producing a stable and non-reactive material.
Is it true that HPL does not release formaldehyde?
The formaldehyde emission of Arpa's HPL does not exceed 0.03 ppm with the EN 717-1 chamber method and 0.4 mg/m2/h with the EN 717-2 gas analysis method. This level is far below the minimum required in Europe for wood based panels used in furniture. In addition, given its very low permeability, when HPL is combined with a wood-based panel, it acts as a barrier against possible formaldehyde emissions from the substrate itself.
What is the average life of a sheet of HPL?
The life expectancy of HPL laminates is much longer than that of a human being! A piece of furniture finished in HPL is not easily damaged. Of course, the actual lifespan depends on how it is used, especially as regards the decorative surface. In any case, its durability is another of its considerable qualities and helps to make it especially attractive from an environmental point of view as well. Long life means less waste and a saving in resources.
How can HPL be disposed of?
HPL is not a dangerous product and requires no special treatment. Thanks to its high cellulose content, the laminate can be used for energy recovery at the end of its life cycle, in incinerators authorised for municipal waste. In the factory, waste materials are used as fuel to generate the energy needed for manufacturing. The residual ash can be treated as solid municipal waste (EAK Code 120105).

Hygiene and Maintenance

Is it possible to use any cleaning product or are there products to be avoided?
Almost all normal household cleaning products or disinfectants are tolerated perfectly well, as long as they are not abrasive or strongly acidic or alkaline. Bleaches or heavily chlorinated products should also be avoided. After cleaning with detergent, rinsing and thorough drying is advisable, to prevent stains. It is not necessary to use furniture polish or wax based cleaners to maintain the surface sheen and indeed, these eventually form deposits on the surface that absorb dust and dirt.
As regards surface stains, to which substances is HPL resistant and which are the ones to avoid?
HPL has a good resistance to most substances that can cause stains, including syrups, fruit juices, jams, liqueurs, milk, tea, coffee, wine, soap, ink, citric acid and acetone. It is as well, however, to remove products such as cranberry or beetroot juice, concentrated tomato or fruit juices, caramel and some very strong sanitary bleaches as soon as possible.
Is it true that HPL is especially hygienic?
Yes, absolutely. An HPL surface is unfavourable terrain for the growth of germs and is therefore a material ideally suited to all situations that require maximum hygiene, from kitchens to operating theatres.
How is HPL cleaned?
A simple cloth dampened with hot water is almost always sufficient, because the surfaces of HPL are compact, not very porous and are resistant to the stains and chemicals commonly used in a domestic environment. Of course the less textured finishes can be cleaned more easily.


What precautions are recommended for application intended for dry or wet environments?
The success of applications intended for particularly dry or wet environments depends essentially on the choice of substrate and proper pre-conditioning of the materials. Where there are variations in humidity it is essential that the panel is symmetrical on both sides and that the humidity conditions are as similar as possible for both faces. Bear in mind that, as regards dimensional changes due to wet conditions, the laminate is similar to wood, so products need to be designed using appropriate adhesives, leaving adequate moisture escape routes and making screw holes a little larger.
ARe there recommended and/or finishes for particular applications?
The choice of pattern and/or finish is important both from an aesthetic and functional aspect. There are big differences, for example, between a worktop potentially subject to heavy wear and tear, a small vertical door of a little used piece of furniture and a building façade subjected to the weather, heat and sunlight! In general we can say that surfaces with more textured surface finishes and lighter colours offer better performance in terms of scratch resistance and abrasion than dark and glossy ones. Equally, smooth surfaces or those with a fine texture are easier to clean than those that are heavily and deeply textured.
Can the laminate be applied directly to the walls that are to be clad?
Absolutely not if they are functioning, plastered or painted walls, for many reasons: because of the natural surface irregularities that do not allow good adhesion, because of the moisture released from the bare wall, because adhesives do not perform well when hand-applied to plaster and because the dimensional movement of HPL, which differs from that of the wall, would create stresses and possible cracking. To prevent the laminate warping, it is good practice and an indispensable rule "to let it breathe", isolating it from possible sources of moisture. In conclusion, the laminate must be applied to a framework or support that is then fixed to the wall.
Can HPL be used for signage?
Yes. Digital technology makes it possible to incorporate any kind of sign or wording, with perfect results.


Can I make internal cuts without risk of the panels splitting or cracking?
Yes. Rounded corners need to be formed (5mm radius) and 90° angles avoided at all costs. Care should be taken, when forming notches and holes, not to induce micro cracks that could degenerate into real splits in the long term. In addition, the composite panel must have been manufactured with rigid or semi-rigid adhesives and, of course, with suitably pre-conditioned materials.
What should be done to make sure the composit panels do not warp?
To counterbalance the effects of possible variations in material sizes, it is almost always necessary to apply a sheet of laminate to the back of composite panels, as similar as possible to the one on the front, (preferably of the same thickness, from the same manufacturer and cut in the same direction). In addition, simultaneous pre-conditioning of the substrate, the laminate and the balancing sheet is essential prior to bonding.
Can metallic laminates be worked and bent like the others?
Metallic laminates require special attention but they can be worked with the normal equipment used for all laminates. Metallic laminates are also available for postforming. For detailed information on these processes, Customers can refer to Arpa's technical documentation.
What are the most suitable substrates for HPL?
Plywood, particle board and MDF are all particularly suitable because, like the laminates, they are cellulose based and therefore have similar dimensional movement. In some industries and applications they require special substrates such as mineral fibre boards, sheet metal, foam or honeycomb panels etc. These materials all require special bonding and manufacturing techniques.
What substrates can be used for metallic laminates?
Compared to other high-pressure laminates, metallic ones require greater care in the choice of substrate and adhesive. To achieve good results, the substrates should be perfectly smooth and the surfaces free from any undulation or blemish. Various adhesives (other than those that are urea based) can be used but the best results are obtained with a very evenly spread PVA type adhesive (which has no tendency to shrink) because this minimises the risk of irregularities extending over the finished surface.
Can the laminate be bent?
When the laminate needs to be bent, the "postforming" grade should be chosen (either HGP or VGP); this retains all the properties of HPL but is also capable of being hot formed into either concave or convex shapes. For detailed information customers can refer to Arpa's technical documentation.
What alternatives are there for finishing hte edges of a worktop?
There are several options:
  • Using postforming HPL and bending it, as the design requires
  • Bonding a strip to the edge, of the same HPL as used for the surface
  • With PVC, bonding a strip to the edge
  • With wood, gluing a strip to the edge of the composite panel

Storage & Transport

Are there any special precautions for the storage of HPL?
The panels should always be placed on flat, horizontal shelves, in pairs, with the decorative sides facing inwards. They should be well protected from dust and, in the case of laminates of limited thickness, from accidental stresses that may mark the surface. If horizontal storage is not possible, they can be placed in slightly inclined (60 / 70°) vertical stacks with support provided across the entire area of the sheets to keep them flat.
ARe special temperature and humidity conditions required in warehouses?
Decorative laminates should be kept in closed rooms and under normal environmental conditions, approximately at a temperature of between 10 and 36° C and humidity of 60 / 65%.
Can the laminate be transported or stored rolled up?
In general it is better to handle the sheets carefully, keeping them laid flat and using pallets of appropriate size and stability. Only very thin sheets can be transported rolled up, with the decorative face on the inside and in rolls about 600mm in diameter.