Powder coating

Powder coating explained
In principle, powder coating comprises the same main elements as a wet painting system – apart from the fact that many wet painting systems involve the use of solvents. The properties stem from binding agents, curing agents, pigments and a variety of additives. The binding agent is normally epoxy, polyester or a mixture of the two. The coating powder is electrostatically charged and then sprayed onto the product. Its finished consistency is achieved by melting and curing in a special oven at a temperature of 180– 200°C.

Pre-treatment
It is essential to choose the correct pre-treatment in order to assure the durability of the coating applied. To ensure optimal durability, we place great emphasis on prepping the product correctly in a modern, multi-stage dipping facility. We use the most highly acknowledged chemicals on the market. For example, for hot-dip galvanized items, we use zinc manganese phosphate.

This pre-treatment is the key to our powder coating system. Given that no coating can be fully diffusion-proof, the prepping process pacifies the metal surface, thereby inhibiting corrosion.-

Powder application
Following chemical pre-treatment, the objects are dried in an oven and suspended on a conveyor belt. Special guns are used to apply an electrostatic charge to the powder that is then blown across the earthed objects, which – thanks to the potential difference – attract the powder. As the attractive force is spread equally over the entire surface, the powder automatically forms an even coat.

Melting and curing

With the powder evenly applied, the objects pass through the curing oven where the coat melts and then cures to form a hard shell at 180–200°C.

Quality control

When the objects emerge from the curing oven, they are first visually inspected, then measured for film thickness and gloss.

Uses

Powder coating meets the most stringent standards on the market with regard to long-lasting corrosion resistance, chemical resistance and finish. Combined with the proper prepping, powder coating is ideal for hot-dip galvanized goods and aluminium, wherever robust anti-corrosion properties are required along with a decorative finish. The process is typically used for extrusion profiles, ironwork fittings, construction sheeting, stairs and railings, agricultural furnishings, park and street furniture, etc.

We also stock aluminium sheet for coating.

We can cover all relevant sheet dimensions from 1000 x 2000 mm to 1500 x 3000 mm.

We also stock aluminium sheet for sale in the following dimensions: 1 x 1250 x 2500 mm – 1.25 x 1250 x 2500 mm – 1.5 x 1250 x 2500 mm – 1.5 x 1500 x 3000 mm

NOT focuses heavily on optimal quality assurance processes with the emphasis on environmental conditions. We are certified to NS-EN ISO 9001:2015 and 14001:2015 standards.

We perform powder coating of hot-dip galvanized steel in accordance with the NS-EN ISO 12944-2, EN ISO 1461 and NS-EN 13438 standards.

Energy/Climate accounts from 2013.

Our production facility for powder coating is in Kvål, just outside Sandnes in Norway. Our current factory commenced production in 1994, and it remains one of the biggest and most modern facilities in Norway. We also have facilities in Larvik.

TECHNICAL DETAILS

The Sandnes facility

Max. object dimensions

l 8000 mm (7200 mm aluminium) x w 800 mm x h 1500 mm.

Max. weight 800 kg

Chemical pre-treatment, aluminium:

13 baths – w 0.8 m x h 1.50 m x l 7.35 m

Drying at 80°C

Chemical pre-treatment, steel/hot-dip galvanized steel:

13 baths – w 1.2 m x h 1.50 m x l 8.85 m

Drying at 80°C

Extractor removes fumes before powder coating at 200°C

Length, curing oven: 48 m

In order to achieve the desired level of corrosion proofing, we operate two separate chemical pre-treatment lines. One consists of two different prepping processes: gold chromate to pacify aluminium, and a non-chrome alternative. The other pre-treatment line uses zinc manganese phosphate for hot-dip galvanized steel and carbon steel. These are the three processes that provide the best corrosion protection available today.

The Larvik facility

Max. object dimensions, Line A:

w 1.0 m x h 1.8 m x l 7.8 m – max. 800–1200 kg/unit

Max. object dimensions, Line

B: w 1.5 m x h 2.2 m x l 4 m – max. 300 kg/unit

Chemical pre-treatment, aluminium: w 1.1 m x h 1.8 m x l 7.8 m

Chemical pre-treatment, steel/hot-dip galvanized steel w 1.1 m x h 1.8 m x l 7.8 m

Length, curing oven: 46 m

In order to achieve the desired level of corrosion proofing, the factory operates three different prepping processes, two of which are gold chromate and SurTec for aluminium. The third features zinc manganese phosphate for hot-dip galvanized steel and carbon steel. These are the three processes that provide the best corrosion protection available today.

Technical requirements, aluminium
The surfaces must always be clean, free from paint chips, white rust (aluminium oxide) and adhesive residue from packing tape, for example.

Anodized objects should be discarded in favour of untreated ones.

The objects for coating must not have been in contact with silicone or substances containing silicone – nozzle lubricants for CO2 welding, for instance, or silicone residue on hands after grouting work. Silicone and silicone gas cause craters in the coating surface. Only lubricants labelled “silicone free” may therefore be used to lubricate production machinery.

Items showing white rust (aluminium oxide) in such large volumes that it causes pitting corrosion in the surface will be considered to be excluded from the warranty arrangement.

Draining: structures involving pipes and other closed and semi-closed components must be sufficiently drained. This means that there must be drain holes and other openings that allow fluid from the pre-treatment baths to flow freely from the objects when they are hoisted up from the baths. If you have any doubts in this regard, please contact us before production commences.

Components must not be assembled before coating. Adjacent surfaces have a capillary effect in the pre-treatment baths. Fluid that enters this intermediate space exits from the opening like steam from a kettle when the coating is cured at 180–200°C. This steam will ruin the coated surface in the area around the blow hole.

Requirements on orders
You must state in advance the corrosion class in which the objects will be exposed. The different operational environments are divided into corrosion classes, from class C1 (dry, indoors) to class C5 (aggressive industrial environment/outdoor coastal climate). Protection for the current corrosion classes is achieved through the choice of metal, pre-treatment and top coating.

Only polyester coating is to be used for outdoor environments. Epoxy can be used for indoor environments (i.e. settings not exposed to direct sunlight).
All orders must be accompanied by correctly dimensioned drawings/sketches and statement of the relevant coating surface. Along with the drawings/sketches, you must clearly state where the objects are to be fitted (for example, east-, west-, north-, south-facing façade, building, project, etc.).
Adhesion warranty must always be agreed in advance through a specific offer/project.
Sheeting that is bent after coating is not covered by the warranty.
Description of powder coating of hot-dip galvanised steel.

Steel is an excellent material for use in architecture, largely on account of its strength, mouldability and welding options. For generations, hot-dipped galvanising has consistently proved its incredible capacity to protect steel against corrosion.

In recent years, systems have been developed for powder coating hot-dip galvanised steel that satisfy the stringent demands on adhesion to the zinc coating, combined with a superior surface finish. Given that hot-dip galvanising in and of itself is a relatively “coarse” surface treatment, some demands must be made on the steel quality if the product is to achieve the desired corrosion class and surface finish.

The steel quality and finish of the final product must always be agreed in advance.

Suitable steel quality
Steel that is unsealed or aluminium sealed – ideally with a silica content of less than 0.02% – is always required for the best possible finish (NOT Pulverlakk AS finish class 1).

This steel will also produce a shiny, homogeneous surface.

Steel with a silica content of 0.15–0.20% can be used for finish class 2.
It can be useful to select different finish qualities. For example, not all parts of a railing need the same finish class, with the best finish being reserved for the hand rail. This helps with cost optimisation of the product.

By arrangement, NOT Pulverlakk AS can provide a 15-year warranty against peeling, and a classification of the surface finish included in ZiPoCoat (hot-dip galvanizing + powder coating).

These are all measures we apply to ensure we are able to deliver a quality product that matches the customer’s expectations.

Warranty
By arrangement, NOT Pulverlakk AS can provide a 15-year warranty against peeling, and a classification of the surface finish included in the NOT-PROCESSES® (hot-dip galvanizing + zinc manganese phosphate + power coating).
These are all measures we apply to ensure we are able to deliver a quality product that matches the customer’s expectations.

The warranty applies to adhesion of the powder coat to the base material.

The warranty is based on many years of experience and development, which gives us full confidence in our procedures. As such, the warranty applies up to and including corrosion class C5 in accordance with NS EN ISO 12944-2:1998.

The warranty is based on the use of the best pre-treatment chemicals and skills, combined with the best powder qualities available on the market.

The warranty covers coating of aluminium and hot-dip galvanized steel.

For coating hot-dip galvanized steel, it is essential that steel of the correct quality are used (cf. technical requirements for the NOT-PROCESSES) and that both the hot-dip galvanizing and powder coating are performed by companies within the Norsk Overflate Teknikk AS (NOT) Group.

Powder-coated surfaces must be washed as soon as possible, and no later than three (3) months after installation. Maintenance of the surface is limited to simple washing with mild soapy water. The frequency of the cleaning depends on the environment in which the products are used, and the requirements on their appearance. We recommend cleaning before any pollutants penetrate the surface, but we consider an annual wash to be an absolute minimum – irrespective of the environment in which the products are used. In marine environments (splash zone/shoreline) and areas with heavy industrial pollution, we recommend cleaning more frequently.

We will repair any defects that result in the powder coat peeling on site. By arrangement, we will cover the cost of the coating material, labour and travel expenses necessary to repair any defects.