The first coating of steel elements should be applied after proper surface preparation in accordance with DIN EN ISO 12944-4, preferably under best possible conditions to ensure long-term corrosion protection. Best possible requirements for surface preparation and application of the coat exist directly after production of the steel elements/steel structures at the steel construction plant under factory hall conditions (shop conservation). Coating at the plant has several advantages over coating at the construction site so that the entire coating or at least partial coating should preferably be done at the plant.

Advantages:

• Best prerequisites for the cleaning and preparation of the surfaces
• Not subject to weather conditions
• Controllable, defined application conditions (application parameters, temperature, humidity, air circulation) allowing the controlled securing of quality-determining properties such as coat thickness and surface condition
• Good drying and thus finishing conditions
• Good prerequisites for quality inspection
• Use of effective technologies to reduce costs
• Controlled waste disposal and managed environmental stress

The time between factory coating and possible completion at the construction site should not be too long. Intervals contractually agreed on must be observed. The protective system is completed at the construction site after repairing possible transport damages (repair with coating materials of the stipulated system).

Initial coating at the construction site requires much more effort by the application installer to ensure the requirements on surface preparation, application, drying and finishing.

All coatings are subject to ageing and a natural depletion process under the respective climate conditions. The repair measures are chosen based on economic and environmental considerations.

Repair:

Small imperfections – restoring the corrosion protection

Partial restoration:

Restore corrosion protection at corroded areas and apply at least a top coat Use of "Repair primers" as basic coat and subsequent application, e.g. of original system (except for initial priming)

Complete restoration:

The complete restoration of the anti-corrosion protection system of a structure after the complete removal of the old coat and possible corrosion products represents comparable requirements as the initial coating at the construction site. Special consideration must be given in addition to the complete removal of corroded areas.

Complete restoration is chosen in case of:

• Large-area rust creepage of the old coat (e.g. more than 20%).
• Bonding defects
• Blistering to the substrate
• Brittleness of the coating system

novatic coating materials can be processed using the application methods of brushing, rolling and spraying – common and known for the product groups. Various products are delivered already adjusted to the respective application methods; we request following the respective instructions. Our technical bulletins list suitable application methods, specific for the product and with the specific technical parameters. The technical information provided produces optimal high-quality coating.

Our quality assurance system safeguards the delivery of high-quality coating materials which the installer uses to produce the final coating product. Flaws in surface preparation and with the processing of the coating materials necessarily produce coats of lower qualities and must be avoided. This stresses the responsibility of the installer! The following information shall help avoid errors and thus ensure quality.

The requirements, prerequisites, rules and standards to be observed as well as the execution of the coating work are defined in DIN EN ISO 12944 Part 7. The requirements of this standard must be met when performing the coating work. The thickness of the coat essentially affects the duration of protection, provided flawless protective layers were applied. Each coat must therefore be applied according to the definition of the specification and in conformity with the product-specific technical bulletin. Individual values of the dry coating thickness falling below 80% of the nominal thickness are not permitted. In accordance with DIN EN ISO 12944-7 individual values between 80% and 100% of the nominal thickness are permitted, provided that the mean of all measuring results is equal or greater than the nominal thickness of the coat. Reaching the nominal thickness must be ensured and areas with excessive thickness must be avoided. The permissible max. thickness is determined by the definition of DIN EN ISO 12944-7.

The requirements of DIN EN ISO 12944 "Corrosion protection of steel structures through coating systems" must principally be complied with as technical set of rules. Additional specific requirements of the customers must be followed.

DIN EN ISO 12944 Part 4 contains: "Types of surfaces and surface preparation". The necessary prerequisites listed to ensure flawless protective coats with the required protective characteristics must be absolutely realised. Appendix A of DIN EN ISO 12944-4 shows the preparation levels in table form for the primary (complete) surface preparation, appendix B the secondary (partial) surface preparation and appendix C the procedures for the removal of non-homogeneous layers and contaminations. The surface preparation must be ensured in the context with the requirements of the product-specific technical bulletin on the surface. The initial coating of steel surfaces usually requires the surface preparation degree Sa 2.5 (ISO 8501-1). In the area of restoration coating novatic has surface-tolerant coating materials available which can be applied on the surface preparation degree Sa2. The respective information of the product-specific technical bulletins must be followed at any rate. This applies analogous to all other materials and surfaces, such as hot-galvanized steel elements. According to DIN ISO 12944-5 novatic provides the user with various suitable products.

Sandblasted surfaces must be properly cleaned before coating by blowing them off followed by broom-cleaning or other suitable methods.

Components are frequently primed or coated with another partial protection system and then pass through production according to the flow of technology before applying the final paint coat/colour. Based on the respective technology coated surfaces may be contaminated by a variety of products affecting the paint-on properties, bonding, gloss and corrosion protection. Such contamination or soiling must be completely removed before applying additional coats. Because the contamination depends on the respective specific technology specifically acting cleaning agents must be selected. Partial dissolution of the coating to be cleaned should be avoided. Appropriate tests must be done before using a cleaning agent.

Water-dilutable coating materials generally respond more sensitively to inadequately prepared surfaces. Principally, it does not matter whether the surfaces are from steel, aluminium or hot-galvanized. The surface to be coated must be dry, free from dirt, dust and grease. The surfaces must be free from chemical products which may stimulate corrosion and/or are water-soluble thus allowing of undesired chemical reactions and/or osmotic processes with subsequent blistering.