Update on general test methods for paints and varnishes

The TC35 SC9 committee is one of the most important groups for standards in the international Coatings industry. Established 40 years ago it established 172 ISO standards and has 20 currently under development. The committee provided us with an update on the latest developments.

ISO standards
ISO standards are the basis to determine and quantify the quality and properties of coatings for a wide variety of applications. Image source: wladimir1804 - stock.adobe.com

The scope of the ISO technical committee TC 35 “Paints and varnishes” is standardization in the field of paints, varnishes, and related products. Subcommittee SC 9 “General test methods for paints and varnishes” has currently five active working groups and is responsible for test methods related to coatings and coating materials. With 25 participating and 20 observing member countries, SC 9 has a wide range of international participants. Interested parties include federal institutes, national associations, commercial testing laboratories, paint and raw material manufactures, test instrument manufacturers, automotive, transportation, wind energy and other applications. Today TC 35/SC 9 has a record of 172 published ISO standards and 20 ISO standards under development. A full list of published standards can be found on the ISO website.

SC 9 deals with technical and analytical test methods to determine and quantify the quality and properties of paints and varnishes for general applications. This includes test methods, for the influencing factors of the coating process, but also to describe the properties of a coating after application and how environmental stress factors act on the coating.

SC 9 typically meets once a year in conjunction with TC 35 and most of its working groups. The last physical meeting was held in 2019 in Shanghai. Scheduled meetings in 2020 in Pittsburgh (US) and in 2021 Berlin (Germany) had to be cancelled and replaced by virtual meetings due to the pandemic situation. The location of the next meetings (around June 2022) most likely will be Berlin, Germany.

The committee manager of SC 9 is Ms. Anita Attra (BSI). The chairperson is Dr. Florian Feil (Atlas MTT GmbH). If you want to get involved in SC 9 activities, please contact us or your national standardization organization.

Working groups and their activities

WG 16 – Coating Powders

Convenor: Dr. Shoaib Qureshi

WG 16 is currently working on the revision of the 14-part ISO 8130 series of standards on coating powder. Six revised parts have been published since 2019. Another seven are currently under revision. The working group is also working on two additional parts of the series: “Part 15 – Rheology” (NP ballot closed on 4th of May 2021) and “Part 16- Density via liquid displacement in a measuring cylinder (NP ballot closed launched closing on 23rd of June 2021).

WG 29 – Electrochemical Methods

Convenor: Dr. Jörg Vogelsang (Sika Technology AG)

Secretary: Bernd Reinmüller (DIN)

WG 29 focuses on the use of electrochemical methods to determine coating properties. The working group has developed a four-part series on the use of electrochemical impedance spectroscopy (EIS) on coated and uncoated metallic specimens (ISO 16773 parts 1 to 4).

Current projects of WG 29 include the revision of “ISO 17463 Paints and varnishes— Guidelines for the determination of anticorrosive properties of organic coatings by accelerated cyclic electrochemical technique” (DIS status) and two new documents: “ISO/DTR 5602 – Sources of error when using electrochemical impedance spectroscopy for the evaluation of coatings and coating materials” (DTR status) and “ISO/DTS 5604 – Test method for assessment of protection of metal by organic coatings using electrochemical noise measurements”. The working group is currently also working on an international round robin on electrochemical impedance spectroscopy measurement with coated samples instead of dummy cells.

WG 29 has a collaboration with ISO/TC 156, Corrosion of metals and alloys, WG 11, Electrochemical test methods.

WG 30 – Properties prior to and during application and drying

Convenor: Dr. Nicole Borho (Dr. Robert-Murjahn-Institut GmbH)

Secretary: Bernd Reinmüller (DIN)

WG 30 focuses on the coating process and the properties of coating materials prior to application. Important standards of this working group are the 7-part ISO 19403 series on wetting and standards related to the volatile and non-volatile matter content (ISO 3233-1/2/3, ISO 3251, and ISO 22516).

A major project of WG 30 is currently the ISO 3219 series of standards related to rheology. “Part 1: Vocabulary and symbols” and “Part 2: General principles of rotational and oscillatory rheometry” are published. “Part 3: Test procedure and examples”, “Part 4: measurement errors” and “Part 5: Calibration, adjustment, verification” are registered as preliminary work items. The 14-part ISO 22553 series of standards on Electro-deposition coatings will be extended by two more parts, “Part 15: Permeate residue” and “Part 16: Pigment-binder ratio”, which have been accepted as new work items.

WG 31 – Properties after application

Convenor: Dr. Petra Hermann (BASF Coatings GmbH)

Secretary: Bernd Reinmüller (DIN)

WG 31 has the largest working program of all working groups of SC 9. Many standards focus on the determination of the coating properties such as scratch resistance (ISO 1518-1/2), resistance to abrasion (ISO 7784 series), resistance to weathering (ISO 16474 series), resistance to cyclic corrosion (ISO 11997 series), determination of hiding power (ISO 6504 series) and many others. The ISO 4628 series of standards deals with the evaluation of the degradation of coatings, including the assessment of degree of blistering, rusting, cracking, delamination, chalking, flaking and more. The ISO 21227 series focuses on the evaluation of coating defects using optical imaging.

Standards which are currently thoroughly revised are “ISO 16925 Determination of the resistance of coatings to pressure water-jetting” (DIS status) and “ISO 11998 Determination of wet-scrub resistance and cleanability of coatings” (active work item).

WG 32 – Coating materials for wind-turbine rotor blades

Convenor: Dr. Florian Feil (Atlas MTT GmbH)

Secretary: Dr. Benjamin Zirnstein (DIN)

WG 32 is the latest of the working groups of SC 9 and was founded in 2013 and working on technical specifications: “ISO 19392 – Paints and varnishes — Coating systems for wind-turbine rotor blades” series of standards. In their use environment rotor blades are exposed to stresses not commonly observed for static applications and therefore require special test methods. Coatings are required to prevent degradation of the rotor blades, especially the leading edge, and must withstand themselves the effects of the environment.

Parts one to three of the series are published as technical specifications. Part one deals with the minimum requirements and weathering resistance of rotor blade coatings. Parts two and three describe the determination and the evaluation of the resistance to rain erosion using rotating arm (Part 2) or water jet (Part 3). New activated projects currently focus on the measurement of the UV transmittance of protective coatings (Part 5) and the determination and evaluation of ice adhesion. (Part 6). Other topics of interest which might lead to new projects in the future are the determination and evaluation of the resistance to soiling and to hail.

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