Search INDUSTRIAL LAB
Call INDUSTRIAL LAB+49 2762 9740-0
Email to INDUSTRIAL LABSend an email
INDUSTRIAL LAB at LinkedInLinkedIn-Profil
Image ProspektBrochure
INDUSTRIAL LAB inquiryDirect inquiry
Surfaces & Coatings-ANALYTICS IN THE AREA

Salt spray test according to ISO 9227: Protection by coating

Salt spray test (old - DIN 50021)- for parts and components

Components are coated for different reasons. A general distinction is made between two types of coating - the functional, technical coating and the decorative coating. In the technical area, the purpose of the coating is to protect the substrate from corrosion.

The focus of the coating is therefore on the function. The situation is different with decorative coatings. Here, the look has to be right - glossy surfaces, colour effects, perfect haptics. All of this should underscore the value of the product and look good for as long as possible.

Salt spray test and alternating corrosion test ...Two applications with the same goal - corrosion is unwanted. 

 

Bild-Salzsprühnebel-Korrosionswechseltests

Corrosion test

Coated components are subjected to very different stresses in their daily use. While metallic coatings react sensitively to the chloride in the test solution of the salt spray test, organic coatings are more likely to be impressed by moist heat. The requirements for technical coatings are also different to those for decorative coatings. We have a suitable test for every stress, which puts the component through its paces to ensure that there are no problems in later use:

  • Salt spray test

  • Alternating corrosion test

  • CASS test

  • ESS / AASS test

Salt spray test (NSS) according to ISO 9227

neutral, the classic

The neutral salt spray test or salt spray test is the classic test for all situations. Everyone knows it as the salt spray test, NSS or salt fog test and it forms the basis of many corrosion methods. Metallic components do not like the chloride from the salt solution at all and react with typical corrosion patterns depending on the quality and type of coating or substrate. The neutral salt spray test is ideal for comparative testing. In most cases, a statement on the general condition of the components and their suitability for the application is obtained within a short time.

  • Metallic substrates with organic layers

  • Metallic substrates with metallic layers

  • Plastic substrates with metallic layers

  • Components for offshore use

Bild-Neutraler-Salzspruehnebeltest-NSS-

Alternating corrosion test

the realistic one

Due to the ever-increasing requirements placed on components, the coatings have become increasingly high-quality - alloy coatings, zinc flake coating, flake coatings and complex coating systems with multiple nickel layers. Demanding coatings require demanding tests.

In the alternating corrosion test, the effective stress in the later life of the component is simulated. In the salt spray phase, the components are exposed to the salt solution, which wets the surfaces and crystallises in the subsequent warm-dry phase. The salt is then ‘activated’ again in the warm-wet phase and works on the surface of the components. These cycles of different stress are repeated continuously.

The alternating corrosion test provides realistic corrosion patterns and progressions and can be used to test components with pinpoint accuracy depending on the installation situation.

  • Metallic substrates with organic layers

  • - Metallic substrates with metallic layers

  • - Plastic substrates with metallic layers

Bild-Korrosionswechseltest-Analytik

CASS test

the Aggressive

The acronym CASS stands for copper accelerated acetic acid salt spray test. In addition to the original salt solution, acetic acid and copper ions in the form of copper II chloride are added to the solution. The acetic acid pulls the pH value from neutral into the slightly acidic range and the copper ion acts as a catalyser. An additional complicating factor for the test specimens is that the test is carried out at an increased temperature of 50 °C. These are all factors that really affect the test specimens. The aim here is not to see what might happen to the component later in life - the aim here is to quickly and efficiently detect weak points in the substrate and / or the coating.

  • Painted aluminium substrates

  • Plastic substrates with copper-nickel-chrome coating

  • Zinc diecasting with copper-nickel-chrome coating

Bild-CASS-Test

Salt spray test ESS / AASS

not only for sanitary parts

In the ESS or AASS (acetic acid salt spray test), the pH value of the salt solution is adjusted to the weakly acidic range. This and the added acetate anion place additional stress on the test specimens. While the acetic acid salt spray test was initially used primarily for components from the sanitary sector to take into account the use of acetic acid cleaners, it is now also being used in the automotive, printing cylinders and cutlery sectors. Nickel coatings or stainless steels with nickel as an alloying element can react sensitively to the acetate anion.

  • Components from the sanitary sector

  • Piston rods, printing cylinders

  • Zinc die casting with copper - nickel - chrome coating

Bild-ESS-AASS-essigsaurer Salzsprühnebeltest

Your contacts for Salt spray & corrosion change tests

For enquiries about these analyses, please contact our laboratory team at anfrage@industrial-lab.de or get in touch with your contact person:

Timur Gök

Timur Gök

Head of Team Corrosion
 0212 22147 - 5
 Send e-mail

Julia Krüger

Julia Krüger

Electroplating technician
 0212 2214 - 75
 Send e-mail

Sandy John

Sandy John

Head of Laboratory
 0212 22147 - 0
 Send e-mail

Frequently asked questions about the salt spray test

Which salt for salt spray test?

In the salt spray test, we spray a 5% sodium chloride (NaCl) solution. Sodium chloride (NaCl) is commonly known as table salt. However, you should avoid using common household salt as far as possible, as other ionic components such as fluoride are sometimes added and it often contains anti-caking agents. We use sodium chloride with a purity of at least 99.5%, which we buy with a certificate from specialist retailers. We completely dissolve 50 g of sodium chloride per liter of test solution. This is important so that small crystals do not clog the hoses or block the fine spray nozzle.

Which coating is tested in the salt spray test?

Traditionally, metallic coatings are tested in the salt spray test. However, organic coatings such as powder or dip coatings as well as CDP on steel or other metallic substrates are also tested in the salt spray test. Here, the quality of the coating process is tested by applying a defined scratch mark through the coating onto the substrate.

We test technical coatings on components with hard chrome, electroless nickel, zinc or zinc alloy coatings (zinc-nickel, zinc-iron), zinc flake, hot-dip galvanized and various paints as well as passivations or conversion coatings, such as anodizing. We also test decorative coatings and coating systems on fittings and decorative parts, such as copper - nickel - chrome or PVD coatings in the salt spray test. The applications are diverse, but a metallic component must be present - either the substrate or the coating

What do you do with a salt spray test?

A salt spray test, also known as a salt spray test, is a standardized procedure for evaluating the corrosion resistance of materials and coatings. Here are the main steps:

  1. Preparation of the samples: The workpieces to be tested are cleaned and placed in a special test chamber.

  2. Generation of the salt fog: A 5% sodium chloride solution (saline solution) is sprayed in the chamber to create a corrosive atmosphere.

  3. Test conditions: The chamber is maintained at a constant temperature of approximately 35°C and the salt solution is sprayed continuously.

  4. Test duration: The duration of the test can vary from a few hours to several thousand hours, depending on the requirements of the test.

  5. Evaluation of the results: At the end of the test, the samples are examined for signs of corrosion such as rust, blistering and infiltration of the coating.

The salt spray test is often used in the automotive, construction and mechanical engineering industries to check the quality and durability of coatings and materials.