CASS Test — Copper-Accelerated Acetic Acid Salt Spray (Fog) Test — (ASTM B368, B117)

Touchstone has several salt spray cabinets, and can perform both standard and customer-specified testing to ASTM B117, ASTM B368, ASTM G85 and other specifications. Touchstone has laboratory tested both coupons and entire components for automotive, aerospace, and other industries.

For a PROMPT response and quotation contact us at info@trl.com or tel 304-547-5800.

ASTM B368 is a cyclic corrosion test that uses a solution of sodium chloride and ammonium sulfate which is much more dilute than traditional salt fog (spray). Also known as the CASS test, this test is commonly used to evaluate paints on steel as well as to determine corrosion resistance of various aluminum alloys. It is also used for testing chromium plating on zinc and steel die castings. It was developed specifically for testing decorative electrodeposited coatings of nickel/chromium and copper/nickel/chromium. Uses include research and development, specification acceptance, manufacturing control of product or process, and simulated service evaluations.

Salt Solution: A standard ASTM B117 salt solution of 5 parts (by weight) of salt to 95 parts water is prepared. Reagent grade copper chloride dihydrate is then added at a rate of 1 gram to 4 litres of salt solution. Fog is collected and tested, and the salt-copper solution is adjusted to a pH of 3.1 to 3.3 by adding reagent grade glacial acetic acid.

pH Range: 3.1 to 3.3

Test Temperatures: The exposure zone is to be kept at 49 +/- 1°C.

Test Cycle: ASTM B368 (CASS) is a continuous spray (fog) test.

Test Background: The ASTM B368 (CASS) test method is used to determine corrosion resistance of various aluminum alloys. It is also used for testing chromium plating on zinc and steel die castings. It was developed specifically for testing decorative electrodeposited coatings of nickel/chromium and copper/nickel/chromium. Uses include research and development, specification acceptance, manufacturing control of product or process, and simulated service evaluations.

Sample preparation and placement: The cut edges of samples that are multilayered, coated, or plated are coated so as to not cause edge corrosion. When ready for the test cabinet, metallic and metallic coated samples are cleaned with an appropriate cleaning or solvent solution. Organic and other samples with nonmetallic coatings are not cleaned.

Test time and inspections: Test time ranges from 24 to thousands of hours, usually in 24 hour increments. Typical exposure lengths in hours are: 6, 12, 22, 48, 96, 192, 240, 504, and 720. One option is to use multiple panels/samples, pulling one set out at every specified time period. Another option is to evaluate/photograph the panels/samples at each specified interval, and return them to the test cabinet for the total test time.

We can recommend a test length, and also an inspection frequency. Consulting on corrosion problems is also available. Our light microscopy, metallography, and mechanical testing laboratories can provide a full suite of tests to support your material characterization program.