ASTM G 85-A5: Standard Practice for Modified Salt Spray (Fog) Testing (Prohesion)
While neutral salt spray (ASTM B 117) is widely used as an accelerated corrosion test, there are many who question its relevance to real world performance. To answer the skeptics, a number of other corrosion tests have been designed, including prohesion testing. The prohesion test differs from the standard salt spray corrosion test in three areas: (1) it uses a weaker electrolyte solution (0.35 % ammonium sulfate and 0.05% sodium chloride rather than 5% sodium chloride; (2) the pH is slightly lower (5.0–5.4, not 6.5–7.2); and (3) the exposure is cyclic, alternating between one hour of spray at room temperature and one hour of bake-off at 35oC. UDRI is accredited by Laboratory Accreditation Bureau (L-A-B) to perform ISO 17025 certified prohesion testing which conforms to ASTM standard G 85-A5.
UDRI has six Q-Fog cabinets in which we perform the test and we take pride in operating the corrosion cabinets in a uniform manner. Our quality control includes checking and recording the following parameters daily (except for holidays and weekends) during the entire time the test is being conducted:
- If samples are scribed, the scribing is done with an engraving machine which produces precise, uniform cuts.
- The fog cycle is maintained between 24oC and 26oC; the dry-off cycle is held between 34oC and 36oC with <30% relative humidity.
- Sample racks are rotated weekly.
Test specimen preparation is done in accordance with the test plan. Panels are often rated after each 504 hours of exposure. Because there are a variety of expectations for the test, the rating scale is chosen before testing begins and is spelled out in the test plan. Before each rating, panels are rinsed with warm tap water and then with deionized water and then dried.
At the conclusion of the test, samples are rated for:
- Corrosion creepage away from the scribe
- Blistering (ASTM D 714)
In addition, samples are photographed if requested.
If you would like a quote on how much it would cost to test your samples, please contact UDRI's Bill Culhane or call 937-255-0955.
Other Corrosion Testing Available:
ASTM B 117: Salt Spray (Fog)
GM 9540P: Accelerated Corrosion
NAS 1534: Filiform Corrosion