Letter 3451

Alternative to Ferroxyl testing & Spot Indicator of Chromium and/or Nickel  

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I am trying to find a porosity indicator for Electroless Nickel type coatings on steel that *does not* contain potassium ferrocyanide (Ferroxyl Test). Is there any other indicator that indicates presence of iron?

I have also seen references to submerging in boiling water. Has anyone had experiences pro or con these two methods?

Also, is there anything to detect presence of hard chromium or nickel on a steel surface as a *color indicator* spot test (recognition by the appearance alone is difficult on some exotic materials) I would prefer to not use droplets of HCl and looking for gassing or discoloration.

H. Sencza
- Canada

The copper sulfate spot test may be a useful alternative to the ferroxyl test. This test plates out copper on to expose iron surfaces. The holiday size resolution for a copper spot, however, may not be as good as for the bright blue indication in the ferroxyl test. The method is used often for checking for free iron contamination on stainless steel as a test for passivation. As for a spot test to check for plating, investigate the spot test kits provided by Koslow. They will probably have something that would be easy, safe, and reliable.

Larry Hanke materials testing laboratory Minneapolis, Minnesota

I am looking for a non-toxic alternative to ferroxyl solution for testing stainless steel which has been passivated.

Kenneth Fortune
distiller - Scotland

Probably the simplest "non-toxic" test is the boiling distilled water test. There are a number of varieties of this. You can see ASTM F 1089 for a typical test. Different industries use different times on the test. Very typical is 1 hour in boiling water, 1 hour cooldown, 1 hour in air to dry. Many varieties of this.

Lee Kremer Stellar Solutions, Inc. Algonquin, IL, USA

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