Selected Answers

From Per Gabrielsson of Free Lance Consultations and Inspections on March 8, 2013:
     Eric, your recommendation ...read more      Eric, your recommendation of performing the test with a solvent recommended by the manufacturer (in many cases, the IOZ thinner) does not give you a correct result of hydrolysing and is not in compliance with the ASTM MEK (methylethylketone) test.

From Raymond Merrill of Texas Department of Transportation on February 26, 2013:
     An IOZ coating failing th ...read more      An IOZ coating failing the MEK rub test is an indication that the coating is not fully cured (cured, as opposed to dried - there is a difference). IOZs, in my experience, dry relatively quickly. Curing, however, can take anywhere from 24 hours to 7 days, depending on ambient conditions. Should it fail the MEK rub test, spray with water spray and try again. Consult the Product Data Sheet to determine about how long it should take to completely cure.

From Giuseppe Santagata of NACE Certif. Coat. Insp. level III # 2737 on March 5, 2013:
     Normally, IOZ is applied ...read more      Normally, IOZ is applied when RH is more than 50%; otherwise, it is a good practice to spray nebulised tap water over the coated substrate. (The coating manufacturer shall indicate in its technical data sheet after how many hours it is possible to spray water on the surface, which depends on  the RH level, the air temperature, steel temperature. etc. during the IOZ application normally, at least  2 hours after the application in my experience.)
     Another technique for small surfaces is to put  wet rags over them  and wet them periodically until IOZ passes the MEK test (i.e., 50 double rubs).

From Ahmed Abd Ellatif of MOPCO on February 25, 2013:
     Leave it to dry for one d ...read more      Leave it to dry for one day and repeat the test. If it fail again, reblast and repaint. 

From Alan Brown of AB INDEPENDENT INSPECTION SERVICES on March 11, 2013:
     Like my old friend Per Ga ...read more      Like my old friend Per Gabrielsson says, if after one week the IOZ has not cured, reblast & recoat under the correct conditions specified. It's  the only way to go. Personally, I have had past experience with this and have done this this after 4-5 days !!

From Carl Havemann of www.corrosioneducation.co.za on March 8, 2013:
     I have used the following ...read more      I have used the following method with success but recommend that more lab tests are done to verify its success. Apply a waterbased acrylic primer 'tie coat' (50micron) to the uncured IOZ. The water thus retained in the IOZ layer promotes cure(hydrolysis) with time. The acrylic primer can be overcoated after 12hrs(?) with any top coat,  i.e., alkyds, epoxy etc.

From Per Gabrielsson of Free Lance Consultations and Inspections on February 26, 2013:
     If  the IOZ is faili ...read more      If  the IOZ is failing 1 week after application, reblast and recoat.

From Chin Hong Leow of GALE Engineering on March 4, 2013:
     The method of inspection, ...read more      The method of inspection, reference code or standard, and acceptance criteria shall be clearly described in the contractor Painting Procedure, which shall be reviewed and approved by the client before production painting work is allowed to commences. Before over-coating, it shall be checked, with the solvent recommended by the manufacturer, that the hydrolysis is complete by soaking the surface with a rag impregnated with the recommended solvent and in accordance to ASTM D 4752 MEK Test on Inorganic Zinc Ethyl Silicate. If hydrolysis is not complete, the inorganic zinc ethyl silicate shall be removed by blast cleaning and re-painted. In the case of localised or isolated repair due to welding or damaged coating to the bare substrate, zinc ethyl silicate primer shall not be used for touch up repairs. Zinc rich, 2-components epoxy primer should be used instead.

From richard d souza of stoncor middle east llc on February 25, 2013:
     Raise the relative humidi ...read more      Raise the relative humidity by steam or water spray to hydrolyse the ethyl silicate binder completely. Repeat the MEK rub test and the process till it passes.