Problem Solving Forum
November 6 - November 10, 2017
What are the pros and cons of using an organic vs. inorganic zinc primer?
Marco Fabio Ramenzoni of ZINGA METALL BRASIL on
November 10, 2017:
Let me agree 100% with my dear colleagues above, e ...read more Let me agree 100% with my dear colleagues above, except for the organic zincs, which I agree also 100% on the cons, but only for TRADITIONAL organic zincs. For some special organic incs, such as a proprietary film galvanizing system, the cons become pros as follows: It does not need to be overcoated. Working very effectively as a stand-alone system, it performs powerfully in marine environments (C5M), Also immersed and in transition zones, it has very high sacrificial ability as an anode, resists damage and it is easily repaired with itself.
Jithin Narayanan of JGC Corporation on
November 8, 2017:
Inorganic zinc pros: abrasion resistance, corrosio ...read more Inorganic zinc pros: abrasion resistance, corrosion resistance, applicable in low and high humidity (choose water-based or solvent-based depending on actual humidity), used as internal coating for alcohol tanks like methanol, high temperature resistance, good range of overcoatability, can be used under insulation where temperature is high enough that no water vapor is present. IOZ cons: mud cracking, difficult to control thickness on corners, difficult to repair by same coating, zinc dust generation during application (not safe in crowded site), high skilled labor required, curing takes longer, pinhole on succeeding coat especially in silicone and silicone acrylics, cannot be brush applied. Organic zinc pros: easy to handle and repair, can be brush-applied, suitable for all humidity, overcoating possible with most epoxies, IOZ can be repaired with OZ, no concern of popping up on succeeding coat, no high skilled labor required, barrier effect. Organic zinc cons: not a stand-alone coating, no high temperature resistance, less corrosion protection, cannot be used in marine environments as a single coat, cannot be used as an internal coating, less zinc participation in cathodic reaction, cannot keep long time without overcoating, not as wide a range of applicability as IOZ.
Larry Muzia of Exceletech Coating & Applications, LLC on
November 6, 2017:
Inorganic zinc pros: better abrasion resistance, ...read more Inorganic zinc pros: better abrasion resistance, can be a one- coat protective system in various environments, higher temperature resistance, direct-to-metal zinc contact, better edge protection, excellent protection in marine environments, low temperature cure provided sufficient humidity during cure, long pot life. Inorganic zinc cons: requires proper surface preparation with adequate surface profile, will mudcrack if applied too heavily, requires 50% humidity during cure, topcoat can pinhole without proper technique, requires higher level of applicator skill, overspray control required and increases with higher level of humidity, although appearing hard within hours curing should be confirmed before overcoating, low tensile strength. Organic zinc pros: more user-friendly than inorganic zincs, more tolerant of less than perfect surface prep, does not cause pinholing of topcoats, rapid overcoating with many formulations. Cons: must be overcoated, zinc being encapsulated in organic resin does not give the same level of sacrificial ability of anode/cathode does not resist handling damage as well as inorganic zinc.