Coatings for Galvanized Structures

Galvanized structures often need to be coated.  New structures may be going into service conditions where the zinc layer will not be able to form the familiar patina and thus will self-sacrifice prematurely.  On old structures, the zinc may be damaged or simply depleted.  Historically, the only recognized and permanent form of surface preparation has been abrasive blasting, a process that removes part of the zinc and often fractures what is left.  It’s invasive, expensive and, because of multiple variables, often gives inconsistent results.   Less disruptive approaches such as chemical pretreatments have been tried many times, but work only in mild environments.  Long term, nothing other than blasting works on hot dip galvanized steel: - that is, until the invention of GalvaGrip and GalvaClad.

GalvaGrip is Madison’s unique Surface Conditioner / Adhesion Promoter that eliminates the need for aggressive blasting. This environmentally-friendly, soap-like compound is simply brushed or sprayed on the metal surface.  In about ten minutes, it dissolves oxidation, removes contaminants and lays down a layer of Madison’s exclusive AP-50 Adhesion Promoter.  After the “spent” GalvaGrip is washed away with ordinary tap water, the surface is ready to coat.

There is a choice of several topcoats, each of which contains the same AP-50 Adhesion Promoter.  They work synergistically over the GalvaGrip-prepared surface to provide adhesion comparable to a costly grit blast.

Two of the available topcoats are GalvaClad Aromatic and GalvaClad Aliphatic.  These instant-setting self-priming, one-coat products are solvent-free and non-flammable, making them ideal for fast throughput, for example in a production setting.  The Aromatic version is the workhorse of the pair, tough and strong; however, where the end user wants color and gloss retention as well, the Aliphatic version is the correct choice.  A third option is GalvaClad Liquid Zinc, also containing AP-50.  This paint-like Zinc Rich Primer adheres tenaciously, is extremely corrosion resistant and can be used on its own (it has a silver metallic look) or topcoated with a variety of Madison products such as AcrylaThane or TufSheen PreCatalyzed.  We can even craft a custom made solution by formulating AP-50 into just about any Madison coating your want to use.

If you prefer to blast anyway for some reason (e.g. required by an old specification or to remove an extremely heavy layer of corrosion product), GalvaClad products are still the optimum choice.  All other things being equal, they will increase adhesion by 50% or more, especially where the blasting equipment, media and other factors are not optimal and the results might otherwise be marginal.  It is also of interest where the customer is already getting good results but wants to drive down the cost and severity of the blast. 

Think, then, of GalvaClad in two ways; as a way of cutting back on the blast and as a way of eliminating it altogether.

To find out more about the history and development of GalvaClad and an overview of the products, click here to view our press release dated August 29, 2008 announcing this technology.

For additional information regarding technical aspects and laboratory test results, click here for our latest InfoTech Bulletin.

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Copyright © 2008 Madison Chemical Industries, Inc.  All rights reserved. AcrylaThane®, AlumiZinc®, CorroClad®, CorroCote®, CorroPipe®, CorroPrime®, CorroZinc®, FibreThane®, Flexcel®, GemThane®, GemThane AquaTech®, GemThane AquaTech STC®, HydroThane™, MariThane®, Maxxam™,  PilingPro®, PoleClad®, PolySheen™, TufSheen®, UltraLiner™, UltraPrime™, Gemthane® ,FussionClad™, GalvaClad™, NanoSheild™, PrepCrete™, FerroGrip™, GalvaGrip™ and Madison AP-50 Adhesion Promoter™ are trademarks of Madison Chemical Industries, Inc. We are an ISO 9001:2000 registered company.