April 8 - April 14, 2013
What are the limitations of rust-encapsulating coatings?
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eric sinnema of glice naano on
April 19, 2013:
You don't want to encapsulate a problem. You penetrate it to t\he bottom of its morphological depth and passivate the corrosion.After drying, we flame the surface to eliminate oily elements on the surface. Finally, we apply a Si-based nano coating, ion-plasma applied.
Tom Schwerdt of Texas Department of Transportation on
April 18, 2013:
On the flip side, the structural engineers around here typically don't want pack rust between plates removed too deeply, out of concern the plates will be largely unsupported. The exception is if the plates are being completely pulled off, straightened or replaced and re-bolted.
Larry Muzia of Exceletech Coating & Applications, LLC on
April 15, 2013:
It becomes a subjective answer. Heavy scale rust is a bad candidate to encapsulate. As an oxide film is porous, it is important to clean and remove trapped contaminants to eliminate/minimize the forces which can increase the driving force to attract the electrolyte. Typically, a barrier-type coating is utilized to overcoat a tightly adhered rust layer, with the intention of eliminating available oxygen and electrolyte. A sufficient film thickness over tightly adhered, contaminant- free rust can provide extended surface life; and I have been involved in projects achieving over a decade of extended service, to include salt warehouses.It is my experience that well adhered rust which is suitably cleaned can be successfully overcoated; however, emphasis must be placed on correct procedures and proper coating technology.
Javier Figarella of Ecotek Investments Inc. on
April 15, 2013:
I completly agree. The most secure and ecological and economic way to prevent further corrosión is to totally eliminate rust by chemical methods. Encapsulating rust is the worst thing you can do. Rust converters are the best option when they are applied in concordance whit the right standards
Michael Beitzel of Modjeski & Masters inc on
April 15, 2013:
Pack rust or crevice corrosion is the cancer of the structural steel life span. No cures are in place except complete removal of the tumor. All the rest is just chemotherapy that at best slows the growth. Hydrophobic coatings appear to be the most effective supplemented with caulking to prevent moisture traps. Even with removal the corrosion-caused cavities formed need to be filled to prevent recurrence of the corrosion.
Jay Barstow of Aeroflor Coating Services on
April 12, 2013:
Encapsulating or impregnating? Big difference! As Per (Scandinavian?) stated above, encapsulation can be a stop-gap measure in hostile environment, whereas impregnation actually creates a hybrid, corrosion resistant material (providing rust is tight and loose scale [and any salt] is removed).
Per Gabrielsson of Free Lance Consultations and Inspections on
April 8, 2013:
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They are there only as "monkey shines," because oxygen and moisture will eventually enter the rust through the coating and expand it - and there you stand with your bare hands and realize that you actually had gained nothing, but extra work.
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