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Paint's Perpetual Problems
We considered several headings for this section and settled on Paints Perpetual Problems. Another possibility was Proper-Prior-Preparation-Prevents-Poor-Paint-Performance. Perhaps so, but the seven Ps were a little too much for a title. Besides, paints problems are not limited to surface preparation. That's just where the problems begin. Some paint failures are due to poor application, and other problems are inherent in the paint itself.Exaggerated sales promises and owners' high expectations contribute to owners' disappointment and frustration with paint performance. Paint coatings just do not last as long as structure owners would like, and certainly not as long as metalizing.
Have you noticed how many paint consulting firms and commercial paint labs offer "failure analysis" service? Its hard to believe that failure analysis is such a integral part of the paint industry well maybe its not so surprising. We will explore this further!
The use and validity of accelerated exposure testing of paint coatings is called into question in the "Journal of Protective Coatings and Linings" article entitled, "ASTMs New Coating Test Method Addresses Interactive Effects of Weathering and Corrosion". From that article we quote:
"For years, the coatings industry employed ASTM B 117 to evaluate the corrosion resistant properties of coatings. Research conducted during the last 15 years has proven that this method does not correlate with actual atmospheric exposures. Today with the reformulation of many protective coatings to comply with VOC regulations, an accurate corrosion acceleration test method is needed more than ever. ASTM D 5894 addresses this need. This new method offers an improved technique for comparing the relative durability of coatings. Its use can make the difference between selecting a coating system that affords effective protection and one that fails."
- JPCL, September 1998, page 61
Do paint manufacturers really claim that their new coatings will last for 20 years? Well, these new coatings have not been in use for 20 years; after all, they are "new". So, are the manufacturers relying on accelerated tests to predict the service life for their new products? Challenge these claims of very-long service life.
Again quoting
" the scope of the new ASTM standard is limited to the assessment of relative coating performance and not directly to actual coating life."
- JPCL, September 1998, page 52
You will have to wait 20 years to learn how effective, or ineffective, the "new paints" are over that period. An accelerated test cannot establish a track record! Metalizing has a 90-year record of success!
In "Trouble with Zinc-Rich Primers, Part 1: Non-Topcoated Systems", we can read about the problems associated with the use of zinc rich paints. The problems described include Zinc Sedimentation and Its Effect on Primer Performance, Zinc Reactivity, Control of Gassing, Special Problems with Two-Pack Epoxy Systems, and Adhesion to the Substrate.
- JPCL, August 1998, pages 29-46
Metalizing may be the simpler, more applicator-friendly process, as well as the more reliable coating over a 30-year life! Simply blast the steel, spray the wire, seal the coating, and you are done!
In "Trouble with Zinc-Rich Primers II Multi-Coat Paint Systems", we read about the problems with multi-coat paint systems. The problems include: Intercoat Adhesion Difficulties, De-adhesion from System Design Problems, De-adhesion due to Saponification, De-Adhesion from Contamination, Cohesive Failure Vertical Cohesive Failure (Mudcracking), Lateral Cohesive Failure (Zinc Splitting), Effect of Cure Deficiencies, Topcoat bubbling, and Cohesive Weakening of Zinc Primer after Recoating.
- JPCL, September 1998, pp 34-48
Sorry, the only thing that will make the paint work better is a layer of sprayed metal under it!
At the 1998 International Bridge Conference held at the Hilton Hotel in Pittsburgh, a paint industry spokesman warned:
"Unless the longest maintenance free coatings are used, the bridge painting deficit will continue to grow"
.We dig a deeper hole by continuing to paint and re-paint hoping for a 10-15 year coating life. Assume a state has 10,000 steel bridges to maintain, and paints 100 bridges per year. That means that each bridge is on a repainting schedule of once every 100 years!
Reliance on short-lived coatings has already created a maintenance crisis.
The "Journal of Protective Coatings and Linings" quoted the publisher of a prominent paint publication in his August 1997 article "Weapons Directed Against Corrosion". In that article the publisher wrote:
"After highlighting the importance of thorough surface preparation to coating performance, [he] warns that metalizing poses a serious threat to the market shares of protective coatings, especially given its long reported service life and recently reduced costs."
- JPCL, December 1997, page 94
The publisher was alerting his readership that metalizing is now cost competitive with the best of the paints. He neglected to mention that paints are not yet performance competitive with metalizing.
He was trying to rally the troops against the "threat" posed by the evil metalizing industry.
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