Problem Solving Forum
April 24 - April 30, 2016
Why do we still need to stripe coat given the array of high-solids, edge-retentive coatings currently on the market?
William Feliciano of NYS Dept. of Transportation on
January 8, 2019:
Regardless of the claims made by a coating manufac ...read more Regardless of the claims made by a coating manufacturer with respect to their product's edge-retentive properties, in-service performance will ultimately rely on the quality of application. For specifications that are competitively bid, a stripe coat not only makes sense for all the technical reasons mentioned here, but it also buys the facility owner edge protection insurance against less-than-stellar spray application. Bridge painting projects tend to inflict high user costs. With tight budgets and increased federal expectations, the expected service-life for paint on federally aided structures has creeped to 20-25+ years. At least on bridges, it doesn't make sense not to stripe.
Jonathan Rausch of That's private on
January 6, 2019:
I only stripe coat if the substrate is NOT getting ...read more I only stripe coat if the substrate is NOT getting a primer.
MARIANA HUHULEA of Seaquest MPM on
May 4, 2016:
When it comes to edges protection against corrosio ...read more When it comes to edges protection against corrosion, I would say stripe coating is a must. Application by roller is not the best solution; however, it is better than not do it at all. On weld seams, however, I would be more cautious as stripe coating may increase the DFT and cause cracking, especially for modified epoxies. Thus, prior to project commencement, all relevant parties must agree on where and how many stripe coats should be applied, depending on chosen coating materials.
Warren Brand of Chicago Corrosion Group on
April 29, 2016:
From a practical perspective (I was a contractor f ...read more From a practical perspective (I was a contractor for about 25 years prior to becoming a consultant), it's a very fast, proportionately low-cost task which is critical for any long-term paint or coating application, particularly given the difficulty in accurately measuring the DFT on edges. There's simply no compelling reason not to do it.
Alfredo Claussen of Instituto Mexicano del Petroleo on
April 27, 2016:
In addition to the physical force (resulting from ...read more In addition to the physical force (resulting from the surface tension of the still liquid paint, previous to "drying") already mentioned by Per Gabrielsson, there is another physical phenomenon that compounds the situation. This phenomenon tends to simultaneously "pull" the coating away, not only from the edges, but from internal angles in inside corners and crevices, as well as from weld seams, too. It is derived from the residual stresses created when the coating resin matrix suffers an inevitable "shrinking" due to chemical reactions in polymer coatings, creating stressed regions where the coating failure is more prevalent than on flat surfaces. As the grinding of the steel beam edges and rounding or smoothing of weld edges is a lengthy and thus costly process, the usual (and undoubtably) best next thing to do is stripe-coating, regardless of any "edge-retentive" coating vendor claims. Several years ago, I wrote a paper on the subject of residual stresses in coating failures; you can see it at Academia.edu, albeit, it is written in Spanish! (https://www.academia.edu/3474229/_FEN%C3%93MENO_DE_GENERACI%C3%93N_DE_ESFUERZOS_RESIDUALES_EN_RECUBRIMIENTOS_ANTICORROSIVOS_)
Gerald Holton Jr of Specialty Polymer Coatings USA iNC on
April 27, 2016:
"Edge-retentive" is a loose term. It all depends u ...read more "Edge-retentive" is a loose term. It all depends upon the coating being applied and method of application. When applying via spray, a stripe coat is a warm fuzzy that provides you with added confidence that there will be less likelihood of a holiday. With hand-applied products, based upon surface to be coated, the stripe coat can be applied prior to or as final coat upon completion of application. I agree that use of a roller may not provide the mils required
Per Gabrielsson of Free Lance Consultations and Inspections on
April 26, 2016:
Physical forces will move the coating from the ste ...read more Physical forces will move the coating from the steel edge. Stripe coating is one of the most essential steps in the coating process and should always be applied by round brushes. If rolled, the stripe coat will only be "slashed" onto the surface and not be worked in around, e.g., manual welds.