July 17 - July 23, 2016

During newbuilding, do I have to stripe coat edges if I am using an edge retention primer?

Selected Answers

From Erik Andreassen of CPS on September 30, 2019:
Stripe coating is always required on edges,corners,welds,holes and angles. Why? Because these are the main areas to beak down first due to lack of correct coating prior to spray application. Always apply primers by brush, not rollers, mainly because of air entrapment..

From Rick Simpson of Global Coatings Consulting Lts on July 22, 2016:
On all projects, I insist that all edges are radiused, checked for minimum 2mm radius, then blast-cleaned and stripe-coated. As Simon has pointed out, edge-retention primers do not compensate for the loss of DFT in these areas. Where flash-rusting can occur rapidly in coastal regions, I instruct the painters to apply a primer coat to seal the blast. Once it has dried, the stripe-coating can then be done. Either way, it must be done.

From Per Gabrielsson of Free Lance Consultations and Inspections on July 21, 2016:
One thing to remember when you make the stripe coating is to use brushes. If striping with rollers, the distribution of paint is doubtful and the coating is just slashed on, not worked mechanically. Just take a glass plate and roll and look at the plate faced to the sun. Then you will see how good your stripe coating is.

From MARIANA HUHULEA of Seaquest MPM on July 21, 2016:
You definitely need to do so. And carry out an edge preparation, as well. Although the chemistry of edge-retention primers has significantly improved, they cannot do the work (corrosion protection) alone. From three-pass grinding and one or two stripe coats of immersed compartments' edges to a minimal one-go grinding plus one stripe coat of the others, this is to date, as far as I am concerned, the key to their long-term protection.

From Simon Wadsworth of COWI on July 20, 2016:
Yes, you need to stripe-coat. I am not a coating specialist, but my understanding is that edge-retentive coatings reduce but do not eliminate the reduction in thickness of a liquid paint film due to surface tension. There may be scope for reducing the number of build or stripe coats, but this would need to be justified by experimental evidence.

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