IndMar Resource Library
Specification Writing Guide
IndMarCoatings will assist in the preparation of specifications for customer or owner projects. This includes
on-site inspections and recommendations. As a general guide, the following information is provided.
Coating integrity and service life will be reduced because of improperly prepared surfaces. Up to 80% of all coatings failures can be directly attributed to inadequate surface preparation that affects coating adhesion. Selection and implementation of proper surface preparation ensures coating adhesion to the substrate and prolongs the service life of the coating system.
Selection of the proper method of surface preparation depends on:
the substrate, environment, and the
expected service life of the coating system.
Economics, surface contamination, and the effect on the substrate will also influence the selection of surface preparation
Regularly scheduled maintenance
For a protective coating system to provide maximum protection, a regularly scheduled program of inspection, touch-up and maintenance is required. The system should be inspected at:
- six-month intervals for corrosive areas
- 12-18 months or longer for less severe exposures
For atmospheric service, when up to 10 percent of the total area has been
chemically or physically damaged, eroded, or rusted, it may be Power Tool Cleaned, spot primed, and finished with the same coating as originally used.
For immersion service, when up to 10 percent of the total area has failed, spot blasting back to at least one-inch into sound film, feathering the edges, and re-coating with the original system is required.
When the coating system has deteriorated to approximately 33 percent of the total area, it may be more economical to consider a complete re-coat.
Weathering, abrasion, impingement
- When film has eroded due to weathering or worn thin due to abrasion or impingement (with no rusting), the surface contaminants may be removed through:
waterblasting (approximately 2,000
psi, over 4 gallons per minute) with emulsifying agents or cleaners , rinsing, drying re-coating with the recommended finish coat(s) to maintain or even extend the original
design life of the coating system
Roughening of the surface will improve the adhesion of the subsequent coats.