Mold and mildew (fungal) growth on coatings used on the interior of Navy ships has potential deleterious effects on coating performance, including corrosion protection and prevention, and on the health of Ship’s Force personnel. Fungi will digest plasticizers, hydrocarbons, and other coating compounds decreasing the coating’s flexibility and promoting subsequent cracking, exacerbating risk and damage by allowing fungal proliferation deeper into the coating and eventually to the substrate. Currently, the Navy has no fungal-inhibitive coatings on ships and weapons platforms. Commercial paint manufacturers have proprietary technologies that can be incorporated into currently qualified coatings and prevent the occurrence of fungal growth on coatings. This study will evaluate the effectiveness the various technologies compared to currently specified coatings, such as MIL-PRF-24596, MIL-DTL-24607, condensation control coatings and insulation, and anti-corrosive primers, such as MIL-PRF-23236 and MILDTL-24441, Type IV. In addition, alternative environmentally friendly cleaners and disinfectants will be assessed for their ability to deactivate fungal spores and prevent the spread of fungus. The current most common method is to use bleach. However, work from the Naval Research Laboratory South, Stennis Space Center, MS [NRL-South] has shown that bleach does not effectively kill the spores and serves as a spreading mechanism for the spores, exacerbating the problem and causing further coating failure. Coating failure leads to replacement of the coating, buildup of waste, and increase in the use of solvents and cleaners that are deleterious to the environment.
Demonstration of the effectiveness of fungal-inhibitive coatings will take place in three concurrent/interdependent phases. Ship surveys (Phase I) will be utilized to define problem areas, severity, and sampling/identification of fungi. Laboratory testing (Phase II) will focus on evaluating the effect of fungal growth on selected coatings, the effectiveness of inhibitive technologies on preventing fungal growth, and ensuring that inhibitive coatings meet the requirements of the respective coating specification. In addition, cleaners will be tested for efficacy on deactivating fungal spores, removal of fungal biofilms, and mechanical/chemical impacts on coatings and substrate. Phase III will perform a ship demonstration of the highest performing fungal-inhibitive coatings with a control coating in an area where fungal growth is a known problem. Success for this effort will result in the following deliverables: (Phase I) a novel survey and identification of fungi growing on Naval Sea Systems Command weapons platforms, (Phase II) identification of high performing inhibitive coatings, in-depth understanding of fungal impact on coatings, and identification of a high performing, low impact, environmentally friendly cleaner(s), and (Phase III) successful in-service demonstration of fungal-inhibitive coatings. Point of contacts for this collaborative effort will be Naval Surface Warfare Center Carderock Division (Point of Contact [POC]: Dr. Charles White), NRL-South (POC: Dr. Jason Lee), and Elzly Technology Corp (POC: Mr. Patrick Cassidy).
Measurement of the degradative effects on coatings due to fungal growth and cleaning procedures will provide a quantifiable metric for the recommendation of new requirements to the coating and corrosion Technical Warrant and transition of the technology to the fleet. This three-year project will document the location and severity of fungi on Navy ships, measure coating degradation, and demonstrate commercially available products that inhibit fungal growth and increase service life compared to the currently used coatings.