The objective of this project is to accelerate the transition of a heavy metal-free, biocide-free, zwitterion-based underwater hull coating system to the Department of Defense (subset of Fleets) in order to reduce heavy metal inputs to the environment associated with the current suite of biofouling control coating systems. The unique surface that this innovative technology (current formulation) presents to the environment has been reproduced several times, and has been shown to both minimize the settlement/growth of biofouling (including hard biofouling), and minimize biofouling adhesion (fouling release). The main remaining challenges are primarily tied to scale up, performance validation (longer-term panel and ship testing), and commercialization. The project’s success is strongly linked to a) the establishment of a business relationship between NatureCoat and at least one commercial partner, and b) scale up, and especially the commercial partner’s ability to optimize film properties and increase batch volumes to commercially relevant quantities without negatively affecting biofouling control efficacy.

This project assumes that by project startup one or more commercial partners has established a business relationship with NatureCoat. The first nine months of commercial partner(s) effort (at their own cost) will be devoted to:

  • Formulation optimization (especially pigmentation, film quality, sag)
  • Increasing batch sizes (initially to tens of liters)
  • Providing panels for field screening (static panel) tests

The first year of the Naval Surface Warfare Center Carderock Division (NSWCCD) efforts will be to establish a contract with NatureCoat (advisory role), purchase materials (panels, reference coatings), establish contracts with Florida Institute of Technology (hardware and field testing) and a Navy approved test site (qualification panel testing), coordinate accelerated panel screening tests* and evaluate results, and program requirements (demonstration plans, execution plans, interim reports, etc.). [*NOTE: the cost of the six-month accelerated screening test is covered by the Office of Naval Research (ONR) Environmental Quality/Biofouling Program grants in place with three universities – Florida Institute of Technology, University of Hawaii, and University of Singapore.] The results from the six-month accelerated screening test will be used to determine whether formulation optimization and increase in batch size to Pilot-Scale was successful.

In year two, the commercial partner(s) will turn their attention to scaling up to Production-Scale batch volumes followed by a second round of accelerated panel screening tests. [*see above]. The results from this test will be used to validate performance of Production-Scale processes.

In years three and four, NSWCCD will proceed with more extensive coating performance validation. For the purposes of this project, this work involves: a series of panel tests, ship tests (up to 4 vessels: Navy, – United States Coast Guard [USCG], Army, Military Sealift Command [MSC]), and physical property tests. The majority of the tests are rooted in the US Navy’s performance specification MIL-PRF-24647E, but a subset are included to reduce risk associated with the target vessel classes (frequent hauling and touch up painting). In parallel, the commercial partner(s) will proceed with in-house quality control, panel/ship performance testing, application for Navy qualification (to US Navy MIL-PRF24647E), and other relevant commercialization checkpoints – including all relevant product registration actions, especially in the US. Commercial partners will continue to use in-house, and not ESTCP, funds for this part of their work.

Determinations regarding suitability of the product for transition to the armed services will primarily be made in years five and six. When the results support it, the technology transition process will be accomplished via established service-specific pathways. For the US Navy, the path to qualification and transition is outlined in the performance specification MIL-PRF24647E. This process involves:

  • Vendor request for qualification (Naval Sea Systems Command [NAVSEA] headquarters)
  • NAVSEA request for health hazard assessment (conducted by Navy Marine Corps Public Health Center)
  • Defense Logistics Agency inspection of vendor production facilities
  • Vendor submission of a comprehensive and well-defined data package for review by NAVSEA

When the coating meets the requirements of the Navy’s performance specification, it is listed as a qualified product through incorporation into the Qualified Products Database (QPD; ASSIST website). During a maintenance event (hauling, drydocking), shipyards consult the Navy’s universal guide to coating vessels/ships (Navy Standard Item 009-32) which points the shipyard to the QPD for coating selection. For underwater hull coatings, coating selection is primarily a function of hull material and expected service life.

The project team will facilitate transition of the technology to other services by providing technical briefs and data to key personnel/stakeholders within MSC, Army, and USCG. The project team will work with the armed services to facilitate technology through established service-specific processes (contracts, technical bulletins, and guides).

Technology Description

The zwitterion-based coating that is the focus of this project was developed over the past 10+ years (University of Washington, Dr. Shaoyi Jiang) under ONR Biofouling Program 6.1 and 6.2 funding. A spinoff company (NatureCoat) was formed to facilitate transition of zwitterion-based materials to the marketplace. The focus of this ESTCP project is the low fouling, fouling release (LF/FR) zwitterion-based coating that NatureCoat developed, which is designed to present a surface that retains a tightly bound water layer and thus resists non-specific protein adsorption and cell adhesion. Biomolecules of fouling organisms do not easily displace this strong hydration layer and thus do not strongly adsorb/adhere to the coating surface. In addition, that coating’s fouling release chemistry and the presentation of alternating positive and negative charges further frustrates biofouling adhesion. Zwitterion surfaces deter hard biofouling settlement, but if they do foul, field test data from ONR indicate low pressure waterjet cleaning removes more soft/hard biofouling from N-X-16 than from a commercial off the shelf fouling release coating.

Over recent decades, a wide array of experimental biocide-free coating technologies, including zwitterion-based systems, have been evaluated at ONR-funded university field tests sites. Commercial fouling release coating systems are routinely included in the test matrix as reference materials. Of all of the biocide-free fouling release coatings tested to date, zwitterion-based coatings have outperformed the others over a much longer period of time (nominally two years) and across multiple geographical locations (Florida, Hawaii, and Singapore). The LF/FR zwitterion technology is mature enough and revolutionary enough to have attracted commercial interest of major/global commercial marine coating manufacturers as well as a major yacht coating manufacturer. Commercial partners will establish a business agreement with Naturecoat on formulation optimization, increasing batch size, and bringing the product to the marketplace.


Successful transition of zwitterion-based coatings is expected to reduce environmental impacts associated with commercial biofouling control technologies, including metal inputs [zinc and copper inputs affecting harbor water quality, harbor sediment contamination, and drydock waste streams]. The project team estimates that a changeover from metal-based to metal-free coatings on smaller craft [with short (three years or less) intervals between drydocking] could reduce the environmental inputs of copper and zinc by nearly five tons and just under two tons respectively. In addition, when zwitterion-based coatings more reliably control biofouling compared with biocide-based systems, additional water and air quality benefits could be realized including a lower risk of translocation of non-indigenous species and reduced combustion emissions respectively.

DISTRIBUTION STATEMENT A. Approved for public release: distribution unlimited

  • Soft Coating,