Quantifying Thickness Change of Antifouling Coatings Upon Exposure To Artificial Seawater
Abstract
Whether and by how much hull coating systems swell and whether or how this impacts paint thickness measurements has long been debated. If swelling does occur and it is significant, it could at least in part help explain unexpected variability observed in past data sets, especially if swelling is a function of environmental conditions such as exposure time, water chemistry, salinity, and water temperature. If swelling is not significant, then other potential factors that may impact DFT measurement accuracy must be explored. We quantified the impact of seawater exposure on paint thickness under controlled conditions of pH, temperature, and salinity on three replicate panels of four coating systems. In addition, we attempted to quantify the impact of coating and substrate roughness on measurement error. We used a precision template and probe stand to repeatedly quantify DFT at the same 12 spots on each panel over 90-days. Based on our results, copper ablative antifouling hull coatings exposed to artificial seawater for 3 months at room temperature do not significantly swell. If any DFT change does occur, it is < 1 mil. Hypothetical DFT changes of less than one mil due to swelling would not account for the much larger discrepancies between a subset of field data sets mentioned above which showed quite large decreases in DFT over very short periods of time or quite small increases in DFT over longer periods of time. We believe that measurement error, not paint swelling, was the most significant contributing factor to the error associated the reported data sets. In the end we summarize a series of lessons learned for both laboratory and field DFT measurement techniques.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 24, 2008
- Accession Number
- AD1068263
Entities
People
- Elissa M. Bumiller
- Elizabeth G. Haslbeck
- Eric R. Holm
Organizations
- Naval Surface Warfare Center