Atmospheric corrosion severity and the precision of salt deposition measurements made by the wet candle method

Abstract

The Wet Candle technique quantifies the dry deposition flux of atmospheric species onto a gauze wick. Salt deposition flux is used to rate the corrosion severity of outdoor test sites. It is important to quantify the precision of the Wet Candle method if the results are used to compare the atmospheric corrosivity of various sites. An analysis of Wet Candle precision is conducted in terms of repeatability and reproducibility. The percent deviation is 3.2% for chloride repeatability and 3.3% for chloride reproducibility. Interval testing is conducted to determine if weekly intervals added together yield a deposition flux similar to a month-long interval. Weekly results are assessed alongside meteorological data to correlate atmospheric conditions to dry deposition. Finally, the erroneous contribution of chloride from various types of gloves to deposition flux is quantified. Based on these findings, recommendations are made on how to avoid various sources of error.