87/100
Overall TDI Score
94%
Efficacy Retention
150
Surfaces Tested
18 mo
Study Duration
Abstract
This 18-month longitudinal study evaluates inorganic antimicrobial coating durability under extreme humidity conditions (70-95% RH) with daily condensation cycles—conditions uniquely challenging in Singapore's tropical climate. Testing was conducted across 150 surfaces in bathrooms, kitchens, and air-conditioned bedrooms experiencing regular wall condensation.
The study introduces the "Tropical Durability Index (TDI)," a novel composite metric measuring antimicrobial efficacy, coating integrity, and ion retention under condensation stress. Results demonstrate 94% average efficacy retention at 18 months, with TDI scores of 87/100.
Results
"TDI scores above 75 indicate coating remains effective; proactive reapplication recommended when TDI drops below 80"— Tropical Durability Index Threshold
TDI by Environment
| Environment | TDI Score | Avg RH | Condensation Freq | Efficacy Retention |
|---|---|---|---|---|
| Bathroom | 82/100 | 92% RH | 2-3x daily | 91% |
| Kitchen | 89/100 | 78% RH | 1-2x daily | 95% |
| AC Bedroom | 91/100 | 82% RH | 1x daily | 96% |
Failure Mode Analysis
| Failure Mode | Incidence | Onset Time | Primary Cause |
|---|---|---|---|
| Ion Depletion | 8% | 14+ months | Heavy condensation + frequent cleaning |
| Chalking | 3% | 12+ months | Direct water pooling without drainage |
| Biofilm Rebound | 5% | 16+ months | Preceded by ion depletion |
Conclusion
Key Takeaways
- Shield23pro maintains 94% average efficacy after 18 months at 70-95% RH with daily condensation
- TDI provides reliable predictive metric for maintenance scheduling (threshold: 80)
- Bathrooms require 15-18 month reapplication; kitchens/bedrooms support 18-24 months
- Ion depletion is the primary failure mode indicator—address before biofilm rebound occurs
Recommendations
- Implement TDI monitoring for high-humidity environments (quarterly assessment)
- Schedule proactive reapplication when TDI drops below 80
- Bathrooms: 15-18 month reapplication intervals
- Kitchens/AC bedrooms: 18-24 month reapplication intervals
References
- Meteorological Service Singapore. (2024). Singapore Climate Humidity Data 2019-2024.
- National Environment Agency. (2024). Indoor Air Quality Guidelines for Tropical Buildings.
- Wong, K.L., & Tan, S.H. (2023). Condensation Dynamics in Air-Conditioned Tropical Residences.
- ISO 22196:2011. Measurement of Antibacterial Activity on Plastics and Other Non-Porous Surfaces.