Conservation Case Study • Research Archive
Tropical Model: 2-Year Observation Case Post-treatment monitoring in real tropical conditions
Published: March 2026•
Location: Puchong, Selangor•
Keywords: Tropical Model, Oil Painting, Observation Study
Last Data Update: April 2026 (Month 0 / Baseline) | Next Scheduled Inspection: May 2026
Technical and safety information for Paraloid B-72 and Laropal A81 were consulted from the manufacturer's documentation provided by CTS – Conservazione Tessile Sistemi and BASF/Kremer.
Project Investigator
Tony Ng Chit Keong
Independent Oil Painting Conservator, Malaysia
Role: Malaysia conservator responsible for treatment, monitoring design, ATP testing, environmental logging, and long-term documentation.
1. Project Abstract
This case documents a two-year observational study following the full application of the MTC (Multi-Layer Tropical Conservation) Model on a contemporary oil painting. The treatment strictly follows the MTC structure, including the application of an isolation layer (Paraloid B-72) and a sacrificial layer (Laropal A81), without the introduction of any retouching layer, as no visual reintegration was required. Following treatment, the artwork was returned to its original, uncontrolled tropical environment. No artificial climate stabilization was introduced. The purpose of this study is not to produce definitive conclusions, but to document material behaviour, environmental interaction, and system stability over time under real-world conditions. All observations should be understood as conditional and subject to revision based on long-term monitoring.
2. Project Timeline & Status
Month 0
Completed
Baseline treatment, varnish application & documentation
April 2026
Month 1 (Y1-M1)
Pending
First monthly inspection & ATP swabbing
Scheduled: May 2026
Months 2 - 23
Upcoming
Routine monthly environmental monitoring
June 2026 - April 2028
Month 24 (Y2-M12)
Upcoming
Final evaluation, report synthesis & conclusion
May 2028
3. Background
Oil paintings in tropical environments are continuously exposed to high humidity, temperature fluctuation, and airborne particulate matter.
In such conditions, long-term stability is influenced not only by biological factors, but also by material interaction, moisture exchange, and layer behaviour over time.
Rather than focusing on reactive restoration, this project adopts a structured, preventive approach through the MTC Model, which introduces defined material layers to manage interaction between the original paint surface and the surrounding environment.
This case does not aim to eliminate environmental influence, but to observe how a controlled material system behaves within it.
4. MTC Model Statement
The MTC (Multi-Layer Tropical Conservation) Model is a structured conservation approach developed in response to the conditions of tropical environments, where humidity, temperature fluctuation, and material instability are persistent factors.
Rather than relying on a single treatment layer, the model introduces a controlled multi-layer system consisting of an isolation layer and a sacrificial layer, while preserving the original paint structure.
The purpose of this model is not to eliminate environmental influence, but to manage interaction between materials over time. It is designed to allow maintenance, reversibility, and long-term observation under real-world conditions.
This model should be understood as an evolving framework, informed by ongoing case-based observation rather than fixed conclusions.
Full framework reference:
https://tonyngchitkeong.com/MTC_Model/Malaysia_Tropical_Conservation_Model.html
5. Potential Fungal Genera in Tropical Heritage Environments
The following fungal genera are frequently reported in tropical and high-humidity environments and are known to contribute to the biodeterioration of organic cultural heritage materials such as oil paintings, canvas supports, paper, and varnish layers. These genera are included here as a reference framework for potential microbial risks in tropical climates (Sterflinger 2010).
| Genus | Typical Substrate | Potential Risk to Oil Paintings |
|---|---|---|
| Aspergillus | organic binders, canvas | pigment staining and surface colonization |
| Penicillium | varnish layers, canvas | discoloration and spore spread |
| Cladosporium | humid surfaces | surface colonization |
| Alternaria | organic materials | pigment alteration and staining |
Table 1 — Fungal genera commonly associated with biodeterioration of cultural heritage materials in humid climates (after Sterflinger 2010).
6. Conservation Objective
• To implement the MTC Model as a structured, multi-layer conservation system
• To establish a stable isolation layer using Paraloid B-72
• To introduce a sacrificial layer (Laropal A81) as a controlled interface for future maintenance
• To document system behaviour under uncontrolled tropical conditions
• To generate observational data for long-term evaluation and future refinement
7. Experimental Methodology & Rationale
This project is not designed as a controlled experiment, but as a long-term observational study based on real collection conditions.
Methodological Structure (MTC Model):
• Original structure (support and paint layer) – left unchanged
• Isolation layer – Paraloid B-72
• Retouching layer – not applied
• Sacrificial layer – Laropal A81
This layered system separates intervention materials from the original surface while allowing future maintenance and reversibility.
Environmental Context:
After treatment, the artwork was returned to its original location without environmental control. This includes natural fluctuations in humidity, temperature, and airborne exposure typical of tropical indoor conditions.
Monitoring Approach:
• Environmental readings
• ATP surface testing
• Visual inspection
• Surface condition tracking
Rationale:
The purpose is to document behaviour over time rather than confirm a predefined outcome. All findings are considered provisional and subject to change.
8. Methodological Disclaimer
This project represents an observational monitoring study conducted under real collection conditions. Unlike laboratory-based conservation experiments, environmental variables such as humidity, temperature, and airborne biological exposure were not artificially controlled.
The data presented therefore reflect the natural environmental fluctuations typical of tropical climates and are intended to provide practical insights into preventive conservation strategies under real-world conditions.
9. Study Limitations
This study represents a single-object monitoring project conducted under real-world collection conditions rather than a controlled laboratory environment. Environmental variables such as humidity and airborne biological exposure were not experimentally regulated. The observations presented therefore represent case-specific monitoring data rather than generalized experimental conclusions.
10. Treatment Overview
The full assessment, detection, and judgment processes leading to this treatment are extensively documented in case study TPA281-2026-005.
Following that assessment, the conservation treatment was carried out according to the MTC Model:
Surface Preparation
Mechanical cleaning and localized solvent action were performed to reduce surface contaminants prior to layer application.
Isolation Layer
Paraloid B-72 was applied as a stable, reversible isolation layer separating the original paint surface from subsequent materials.
Sacrificial Layer
Laropal A81 was introduced as a removable protective layer designed to receive environmental impact and allow future maintenance without affecting the original surface.
No retouching layer was applied, as visual reintegration was not required.
12. Research Significance
This case study provides empirical baseline data for adopting proactive preventive conservation in Southeast Asian environments, rather than waiting for bio-deterioration to occur. The successful utilization of Paraloid B-72, coupled with passive microclimate framing, offers a low-maintenance, cost-effective, and highly protective standard operating procedure for the preservation of modern oil paintings in challenging tropical climates. This protocol significantly reduces the future need for invasive restorative cleaning, thereby preserving the original integrity of the artist's work from day one.
13. Decision Log
Observation Period: Y1-M0
Status: Initial baseline observation
Trigger ObservationArtwork reinstalled in original display location.
Regional ambient humidity (Selangor, Puchong) recorded at approximately 75%, while indoor environmental RH at the artwork location measured at 80.6%, with temperature at 29.8°C.
A surface reading taken at the backing board recorded approximately 65.8%.
ATP surface reading recorded at 0 RLU.
InterpretationInitial baseline data indicates elevated indoor humidity conditions (80.6% RH), exceeding the regional ambient reference.
A lower moisture response is observed at the backing board surface (65.8%) compared to the surrounding environment, suggesting a difference between environmental RH and material response at this stage.
ATP readings do not indicate detectable microbial activity.
No internal microclimate data is available at this point.
This dataset serves as a reference snapshot for subsequent observations.
DecisionNo intervention at this stage.
RationaleThis initial dataset establishes a baseline under relatively high humidity conditions.
Given the limited scope of data at this stage, no assessment of internal environmental behavior or system performance can be made.
Continued observation is required.
Risk ConsiderationElevated indoor humidity (80.6% RH) may present a potential long-term risk if sustained.
Current data does not indicate immediate risk, but environmental trends remain to be evaluated over time.
Action TakenBaseline data recorded. Routine monitoring initiated.
14. Visual Documentation
Baseline Imaging (Pre-treatment)
Post-Treatment Imaging
Monitoring Comparison
Visible Light / Macro (Microscope)
Visible Light / Close-Up
UV Fluorescence
15. Environmental Data Graphs
Microclimate vs. Ambient Humidity Over Time
ATP Microbial Activity Index (RLU)
16. Quantitative Data Archive
| Observation Period | Temp (°C) | Ambient RH (%) | Inner RH (%) | Wall Moist (%) | Lux | ATP (RLU) |
|---|---|---|---|---|---|---|
| Y1-M0 | 29.8 | 80.6 | 3.7 | 223 | 0 |
17. External Weather Conditions (Google Weather)
Note: The following external meteorological data were recorded on the specific day of each monthly inspection to contextualize potential environmental stresses. Source: Google Weather.
| Observation Period | Ext. Temp (°C) | Precip. Prob. (%) | Ext. RH (%) | Wind (km/h) |
|---|---|---|---|---|
| Y1-M0 | 27 | 59 | 75 | 5 |
18. Observation Notes
| Observation Period | Visual Inspection | Varnish Integrity | Initials |
|---|---|---|---|
| Y1-M0 | No visible mold. Canvas tension stable. | Excellent , no blushing. | T.N. |
References
1. Koob, S. P. (1986). The Use of Paraloid B-72 as an Adhesive. Studies in Conservation.
2. Learner, T. (2004). Analysis of Modern Paints. Getty Conservation Institute.
3. Sterflinger, K. (2010). Fungi and the Deterioration of Cultural Heritage.
4. Unković, N. et al. (2015). ATP Bioluminescence Method for Microbial Screening on Cultural Heritage.
Suggested Citation
Ng, Tony Chit Keong. 2026. Tropical Model: 2-Year Observation Case. Post-treatment monitoring in real tropical conditions. Conservation Research Archive.