Investigation of Restoration and Conservation of Stone Remains in Thailand

1994 Fiscal Year Final Research Report Summary

• Project/Area Number: 04041106
• Research Category: Grant-in-Aid for international Scientific Research
• Allocation Type: Single-year Grants
• Section: Field Research
• Research Institution: Tokyo National Rsearch Institute of Cultural Properties
• Principal Investigator: NISHIURA Tadateru Tokyo National Rsearch Institute of Cultural Properties, 国際文化財保存修復協力室, 室長 (20099922)
• Co-Investigator(Kenkyū-buntansha): SANGKHANUIKIT P Fine Arts Department of Thailand, 芸術総局・考古部, 部長 ; MAIMAN S Fine Arts Department of Thailand, 芸術総局, 次長 ; IMAZU Setsuo Kashihara Archaeological Institute, 保存科学研究室, 室長 (50250379) ; KUCHITSU Nobuaki Tokyo National Rsearch Institute of Cultural Properties, 国際文化財保存修復協力室, 研究官 (50234456) ; MATSUMOTO Shuji Tokyo National Rsearch Institute of Cultural Properties, 国際文化財保存修復協力室, 主任研究官 (80099960) ; MIURA Sadatoshi Tokyo National Rsearch Institute of Cultural Properties, 保存科学部, 部長 (50099925)
• Project Period (FY): 1992 – 1994
• Keywords: Thailand / Stone Remains / Deterioration / Conservation / Tropical Region

Research Abstract

1. Condition of Deterioration
Stones used in the monuments under the investigation are sandstone, limestone and laterite. Laterite is under stable condition, sandstone is under the worst condition. Condition of deterioration is as follows :
Sandstone is mostly suffering from exfoliation. The cause of deterioration is water both coming from the ground and precipitation. Damage caused by biological infestation under hot and humid tropical environment is also observed.
2. Environmental Survey
Thailand experiences typical hot and humid tropical climate throughout ayar. During the rainy season substantial amount of precipitation can be expected. Such environment affect adversary to monuments under outdoor condition. We have placed measuring device in two of the investigated monuments (Phanom rhung, Muan Tham) in order to monitor more detailed and precise environmental condition. Findings are as follows :
(1) Area is under exceedingly high temperature since daily highest temperature constantly ex ceeds 30*C throughout a year.
(2) Ray is so strong that the temperature as high as 60*C was recorded on the surface of the stone. On the other hand, surface temperature could drop to 10*C during the night because of cooling due to radiation. Difference in temperature during a day is great especially in the winter time.
(3) Amount of precipitation differs greatly during the rainy season and dry seasaon. During the rainy season, though immense amount of precipitation cpuld be recorded, rain rarely last whole day and sun with a strong beam and heavy rain alternate several times a day. This situation helped by high temperature cause rapid evaporation of the rainwater contained inside of the stone, which accelerate the deterioration.
3. Conservation measure
Fine Arts Department of Thailand and the conservation team of TNRICP discussed about the conservation measure for the monuments with a result of the investigation. Both parties agreed as follows :
The main cause of deterioration is water penetrated inside of the structure. Deterioration occurs when such water travels toward the surface of the stone and evaporates from the surface. Basic principle of conservation in this case is to avoid penetrated water remain inside of the structure.