19th-century stucco decoration is crumbling from salt crystallization cycles. Conservation chemistry identified sodium sulfate as the destructive agent, migrating from groundwater through capillary action.
A Monastery of Brick and Mortar
The Maha Aungmye Bonzan Monastery, also called Me Nu Ok Kyaung, is an outlier in Burmese monastic architecture. Queen Me Nu, the wife of King Bagyidaw of the Konbaung dynasty, commissioned its construction in 1818. Unlike traditional monasteries of the era, which were built from wood, this structure is made entirely of brick and covered in ornate stucco. The design mimics the multi-tiered roofs and elaborate decorations of its wooden counterparts, translating the art of woodcarving into the medium of sculpted plaster.
The building is in the former capital city of Inwa, an area with a high water table near the Irrawaddy River. This proximity to groundwater is the source of the monastery's persistent conservation problem. Porous building materials, like the historic bricks and lime-based stucco, act like a wick. Groundwater containing dissolved mineral salts is drawn upwards through the masonry by capillary action. As the water evaporates from the surface, it leaves the salts behind. This process is the starting point for a destructive cycle that threatens the building's elaborate exterior.
The Chemistry of Crumbling
The primary chemical culprit identified at Maha Aungmye Bonzan is sodium sulfate (Na₂SO₄), a particularly aggressive salt. This salt exists in different hydrated forms, and its transitions between them generate immense physical stress within the pores of the stucco and brick. As the salt solution rises and the water evaporates, the sodium sulfate crystallizes. This initial crystallization is known as efflorescence when it appears as a white, powdery layer on the surface.
The more destructive process is subflorescence, where crystals form just beneath the surface. As ambient humidity and temperature fluctuate, the sodium sulfate crystals dissolve and recrystallize, growing larger with each cycle. The pressure exerted by these expanding crystals can exceed the tensile strength of the stucco, causing it to blister, flake, and disintegrate. Studies on similar salt damage in historic buildings have shown that sodium sulfate is one of the most destructive salts due to these repeated phase transitions. The complex floral patterns and mythical figures sculpted from stucco nearly two centuries ago are now actively being pushed apart from the inside by these microscopic chemical forces.
💡Fun Facts
The monastery was damaged by a major earthquake in 1838 and repaired in 1873 by Sinphyumashin, Queen Me Nu's daughter.
Its common name, Me Nu Ok Kyaung, literally translates to "Me Nu's Brick Monastery".
The structure was built as a residence for the Royal Abbot, Nyaunggan Sayadaw U Po.
At its dedication ceremony, 68 prisoners were reportedly released.
The site is generally accessible during daylight hours, roughly 8:00 AM to 6:00 PM.
Admission
Access is typically included in the Inwa Archaeological Zone ticket, which costs around K10,000-K15,000 (US$10).
Accessibility
The site has uneven, unpaved ground. Reaching Inwa from Mandalay involves a boat trip across the river, and transportation around the archaeological zone is usually by horse-drawn cart or bicycle.
The Maha Aungmye Bonzan Stucco ConservationMandalay Region, Myanmar