The owner mounted the sampler against a pine board and framed it in a manner that allowed the sampler to touch the front glass. The sampler eventually came to the local museum which hung it on the wall in a period room. Unfortunately, this museum, like many in our state, could afford no heat in the winter. In an extreme temperature drop, frost formed on the inside of the glass directly over the sampler. When the frost melted, the sampler absorbed water where it touched the glass.
Wooden boards are highly acidic, and the water from the frost created an acidic solution.
The dark stains appeared later, evidence of an acidic solution actually eating away at the sampler. The damaged sampler needed two kinds of preventive care. For now, let s turn our attention to heat and humidity control. Fluctuations in temperature and relative humidity cause dimensional change in all objects. The more extreme the fluctuation, the greater the change.