In November 2018, the CAC began a testing program to
evaluate the performance of treatments to improve the durability of the surface
finishes. Optimal performance criteria for a treatment seeks to achieve the
following:
1) Reduce susceptibility of paint layers to abrasion and
biodeterioration
2) Not impact the color or matte lustre of the weathered
extant finish unless the intent is to restore the weathered appearance to its
original color (saturation)
3) reduce liquid water absorption, but not water vapor
transmission
4) Satisfy environmental and personal health and safety
standards
Due to the limited number of
original samples, this testing
program compared two types of treatments to provide Grand Teton
National Park with options now and in the future.
- Ethyl silicate consolidant (Prosoco OH100)
- Ethyl silicate modified with silane (Prosoco H100).
The samples were divided into
three cohorts
of six sample coupons each. All the samples were exposed to accelerated
weathering in a QUV Weatherometer.
Accelerated weathering is commonly employed
to test the performance of a treatment under extreme simulated weather
conditions. At intermittent stages during the testing program, the samples are
characterized in terms of their color (by qualitative and quantitative means), resistance
to abrasion, and hydrophobicity according to ASTM standards.
Based on the results of accelerated weathering and performance
testing, a series of possible applications will be suggested which balance
treatment potency with low aesthetic impact; these will be part of the outdoor
pilot tests applied to the structure in Summer 2019.
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