| 摘要 |
The present invention relates to novel compositions, which provide an indicator for location and/or concentration of the composition during application. In a preferred embodiment, the indicator is a compound that is visible at a first pH and invisible at a second pH. The composition includes the indicator and a volatile base or acid. The volatile base or acid enables the composition to be at a first pH so that the indicator is visible when first applied to a desired surface. However, upon evaporation or degradation of the volatile acid or base, the composition will be at a second pH, causing the indicator to disappear.
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