What method can be used to reduce a sample to testing size before a wash according to D1140?

The method that is appropriate for reducing a sample to a testing size before a wash, according to D1140, is the use of quartering or a splitter. This technique is designed to ensure that the sample retains its representativeness while being reduced in size for further testing. Quartering allows for the sample to be divided into smaller portions, and by consistently taking a quarter of the sample, you can minimize the risk of losing important characteristics that might affect test results.

In D1140, maintaining sample integrity is crucial, especially prior to washing, as washing can alter the composition of the sample if not handled correctly. Quartering is a widely accepted practice in soil testing that ensures an accurate representation of the original sample.

Other methods, such as cutting the sample lengthwise, drying and grinding, or freezing, can disrupt the material's properties or alter its water content and particle size distribution, which are vital for accurate results in subsequent testing. Therefore, quartering or the use of a splitter stands out as the most effective and appropriate method for sample reduction in this context.