Colorado State’s Master Gardener program has a guide for estimating soil texture in a variety of ways. One of those ways is a jar method on the last page of the guide. By mixing soil, water, and powdered dish detergent in the jar, then allowing it to sit for two days, and marking the settled level of material at one minute, two hours, and 48 hours, the sand, silt, and clay fractions of the soil can be calculated. Below is an image of the last page describing this jar method.
