Which method of specifying plaster provides exact materials and mix proportions?

The method of specifying plaster that provides exact materials and mix proportions is the descriptive specification. This approach includes detailed information on the specific materials to be used, their quantities, and the exact mixing proportions required for the plaster. By providing such precise details, the descriptive specification ensures that the contractor knows exactly what materials and methods are expected to achieve the desired quality and performance in the plaster application.

This specificity helps to reduce ambiguity in the construction process, allowing for consistency in the finished product and reducing the risk of variations or misunderstandings during implementation. It is particularly important in cases where certain performance characteristics, aesthetics, or durability are critical to the success of the project.

In contrast, other methods like proprietary specifications emphasize a particular product or brand without detailing the materials and mix ratios, while performance specifications focus on the end results without prescribing specific materials or methods. Nonrestrictive specifications allow for more flexibility, potentially leading to variations in materials and results.