A Practical Guide to Ready Mix Plaster for Modern Construction By The Guardian – Chief Technical Advisor, GUGAFIX® Construction Chemicals Plastering looks simple. Cement. Sand. Water. Apply it to the wall. But anyone who has managed a construction site knows that achieving consistent plaster quality is not always that simple. The quality of conventional plaster can vary because of changes in sand grading, cement proportion, water addition, mixing method, workmanship and site