Plasterers scrim is used to reinforce the body of a plasterers work to prevent cracking. Traditionally jute, canvas, hessian or flax were used made in differing widths depending upon requirements e.g.; restoration, jointing plasterboards or matching works.
When plasterboards became popular thinner cotton scrim was used to joint boards as finishing coats were applied, this being a cheaper alternative to the previous types of scrim – the downside being that if the boards were not secured correctly the cotton scrim would crack.
Cotton scrim has largely been replaced by a man-made self adhesive polyester-type scrim with a vinyl covering. This material is strong, easy to use and very cost effective.
Traditional scrim materials are still used in fibrous plaster work. In more recent times glass reinforced gypsum (GRG) has been a system of plasterwork used where fibreglass matting or strands are placed into the body of an alpha-grade plaster, the fibreglass acting as a reinforcement in this product.
In summary scrim is a flexible gauze, fabric or fibre type material used to prevent cracking in plasterwork.
Lengths of traditional scrim are also used in multiples, soaked in strong plaster, these being knows as ‘wads’ to help fix and support bench made plaster casts. These wads are very strong and often employed with steel wires for a method of fixing knows as ‘wire and wadding’.