The term scrim has two separate meanings in terms of fabric. In each case, it refers to woven material, one a finely woven lightweight fabric widely used in theatre, the other a heavy, coarse woven material used for reinforcement in both building and canvasmaking.
Light gauzy material 
A scrim or gauze is a very light textile made from cotton, or sometimes flax. Its light weight and translucence means it is often used for making curtains. The fabric can also be used for bookbinding and upholstery.
Scrims have also seen extensive use in theatre. The variety used for special effects is properly called sharkstooth scrim. However, in theater a scrim can refer to any such thin screen, and is made out of a wide variety of materials. Scrim has a rectangular weave that is similar in size in its openings to a window screen.
Another type of scrim is called bobbinet/bobbinette. This material has a hexagonal hole shape and comes in a variety of hole sizes. It is used for a number of lighting effects in the film and theatre industries.
Scrim is also used in clothing, usually covering the face or head. This allows the wearer to see out, while preventing others from seeing in. This may also be combined with camouflage to completely hide a person, such as a sniper.
A scrim was also an integral part of the Beijing Olympic Stadium in Beijing. It was the screen running around the top of the stadium during the opening ceremonies on which all kinds of scenes were projected. Li Ning also ran around it just before the cauldron lighting.
A scrim (also called a screen) is used as an acoustically transparent covering for a loudspeaker to protect the diaphragm and dust cap, or as an air filter element to protect the voice coil and other components of the motor.
Applications to stage lighting 
Scrims both reflect and transmit light. This means that if a light from a front-of-house position is shone at a scrim, then both the scrim and everything behind it will be lit. This can lead to a variety of interesting effects:
- A scrim will appear entirely opaque if everything behind it is unlit and the scrim itself is grazed by light from the sides or from above.
- A scrim will appear nearly transparent if a scene behind it is lit, but there is no light on the scrim.
- A dreamy or foggy look can be achieved by lighting a scene entirely behind a scrim.
- If a light with a gobo is aimed at a scrim, the image will appear on the scrim, but also any objects behind the scrim will be lit by the pattern as well.
In general, anything that is lit will be seen on both sides of a scrim: scrims do not absorb light. Scrim can also be used in theatre in combination with a cyclorama or backdrop. The idea is similar to the other uses. When the drop is lit (or images or video are rear-projected onto the back of the drop), the images or colours projected are visible. However when the drop is not lit, the images or colours will disappear. A scrim can also help dull the image, creating a greater sense of depth.
Another effect is caused by layering two scrims, or even by placing a mirror behind a scrim and lighting it: the familiar moire effect. This can often cause audience disorientation.
Reinforcement material 
The technique of scrim as a reinforcement is commonly applied in the manufacture of glass fiber or carbon fiber composites, scrim layers may be used on the exterior surface of the carbon fiber laminate for an improved protective surface.
A similar usage of the term is found in sailcloth manufacture, where scrim is a strong loose weave of fibres laminated into the cloth to provide extra strength and stability to sails.
In carpentry, scrim is the name given to a very heavy, coarsely-woven fabric similar to hessian or coarse canvas, which is stretched over interior boards to provide support for wallpaper and add an extra rigidity. This method of construction, widely used in older houses, is often referred to as "scrim and sarking", the sarking being the board.
Scrim is also an item that utilizes plies of tissue reinforced with a layer of nylon (much like fishing line or heavy duty monofilament) or cotton thread. 2-ply tissue 1-ply scrim the layer of scrim is not counted in the ply count. 2/1 would be a 2-ply scrim.
Scrim is a glass fibre (previously burlap) open mesh tape used to cover the joint in plasterboard/wall board prior to plastering. It prevents a crack appearing in the plaster finish at a later date. The roll of tape may be plain or adhesive coated to facilitate its installation.