Points in Focus Photography

DIY Scrim

4+

What is a scrim and why should you have one?

Simple put a scrim is a sheet of diffusing material stretched over a frame. Simple enough; however, it’s one of the most versatile light modifiers you can have. Better yet, when it comes to bang for your buck, you can build one for less than $20 and about 30 minutes.

Scrim Material

Good scrim material should be translucent fabric or plastic that is of a uniform density. Commercial scrims typically use lightweight white rip-stop nylon or some similar material. Rip-stop Nylon can be had from most fabric stores in 58-60” widths and as long as you need, though compared to other options at $5-10 per yard, it’s not the cheapest solution.

A cheaper alternative, at least if the scrim needn’t be larger than about 70×70 inches is a while shower curtain liner. A 70×70 inch white shower curtain liner can be had for $5-10 depending on where you buy it, which is big enough for most DIY scrim needs.

The largest shower curtain liners I’ve been able to find are 108-inches wide. It’s also should be possible to get 108-inch width bolts of rip-stop nylon some places (though I’ve not haven’t had any luck or need for it yet). A 108-inch wide bolt of rip-stop would give you the ability to build a scrim 9-feet by however long you needed. However for a scrim that size, neither the 3/4-inch PVC used here or the simple design will likely work.

The Frame

Parts List

  • 2-3          10 foot stick of 3/4 inch schedule 40 PVC pipes
  • 1             10 foot stick of 3/4” class 200 PVC pipe (clips)
  • 6-            3/4 inch 90° elbows
  • 2-            3/4 inch Tees
  • 2-            3/4 inch couplings

Tools & Materials

Design

The overall dimensions for the scrim frame are set by the size of the material available minus 2 inches for clipping area. For example, a 70 x 70 inch shower curtain liner would limit the frame size to 68 x 68 inches.

The overall frame design with dimensions needed to cut the main tubes is shown below. All 4 tubes that make up matching sides are cut to the same length.

The dimensions W and H are 2 inches smaller than the scrim material used. Following the example of a 70×70 inch fabric, the 68×68 inch frame would have the top and bottom pipes cut to 32-1/2 inches, and the left and right pipes cut to 33 inches.

I partially glued my scrim frame together in order to reduce the risk of losing pieces and to add some rigidity. The diagram below shows how I glued my frame together. The couplings on the side rails allow the overall collapsed length to be kept under 3 feet.

If instead, you elect to use a single pipe for the sides, you’ll want to follow the alternative gluing plan show below. In all cases, aligning multiple elbows on the same pipe section should be avoided due to the difficulty of doing so before the PVC cement permanently bonds the parts.

The final two pieces are the “stand adapters”. These fit into the Tees on the short side and add two bits of functionality.

When the long end is fitted to the Tee, the stand will largely stand on its own. There are of course some limitations, both with respect to the maximum size scrim that can be supported this way (I’ve only tested up to 3 by 5 foot scrims with this system) also it won’t do so well in really windy environments.

The second method is when the short end is fitted to the Tees. In this configuration, with one “stand adapter” on each tee, the long pipes can be slipped over the top of a pair of light stands allowing the scrim to act as a suspended shade.

Scrim Clips

There are a number of ways to attach the scrim material to the frame, the two best solutions are either sewing pockets into the corners of the scrim material or using clips. I choose clips since it involved the least sewing work and I wouldn’t have to go looking for more material. The clips are made from ~2” lengths of class 200 PVC pipe that have had about 1/4 of them cut out.

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