Foam Series: Anatomy of a Cushion
Have you ever wondered what goes inside a cushion cover? Is there more than just foam in there to make the cushion soft and plump? There is, and in this segment of our Foam Series, we’re going to talk all about those other additives that can be inside a cushion besides the foam. There are fill options that make a cushion look fluffier and wraps that act as moisture barriers for the foam.
If you cut a cushion in half, you’d most likely find a series of layers under the fabric stacked like a parfait. At the very core is the foam, which may be layered itself (see our post “Selecting the Right Upholstery Foam” (#300057XHT) to learn more about layering foam). On top of the foam there is usually a layer of batting, and then there might be a thin layer of silk film or another protective wrap. Not all foam options require extras like batting or a wrap and your cushion’s application often determines whether or not you’d want to use these extras at all.
Batting is standard in most types of cushions. Batting is what gives a cushion its rounded shape and plump puffiness. The batting goes right against the foam and is usually glued in place using a spray adhesive. Wrap the batting around the foam so both the top and bottom of the cushion are covered plus one side. If you choose, you can also wrap the batting so it completely encases the foam, folding the corners like wrapping paper.
While batting is standard in home and marine interior cushions, certain types of foam don’t need a batting wrap. For example, compressed polyester is already soft, so it can fly solo within a cushion without any extra batting. Closed cell foam is generally used without batting or wrapping as well because the batting would hinder the foam’s ability to float. Similarly, Dry Fast foam shouldn’t be wrapped in batting either, as the batting would prevent water from properly draining through the foam.
When you open up an old cushion you may find little fluffs of polyester fiberfill inside in addition to the foam and batting. We sometimes use this filling to help round out corners and other pockets within a cushion. Doing this is completely optional and just an aesthetic choice, but you will see us do this from time to time in our cushion videos.
Silk film is a noiseless, plastic moisture barrier that you can wrap around your foam to help with its moisture resistance. Silk film is wrapped around the batting and then left inside the cushion. This is especially good for applications where you might have had to trade moisture resistance of one particular foam in order to get more important properties in another. Silk film is a great idea inside outdoor living and marine interior cushions especially. We do not recommend using silk film around closed cell foam (it’s already moisture resistant) or Dry Fast foam as the silk film inhibits Dry Fast’s ability to drain water.
Silk film has another great bonus use. After wrapping your foam in the silk film you can vacuum the air out of the foam to shrink it to 70% its original size. This makes it much easier to stuff the foam into a fabric cover. You can learn more about how to do that in our “Using Silk Film to Shrink Foam” post (#300060XHT).
Spun-Bonded Pillow Protector Fabric
This fabric was designed for making custom pillow forms (hence the name) but since it’s a breathable, water-repellent material, it’s actually great as a wrap for foam and batting too. Similar to silk film, this spun-bonded fabric acts as a moisture barrier between the fabric and the foam. The same rules of thumb apply too — it’s not necessary to wrap closed cell or Dry Fast foam in a protector fabric.
To use this fabric barrier, sew a pillowcase of sorts for your foam, with one side open. Then, slide your foam with the batting attached, into the casing and sew the open end closed. Now your foam is safely protected inside your Spun-Bonded Protector Fabric.
When it comes to what’s inside your cushion, the choice is really up to you, but hopefully these guidelines will help you decide what will work best for you!
To learn more about foam be sure to read the other posts in our foam series, “5 Important Foam Terms to Know" (#300052XHT), “Comparing Types of Cushion Foam” (#300053XHT) and our foam selection posts.