Foam Selection for Upholstery: What You Need to Know

Cushions are tricky business. “Comfortable” is endlessly subjective, and the margin of error is alarmingly small, considering that foam and fabric are notoriously imprecise

I wouldn’t presume to answer all your questions in one post, but I WOULD like to offer some basic product information to make your job a bit easier.

Let’s talk about foam.

There are so many ways to fill a cushion – springs, cotton, down . . . Personally, I’m a foam girl – it’s relatively easy to work with – versatile and cooperative. My local supplier, Fabric Supply Incorporated, offers a wide, high-quality selection, so I’m able to give clients great options and information.

But. But, but, but.

If you’re going to work with foam, you need to make informed decisions.

You need to understand THE NUMBERS.

Labeling and verbiage will vary from supplier to supplier, and many try to simplify the information with subjective labels like, “Ultra Comfort Deluxe”  but in order to compare foams, you need TWO numbers in particular:

FIRMNESS and DENSITY

Contrary to popular customer opinion, these are NOT the same thing.

FIRM is how hard a foam is.

DENSE is how heavy a foam is.

First, let’s talk about FIRMNESS

Firmness is expressed as an IFD (Indentation Force Deflection)

IFD is an expression of how many pounds of pressure it takes to compress any given foam from 4″ to 3″

The higher the IFD – the firmer the foam.

For example, an average seat cushion has an IFD around 30#. It would take 30 pounds of pressure to compress a 4″ sample down to 3″

This number works nicely in a thicker cushion, where people want an inch or two of give.

However, if a seat is 1-2″ thick (like on a dining chair) a higher IFD helps ensure that you don’t sit through to the board. Here, we might use an IFD of 45-65# so people only sink in a tiny bit.

Going the other way, back cushions generally need  a lower IFD.

Seats take all our weight, while backs receive only a fraction. So we want them to compress slightly with less force. An IFD of 30 that feels comfortable in a seat would seem extremely firm in a back – so we might choose an IFD of 20 or less.

How firm a foam feels also becomes relative when you consider who’s using it. A 90 pound grandmother sitting next to a 300 pound linebacker would clearly illustrate that optimal IFDs aren’t universal.

Likewise, consider how your sofa feels when you sit on it, versus when you lay down. Same weight, but spread over a much larger area, so the foam won’t compress as far. It FEELS firmer.

This makes it tricky to choose foam for things like campers, where the same foam may be used for seats AND backs, then convert into a bed. Little wonder they’re notoriously uncomfortable.

Fun, right??

Let’s not over complicate the issue too much. The bottom line is, IFD tells you how firm a foam is in relation to other foams. Don’t rely on meaningless, generic terms. Get those numbers and start using them.

Now let’s talk about DENSITY.

DENSITY is how heavy your foam is. It’s expressed as a weight per cubic foot.

DENSITY is your best indicator of longevity. It tells you how much product the foam contains (versus air). A good foam has more material crammed into the same cubic foot.

Density will range from about 1# to just over 3#.

THIS is the number you need to compare quality, and it is most closely associated with cost (in case nobody told you, good foam is pricey stuff)

As a rough guideline, a 1# foam can be expected to last about a year with regular, everyday use. (frankly, I think that estimate is optimistic)

A 3.1# foam (our favorite) is considered a 10-14 year foam, depending on who you ask.

You don’t need the densest foam for every application – lower density foams are often found in occasional use settings like  window seats and camper cushions.. There ARE times when it makes sense to spend less.

But for the sofa in your busy living room, a low density seat foam will disappoint in a hurry.

Shelf life on a foam will depend upon who’s sitting on it, how often and for how long. Cushions that get flipped and swapped will naturally last longer than odd shaped cushions that never get rotated (like the asymmetrical chaise on a sectional sofa)

The same foam will last much longer in a guest bedroom than it will in your favorite chair.

If the only “person” who ever sits on it is your toy poodle , a good cushion could basically last forever. If, however, you have three giant teenagers living, eating and wrestling on it every day .. .

Do you see what I’m getting at?

When we talk about “how long will a foam last” there are loads of variables . . . But density is your best tool for approximating an answer.

Now here’s where people often get tripped up:

FIRMNESS AND DENSITY ARE INDEPENDENT VARIABLES

A foam could be firm AND dense. But not as a rule.

A high-end bed topper, for example, can be very heavy yet very soft. It has a high density, but a low IFD  It starts soft, and stays soft, for a long time, without losing it’s cellular integrity (I.E. flattening out.)

My mattress has a 2″ topper. The density is 2.4# and the IFD is 18.

Heavy. Soft. Amazing.

Likewise, a very light foam, COULD be very firm. While it wouldn’t hold up under intense use, it might have a time and place. We sometimes sold it for small, elderly dogs who needed a ramp to get on the bed. True story.

Unfortunately, thinking you bought a dense foam, when you really bought a firm foam, THAT’s a bummer. Starts firm. Fails fast.

Unknowing consumers, disappointed with cheap, cushions, often think that the answer is a firmer foam. But if their new foam has a low density, it ends up being a short fix.

If this is all new information, your brain is probably cooked by now. Hang in there. Bookmark this page and keep coming back. And here’s a cheat sheet to use while you’re learning – these are the handful of foams we regularly stock and use in our own workshop and classroom:

A few additional notes:

• these numbers are from our preferred vendor, Fabric Supply, Inc. They are a wholesale, to-the-trade vendor, so you need to have a business account set up to purchase. If you’re a serious hobbyist, still exploring, check out our new online marketplace for some of our favorite foams ready to ship.
• H.R. Means “High-Resiliency” and it matters. Without getting into all the nitty gritty, it’s better quality materials which means improved handling and increased longevity. Wherever you’re purchasing, ask for numbers, and ask for H.R.
• One of the best ways to understand foam is to get your hands on it. If you attend a workshop in St. Paul, feel free to ask an instructor about our classroom samples.

Okay, that’s the longest I’ve ever written about foam, and I’m ready to stick toothpicks under my toenails.

If you prefer to see this information presented in video form, check out this YouTube video we made a few years ago with The Workroom Channel

And if you’re here from the Aunt Bea tutorials on our own YouTube, here are additional links for tools and products we used (Please note that you must have an account with Fabric Supply in order to purchase from them)

TOOLS/SUPPLIES:

FLC Marketplace

• Acu-Cutter Electric Foam Saw
• Sprayway Silicone Spray  (For spraying the saw blade)
• FSI Heavy Duty Spray Adhesive (For gluing batting to foam)

Fabric Supply Inc

• Dacron – Bonded Polyester 3/4oz (standard batting for seat cushion and first layer of back cushion)
• Dac 91 (premium wrap for back cushion)
• HR-18 (back cushion foam. Density 2.4# IFD 18)
• HR 3133 (seat cushion foam. Density 3.1# IFD 33)

Cynthia 🙂