How to Choose an Outdoor Foam
We get lots of questions from customers asking what is the perfect foam for their outdoor application that will last for years in the sun, rain, saltwater and more. The truth is, there is no perfect foam. Every foam type has its pros and cons. The best you can do is choose a foam that meets most of your criteria with the understanding that the foam might need to be replaced after several years (depending on your choice of cushion fabric, your climate, and whether you cover your cushions or bring them out of the elements). We're going to discuss the qualities of each of our outdoor foams to help you make an informed decision for your cushion or seating project.
Types of Outdoor Foam
Dry Fast Foam
Dry Fast foam is also known as reticulated foam. This open cell foam has open pores that promote airflow and excellent water drainage abilities. Water passes right through the foam without being absorbed. This foam dries out quickly and is antimicrobial, making it an excellent choice for outdoor cushions, especially when paired with an equally water draining fabric such as a vinyl mesh.
If the sun gets to the foam through your cushion fabric, then the foam will start to break down. So, although a vinyl mesh cushion cover is great for water drainage, it pays the price for foam longevity. Dry Fast has a maximum density by design, so it can never achieve "high density" classification. This is the reason we label it an "occasional use" foam throughout our website and we don't recommend it for high-traffic, everyday applications.
But if you need quick-drying foam, Dry Fast is the only way to go. Its uses don't end at outdoor cushions. Dry Fast is also used for mattresses and sleeping pads in boat cabins, RVs, tents and camping. The foam's highly breathable nature and superior airflow make it a favorite in the marine, RV and camping markets. If the foam gets dirty, it's easy to hose off and dries in no time. Dry Fast foam has several very useful applications, just take into consideration where you put the foam and how much sunlight it could be exposed to.
Closed Cell Foam
Closed Cell foam is probably the long term standard for outdoor boat seating. This foam is designed for flotation purposes and is especially useful for sailboat cockpit cushions and bosun's chairs. When used for cockpit cushions, it is typically covered with an outdoor canvas fabric, such as Sunbrella® Marine Grade. We do not recommend pairing Closed Cell foam with vinyl mesh cushion material as the foam will start to break down with sun exposure.
The big downfall of this foam is that it's the most uncomfortable to sit on. It's three times as firm as polyurethane foam and is stiff and unforgiving. However, this can be a huge benefit for cockpit cushions. When climbing in and out of a boat, you want a stiff cushion to step on so that you do not roll an ankle or lose your footing. The fact that your cushions can also double as flotation devices is another asset. It dries, shrinks and cracks in the sun, but you won't see that since the foam is always covered with a solid canvas fabric. Closed Cell foam has its purpose, though a limited one. It is not an all-around foam choice.
High Density Foam
Until recently, you could not get an antimicrobial version of High Density Polyurethane Foam. We now offer an antimicrobial version, but only in "firm" firmness. High Density polyurethane is the only true "frequent use" foam on the market. It is intended for heavy-use, everyday seating applications and can last up to 12 years with proper care and maintenance.
This is great for inside a boat for salon cushions and mattresses. If using this foam outside, be very careful because if it gets wet it will swell up like a sponge. There are ways to avoid this, such as covering High Density foam with a waterproof vinyl. You can also wrap the foam in a layer of Cushion Wrap Silk Film (#103933) to add a level of water protection. You either need to pair the silk film with a breathable canvas fabric or add vent grommets to a vinyl cushion to allow air to escape when sitting on the cushion.
Vinyl is a popular choice for powerboat and pontoon seating, especially when using it for applications where the vinyl is stapled to a backer board. With a backer board, there are no sewn seams where water can seep in. Again, the biggest risk with polyurethane foam is the foam getting wet and not drying out. Then you get mold and mildew, unless you choose the antimicrobial version.
Since there's a risk of water seeping in and damaging the foam, most powerboaters and pontoon owners are vigilant about covering their cushions with additional protective covers. Sailors don't typically cover their cockpit and exterior cushions. They just leave the cushions out in the elements. As a result, we don't recommend polyurethane foam — either High Density or Medium Density — for exterior sailboat cushions.
Medium Density Foam
Medium Density Polyurethane Antimicrobial Foam is the standard foam choice for the marine industry and for boat interiors. It was the first foam to have antimicrobial properties added. All of the Medium Density foam we sell at Sailrite is antimicrobial. We still consider this an "occasional use" foam since it is not as dense as High Density. It is less expensive but doesn't last as long as High Density polyurethane. Medium Density is what most boat manufacturers use inside boats today.
This foam has the same disadvantages as High Density, given that they are both polyurethane foams. Medium Density polyurethane will soak up water and is not naturally water draining like Dry Fast. If using Medium Density polyurethane outside, you can wrap it in a layer of Cushion Wrap Silk Film to protect the foam from getting wet and use a water-resistant outdoor upholstery fabric.
Ways to Make Your Foam Last Longer
Regardless of which foam you choose for your application it won't last forever, and that shouldn't be something you expect from foam. None of the foams mentioned above are "perfect" for outdoor cushions because, as you've learned, there is no such thing as a perfect foam. You have to make a decision based on the information presented and which foam qualities best fit your use. Just know that you might have to replace your foam sooner than you expected depending on where you put it, how often it's used, and the type of fabric covering you choose.
But there is something you can do to extend the life of your foam. Here are our easy tips on how to make your foam last as long as possible:
1. Use protective covers. It can't be said enough that covering outdoor furniture and exterior marine seating will extend both the life of the foam and cushion fabric.
2. Put the cushions away when not in use. If your outdoor seating area is seasonal, bring your cushions inside or out of the elements to extend their life.
3. Protect the foam from the sun and elements as much as possible. So, consider not using vinyl mesh fabric. But keep in mind that mesh is the best way not to sit on wet cushions when paired with Dry Fast foam. This is a dilemma you will have to consider carefully and decide what's best for you — longevity over drainage, or drainage over longevity.
4. Use water-resistant and UV-resistant fabric for your cushions. But again, keep in mind that this is a compromise for comfort and possibly foam drainage capabilities if using Dry Fast foam.
Basically, foam life for all of the options listed above has as much to do with care taken and the covering fabric as it does with the foam itself. We have excellent resources to learn even more about foam. On the "How-To" section of our website, click the "Selection Guides" tab. From there, scroll down and select "Foam Selection" under "Buying Guides." These blogs will tell you everything you need to know about foam qualities and uses, as well as how to pair various foams with the right fabric and notions to create long-lasting cushions.