While it might be tempting to use your comfortable indoor cushions on outdoor furniture, this is generally not recommended and can lead to several problems. Indoor cushions are not designed to withstand the outdoor elements. They lack the specialized materials and construction needed for durability outside.
The primary issue is moisture. Regular rain or even heavy dew can quickly soak into indoor fabrics and filling. This not only makes them uncomfortable to sit on but creates a perfect environment for mold and mildew to grow, which can be difficult or impossible to remove. Furthermore, the filling materials, like cotton or down, will clump and lose their shape when wet, ruining the cushion's comfort and appearance.
Sun exposure is another major concern. The sun's powerful UV rays will cause the colors of indoor fabrics to fade rapidly, making them look old and worn in a very short time. The fabric itself can also become brittle and tear easily after prolonged sun exposure.
Finally, indoor cushions are not built to resist pests. They can attract dust mites, and in some areas, even become a nesting material for insects.
For these reasons, it is always best to use cushions specifically designed for outdoor use. Outdoor cushions are made from solution-dyed acrylics, polyester, or other synthetic fabrics that are water-resistant, mold-resistant, and UV-protected. Their fillings are typically quick-drying foam or fiber. While investing in proper outdoor cushions may cost more initially, it will save you money and frustration in the long run by lasting for multiple seasons. If you must use an indoor cushion outside temporarily, be sure to bring it in immediately after use and never leave it exposed to rain or overnight moisture.