Drying backpacks and other outdoor gear is a regular chore and I thought I would share a couple techniques that have helped me a great deal.
If I wash a pack or other coated gear, I am careful to limit wet time to protect the coatings. Avoid saturating the fabric and coatings as much as possible. Other than a quick rinse, I only wash the interior when it it has food or sticky goo inside. I use the least aggressive cleaner possible, starting with a gentle plain water rinse with a sink sprayer, then graduating to a “technical” wash like Nikwax Tech Wash or Atsko Sport Wash and only using detergents when all else fails— and limiting that to spot cleaning. All washing is done by hand in lukewarm water, never hot. That helps preserve the water repellent treatment on the fabrics and the interior coatings. Scrubbing a saturated polyurethane coating is a perfect way to destroy it! Don’t go there.
I do think that a thorough rinse of the pack straps and back padding is a good thing. Those areas collect dust, sweat and body oils and promote deterioration. Just a rinse with cool water is no more invasive than a rain shower.
I hang my pack upside-down over my laundry tub to drip for bit and then give it a gentle wipe-down with an old beach towel that does not have fabric softener in it— which is also bad for water repellency. The towel drying allows me to get into the nooks and crannies that collect water and speeds drying time exponentially. Drying in the shade on a warm day is fine, but avoid full sun as ultraviolet is bad for the fabric and hardware.
After the towel drying, I hang the pack with all the pockets as open as possible to complete drying. I never use heat, but I do use an aquarium air pump to help get dry air into the deep pockets like the hydration compartment or the sleeve for the internal framesheet. The pump keeps the air circulating, bringing dry air in a pushing the saturated air out. I hang the pump next to the pack and run the hose into the area I want to dry. This trick is great for gloves and shoes too. I had a waterproof camera bag that was very difficult to dry and the pump trick worked great for that.
Hanging the pump helps reduce the hum it makes while running. I bought the pump in a thrift store for a couple dollars.