Step 3: The Cleanup
After you have dusted the entire surface of the mattress with bicarbonate of soda, leave the mattress for several hours (a whole day if possible) for the soda to work it's magic.
The soda draws dirt, moisture and odours out of the fabric and absorbs them leaving the material unblemished.
After the mattress has been left to settle, use the vacuum cleaner to suck up all of the soda from the surface and inside the mattress. Do this quite thoroughly otherwise you'll get puffs of soda everytime you lie down.