My husband recently had knee surgery and we have a CPM machine on our fabric couch, which moves his knee for him. We happened to move the machine today and noticed that two screws have put rust all along the upholstery. How can we remove the rust without ruining the couch (which is less than a year old)?
Your situation is much more problematic than the usual rust-stain-on-fabric question because your fabric is upholstered onto a couch. This makes rinsing any treatment off the fabric much more difficult. First, I will go over how you would deal with a rust stain on fabric you can wash in a clothes washer.
Rust stains are particularly limited in what will effectively take them out. Most importantly, it’s critical to note that rust stains can NOT be removed with Clorox® Regular Bleach2 (or any chlorine bleach for that matter). You need to use a rust remover product instead, which can be found at hardware stores. These products are very strong acids—that’s why they are effective—you need to be sure to read and follow the package directions, including wearing gloves. The biggest issue with treating machine washable fabrics with a rust remover is whether or not they are colorfast. You can always test a spot on a hidden part of the stained items if you want to be sure the rust remover is safe to use—again, follow the instructions on the package. After you have treated an item, be sure to rinse it thoroughly and let it air dry.
For your upholstered couch, somewhere on the couch (usually under the cushions) there should be some care instructions—make sure you read these first to understand what the manufacturer recommends for care. Hopefully a rust remover as described above could be appropriate as long as it is safe for the fabric and it can be completely rinsed from the fabric. You should always test the rust remover for safe use; it’s the thorough rinsing that’s the biggest challenge. Even if you rent an upholstery steam cleaner, you may not be able to tell how thoroughly you’ve extracted the treatment, and time goes by and your couch discolors. You could bring in a professional, who may have enough experience to know when it’s likely something is thoroughly rinsed, and they should have an appropriate (acidic) pretreater. If you decide you have nothing to lose (the couch is already damaged) and try it yourself, you also need to make sure the couch thoroughly dries; a portable dehumidifier can speed this up.
I didn’t ask whether or not the stains are on the cushions, and not the body of the couch. If that’s the case and the cushion covers are removable, then you could try spot treating the rust stains (as directed on the rust remover product package) and rinsing them as you would a garment. Note that whenever you wash cushion covers, you need to put the covers back on the foam inserts while the fabric is still damp. If you wait until the fabric is all the way dry, then the covers won’t fit because of relaxation shrinkage that happens naturally during washing and drying. Putting the covers on while the fabric is damp allows you to gently stretch the covers to fit and zip them closed. Lean them up so they can easily air dry!
This is definitely a challenging problem without an easy guarantee of success because upholstery is so different than machine washable fabric and rust stains are very limited in what treatment actually works. Those reasons may be enough to choose to work with a professional upholstery cleaner. I hope you can restore your couch successfully—good luck!