Anyone with long hair is generally seen around town with hair ties worn as a bracelet. I keep many in my studio even to hold back wardrobe pieces that are not form fitting. While the best option is always to remember to have your client remove them before you start shooting, there is always that small chance you forget and it isn't seen until a few frames into the session.
After 10 years of photography, there have been a small handful of times that a hair tie makes it into a shot. Most of the time the client removes it and we start again. However, there is always that chance the shot you took might be a favorite and you do not want to lose it. Removing it can take less than a minute and save the shot.
The client's gaze was intense and I did not want to lose this image below. Frequency separation is always the top choice if you are comfortable with the technique.
If you do not feel frequency separation is right for you at the time, a few other tools can do the trick and in a short amount of time as well. The spot removal tool is normally a great way to remove distractions if they are small. In this case, it became too destructive to her arm.
An alternative to the spot removal tool is the patch tool. Select a wider range around the tie to create a smoother blend. If you chose the patch option, you can add the clone tool to the sides. In some cases the patch tool when moved from her skin to the couch will bleed a portion of the colors. The clone tool is a perfect fit for the sides. Make sure to use a thin brush to get in tight to the sides of the wrist. The first image is use of the patch and the second shows the clone.
After choosing which tool works best in your image, make sure to blend with a light opacity brush using the skin tone on her arm. Lowering the opacity will help make the transition more natural and not overly smooth.
So while the best option is to always run through a quick check on those ties, these are just a few simple techniques if you run into this situation.