Julie might have used a valuable Beatles or Rolling Stones CD or two or three to make a backsplash in her home in Essex, UK.
Here's what she want to know:
"I have made a kitchen backsplash out of old CDs.
How can I remove the tile grout without scratching the CDs?
Are cup brushes any good?"
Here's my answer.
Julie, I'm assuming you're talking about the actual CD and not the plastic case. In either case, this advice should work.
I'd get a one-liter can of water-based CLEAR urethane and coat the CDs with three coats before you grout them. The urethane will protect the soft plastic.
You know urethane is durable because you can walk on it.
If the grouting process creates minor scratches, a final coat of urethane will make them disappear.
I would never use a cup brush for this project. It's too aggressive.