In fact, it is not difficult to handle the situation when the white shower door rubber seal strip goes musty and black.

When facing such a tricky situation, a rag of the normal size does not work as we have to fold the rag into several layers before wiping the strip clean. Actually, you can use a toothbrush to clean it. Given the size of a toothbrush, it is quite suitable for cleaning some small parts.

Prepare a used toothbrush moistened with diluted bleach and brush gently the rubber seal strip and the narrow gaps. As a result, stains can be removed without a hard scrub.

If the musty situation is way worse than expected, try this method a few times more and the effect will be noticeable. Once the rubber seal strip gets dirty, use a cotton swab moistened with ethanol for disinfection to remove the stains, even the ones in the gaps! After that, wring out the cloth soaked in hot water and use it to wipe away the remaining stains. Overall, a very simple method of cleaning it is!