Project 2- shower growth

Suspicious black growth is appearing in my shower/tub/sink caulk!


Mold Solutions Group

Do not despair. This happens to the best of us. It is not uncommon to find a black moldy something growing in your shower/tub/sink sealant. As time goes by, sealants will shrink and crack leaving room for water to get behind the sealant and just sit there. This water, along with other debris that gets in as well, is the perfect environment for mold. You may have tried cleaning these areas several times with limited results. Reality is, you may just be feeding the problem! Here is how you get rid of that pesky growth in your sealant…for the time being. Unfortunately, bathrooms and kitchen sinks are considered wet areas and even with all of the strides made in today’s modern sealants you may be doing this again someday. But, at least you are now informed about what leads to this problem.


  • First of all, safety! See above for proper PPE requirements. Always read the label of products before use.
  • You will need to remove the sealant in the affected areas. Be gentle! The areas around the sealant have a tendency to get marred up if you just go in there like a bull in a china shop scraping it out with just anything. If you can, use a tool that is made of hard plastic. This will help to minimize damage to surrounding areas. If you don’t have anything made of hard plastic, you can use a scraper with a razor blade but be careful. Don’t get in the way of that blade!
  • Have patience! This will not just magically happen. Removing sealants is a huge pain. By nature, they are designed to stick to the surface applied to. Even though the sealant may be failing in some places, it is not in most. Take your time and do a thorough job. The cleaner you get it, the better the new sealant will perform.
  • Once the sealant is removed, clean the exposed area well. Once again, if growth is still visible, use a fungicide designed to kill any mold that remains.
  • Let dry. Sealant will not perform well if applied to a wet surface. Plus, if you leave it wet, the problem will come back asap.
  • Use a quality sealant that is designed for the task at hand. If you have questions, ask your friendly hardware store employee for help in choosing the correct product. Always read the label on the product. There is important information there!
  • Have a wet rag handy. This is for wiping your fingers or wiping off any excess that gets into unwanted areas. Keep in mind that most sealants used in showers and on sinks will have silicone in them…which is not water soluble. You may want to have a cleaner designed to deal with this ready for use as well.
  • During the application, be careful to not go overboard with the amount of sealant you apply. You will thank us for this later.
  • If it is a larger area, do not apply sealant to the entire thing. Only apply enough in a workable area that will allow you to “fine tune” your application. “Fine tuning” involves you taking your finger and smoothing the recently applied sealant, then wiping the excess that comes off onto the rag we told you about. If you do too large of an area, the sealant may dry enough to where you can no longer manipulate it and then you will have an ugly mess. Work smaller areas.
  • Once you have completed the sealant application, read your label to find out when it is ready to get wet again.

Sometimes failing sealant can lead to larger issues. If your shower, tub or sink has been leaking for a long time, you may have wood rot and possible hidden growth behind your wall or between your flooring (hardwood, tile or linoleum) and sub-floor. It’s best to address these problems asap before the project is over your head!