My research for this column was fascinating. I talked with two caulk scientists. I found out that caulks contain mildewcides and fungicides. These chemicals happen to be water soluble. This means that water can dissolve them.
I also found out that even though caulk appears smooth to the naked eye, it is actually a somewhat porous surface where mildew spores can readily hide. Couple this with the fact that many body soaps contain ingredients that are food for mildew and you often have lots of water where you have caulk and you end up with perfect growth and survival conditions for mildew.
Caulks that mildew quickly contain small amounts of the mildewcides. Mildew-proof caulks contain lots of these chemicals. The intention is to add enough mildewcide such that it takes years for it to completely wash away from the caulk. The manufacturers hope that it is time to re-caulk before the caulk actually begins to turn black. I don't have any problems with that thought process!
Getting Caulk to Stick
Caulks are basically a first cousin to adhesives. Caulk, adhesive and paint chemistry is very similar. Stop and think. All three things basically 'stick' to something. If you want caulk to be waterproof, you need to make sure that the surfaces to be caulked are clean. They need to be dry.
It is usually not a problem to get caulk to stick to a crack. If a caulked joint does fail, the trouble can often be traced to dirt or dust that was not removed prior to the application of the caulk. Take time out and always clean the areas to be caulked.
If you visit a large home center or a major paint or hardware store with a good caulk department, you will often find caulk removers. These products work well if you follow instructions.
Often the largest hurdle is removing as much of the caulk as possible - with a razor or some other tool. The more caulk you can scrape away before applying the remover the better off you are.
You can often find caulk removers for each type of caulk. However, the tougher the caulk - like silicones - the harder they are to remove. One of my readers wrote to me just before this bulletin was written - a woman from Michigan. She reported to me that she had great success with a silicone caulk remover made by the 3M Corporation. I have not used it so I can't tell you what I think about it. The Michigan reader told me that she used it to "...get silicone caulk off our fiberglass trailer and it worked GREAT!" She convinced me!
Preventing Mildew in Baths
An ounce of prevention is worth a pound of cure it is said. This is true in bathrooms with respect to the war on mildew. You can reduce mildew growth in tubs and showers if you try the following things:
Keep the tub and shower surfaces clean. This means that you should wash them once or twice a month, not once or twice a year! The soap and body oils that come off of you are mildew food!
Consider using a squeegee in the tub or shower. Just after you turn off the water and before you jump from the bathing area, use it to remove 90 percent of the water from the tub and shower area. This water will go down the drain instead of evaporating into the air during the rest of the day. High moisture air content within the bathroom helps the mildew to live.
Leave the shower door or curtain OPEN after you leave the bathroom. Also leave the bath door open so that air flow can readily dry tub and shower surfaces. You want the mildew to die of thirst!