Something weird is going on in Washington D.C. and I’m not talking politics. It’s the big, white, marble dome on the Jefferson Memorial. The caretakers of that beautiful structure are flummoxed by what to do about the grungy, gooey mold-like gunk that has begun collecting on the dome, turning it from white to a dingy, dirty mess!


So far, experts have managed to give the yuck a name—biofilm—and determined that it’s a combo of algae, bacteria and fungi.

Here’s the problem: How to treat this icky stuff without damaging the soft marble of the Jefferson Memorial so that it remains safe for the environment and visitors alike.

When I read about this situation, of course I knew what to do. Of course! But I won’t be calling anytime soon to share my directive, which would include a helicopter with a huge sprayer and a thousand gallons of one of the most amazing products I’ve come across in a very long time. However, I am excited to share that with Ruby, who wrote:

Dear Mary: Awhile back you offered a method to remove moss and mold from a concrete patio. I misplaced that column. Could you mention that product one more time? Thank you, Ruby

Dear Ruby: Yes! You are referring to a wonderful new product on the market, Wet & Forget Moss Mold Mildew and Algae Stain Remover This outdoor stain remover like no other. It’s non-caustic, non-acidic, contains no bleach and safe on any outdoor surface. Even better, no scrubbing or rinsing required!

Simply spray it on and allow it to dry. Really bad stains may require multiple applications. The product comes concentrated—you mix it with water according to the label and then pour it into an ordinary pump-up garden sprayer for application.

Wet & Forget is not harmful to plants, however you will want to keep your pets away from the area treated until the product has fully dried.

Wet & Forget can be used on any outdoor surface including asphalt (black top), Astroturf, aluminum siding, awnings, brick pavers, composite decking, concrete, driveways, docks, fiberglass boats, fiberglass shingles, fiberglass hulls/topsides, green houses, gutters, inflatable dinghies, limestone, marble, marinas, natural stone, outdoor furniture, outdoor planters, paint surfaces, patios, patio furniture, plastic houses, recreational vehicles, retaining walls, sails, sandstone, shade sails, sidewalks, stucco, tennis courts, teak decks, textured finishes, tiles, tombstones, umbrellas (outdoor), vinyl siding, wood—and I believe, big white marble domes!

Wet & Forget is available at Amazon, about $37 for one gallon, which makes 6 gallons of ready-to-use product. Or if you prefer, some Home Depot, Walmart, Lowe’s and Ace Hardware stores carry Wet & Forget in store.

By the way, you don’t have to worry about ever misplacing a column again—even those that do not show up in your newspaper because I have them all organized and filed for you at Once you get there look for the search box at the upper right. Use that to type in a keyword or two for what you’re looking for. Be patient once you press “enter” because the search engine has to look through thousands of posts. I think you’ll be amazed.

Dear Mary: I made up a batch of your Magic Scum and Soap Cleaner, and sprayed it on my fiberglass tub. It worked like a charm, but when my husband found out that I used a homemade product on our expensive tub, he was not happy. He asked me how I knew it was safe to use on the tub since there is no way to knowing because it is homemade. I tried to convince him that vinegar and soap are pretty innocuous. Any way you can convince him that is safe to use? Would appreciate any advice you give me to convince him. Thanks. Vicky

Dear Vicky: I have been using this on fiberglass for many years, and I’ve recommended it to hundreds of thousands of readers as well. In nearly 26 years I have received untold responses from people who have used it on every type of tub, shower, tile, and other similar bathroom finished that are not natural stone—all to rave reviews. Never once has anyone ever reported that it caused damage or even the slightest problem. Several people have complained that the fumes from the vinegar were off putting and made them want to cover their faces, but so far that’s it (I’ve never found this to be a problem, but I know that some folks are more sensitive than others).

In an effort to bring your husband peace of mind, I visited several fiberglass tub and shower manufacturer websites. I perused the owner manuals of new fiberglass bathroom tubs, showers and sinks. Under “care and maintenance”, over and again the manufacturers recommend cleaning with vinegar and water.

My research on blue Dawn has not turned up any cautions that it might damage fiberglass or any other finish, for that matter.

I suggest you share this information with your husband. However, if his mind is made up, it is not likely to do any good. And that would be a shame because whatever product he insists that you use is likely to be expensive—and not nearly as effective, cheap and easy to use.

I wish you well and will keep my fingers crossed.

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