Meek Cleaner vs. Chemical Beast
Rydlyme proves eco-friendly but slow, while caustic MaryKate cleans fast.
In the November 2007 issue, we reviewed a big batch of waterline stain removers/hull cleaners. Spray Nine’s gel got the nod over the 21 other products, but there were a number of Excellent results—and that’s because these acid-based cleaners don’t mess around. One of the most aggressive cleaners out there is the MaryKate On&Off, which received an Excellent rating and was a Recommended product. Made by CRC Industries, it is a caustic stew of acids, mostly hydrochloric (20 to 25 percent by weight) and phosphoric (5 to 10 percent), with a bit of oxalic (1 to 5 percent). We’ve used it often, with good results, but it only would be considered pleasant if you’re nostalgic for World War I trench warfare. Even outside in a breeze, it stings the eyes, nose, and breathing passages. If you work without a respirator—not recommended, but sometimes done—you need to hold your breath when in range of the fumes, and take new breaths upwind. (It’s best to wear a respirator, rubber gloves, and eye protection.)