Those Blue Spots on a Zinc Monument: My Loose Tablet Fix

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You know, I’ve been tending to graves at St. Mary’s cemetary for fifteen years now. Started right after I retired from teaching third grade. My husband, God rest him, thought I was losing my marbles—spending Saturdays scrubbing old stones. But there’s a peace to it. Anyway, about three years ago, I was wiping down a beautifull old zinc monument—the the one shaped like an open book for the Henderson family—and I noticed these funny blue-green spots. Looked like someone had dripped ink on it. Took me a while to figure out what they were. Turns out, those blue spots are a sign that the loose tablet—the zinc plate with the name and dates—is starting to corrode. Not rust, exactly. More like a chemical weeping. And if you don’t fix it, the whole inscription can get clouded or even flake off. So I got to experimenting. Tried a few things that didn’t work. Big mistake with a wire brush once—never again. But I finally found a method that’s gentle and works. Let me walk you through it.

What Are Those Blue Spots? The Science Bit (Short and Sweet)

Zinc monuments are a different beast from granite or marble. They’re made of a zinc alloy, often painted or coated. The blue spots are usually a buildup of zinc carbonate or zinc hydroxide—basically the metal reacting with moisture and air over decades. Sometimes it’s just surface staining. Other times it means the protective coating is failing. Think of it like a scab on a scraped knee. You don’t want to rip it off, but you do need to clean around it gently. The loose tablet—that’s the big flat section where the name is etched—is the part most prone to this. The blue spots mean the tablet is starting to get unstable. Ignore it, and you might lose the lettering.

What You’ll Need: My Own Little Kit

I keep a bucket with everything in my trunk. Here’s my list for zinc monument blue spots:

• A soft bristle brush. I use a horsehair brush, about 4 inches wide. Not a scrub brush from the kitchen—those nylon bristles are too harsh.
• Distilled water. Tap water has minerals that can leave their own spots.
• A pH-neutral, non-ionic cleaner. I swear by D/2 Biological Solution. It’s what the pros use. Smells a bit like seaweed, but it doesn’t hurt the zinc.
• A plastic spray bottle.
• A microfiber cloth. Old cotton t-shirt works too.
• Optional: a wooden popsicle stick for gentle scraping if there’s loose paint.

That’s it. No bleach, no vinegar, no harsh household chemicals. Those can pit the zinc or strip the paint faster than you’d think.

Step-by-Step: How I Clean the Blue Spots Off

First, I spray the whole loose tablet area with distilled water to wet it. Then I mix a tiny bit of D/2—about a tablespoon—into a quart of distilled water in my spray bottle. Shake it gently.

Step two: I spray the solution right on the blue spots. Let it sit for a full five minutes. I use that time to pull weeds or just stand there and chat with the dead.

Step three: With the soft brush, I make small circular motions over the blue areas. Not pressing hard. Just enough to lift the stain. The solution does the work. I’ve found that most of the blue comes off in the first pass.

Step four: Rinse thoroughly with more distilled water. I use a second spray bottle for this. Then I pat dry with the microfiber cloth.

Step five: If any blue remains, I repeat the whole thing. Took me three tries on the Henderson monument. Worth it. The inscription is clear as a bell now.

What NOT to Do (Learned the Hard Way)

I once tried a mild vinegar solution on a zinc monument. Bad idea. It dulled the finish. Skip that. Also, steer clear of strong acids or alkaline cleaners—they can eat through the zinc’s patina and leave a blotchy mess. And for heaven’s sake, don’t use a wire brush or steel wool. That scratches the metal and makes future stains worse. Pressure washing is also a no-go—it can blast off loose paint or even dent the thin zinc sheet. I saw a guy do that once. His face when the nameplate fell off was something else.

When to Call a Pro (Or Just Leave It Alone)

Not every blue spot needs scrubbing. If the monument is over a hundred years old and the zinc is very thin, sometimes the blue is part of the natural patina. It’s like a historical fingerprint. I’d say if the spots are powdery or flaking, that’s a sign of active corrosion. Then clean gently. But if they’re just a uniform blue-gray and the inscription is still readable, you might want to leave it. I’ve seen people over-clean and lose the original paint. That’s a shame. Use your judgment. And if you’re unsure, ask a cemetery conservator. Most of us are happy to help.

Frequently Asked Questions

Q: Can I use WD-40 to remove blue spots from a zinc monument?

A: I wouldn’t. WD-40 is a lubricant and solvent, not a cleaner for delicate metal. It can leave a greasy residue that attracts dirt and makes the blue spots worse over time. Stick to a pH-neutral cleaner like D/2.

Q: How often should I clean blue spots off a zinc monument?

A: Once a year is plenty, unless you live in a very wet or polluted area. I do mine every spring. Over-cleaning can wear down the protective coating. Remember, a little blue is natural.

Q: My zinc monument has loose paint around the blue spots. Should I repaint it myself?

A: Not unless you know exactly what type of paint was used historically. Modern paints can react with the zinc and cause more damage. Best to leave painting to a professional or just clean the spots and leave the paint as-is.

Q: Are those blue spots on a zinc monument the same as rust on iron?

A: No, they’re different. Rust is iron oxide, which flakes and eats metal. Blue spots on zinc are zinc carbonate or hydroxide—they can actually form a protective layer if left alone. But if the spots are powdery or lifting the paint, that’s a sign the layer is failing and needs gentle cleaning.

Q: What if the blue spots are on the lettering itself? Will cleaning erase the name?

A: If the lettering is deeply etched into a solid zinc tablet, cleaning with a soft brush and D/2 won’t remove it. But if the lettering is painted or very shallow, be extra careful. I use a cotton swab dipped in the solution for the letters. Go slow.