Cleaning a Cast-Concrete Grave Marker From the 1930s (My Backyard-to-Cemetery Story)

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I still remember the day I found that marker, it was buried under a pile of rotting leaves in my grandma’s backyard, near the old chicken coop she never used. I was maybe twelve, digging for worms to go fishing, and my shovel clanked against something hard. I scraped away the dirt and saw the name "Evelyn R. Hargrove — 1934" chiseled into a gray slab. I didn't know who she was. Grandma said Evelyn was a neighbor’s kid who died of scarlet fever, and the family moved away, leaving the marker behind. For years, it just sat there, covered in moss and bird poop. Fast forward thirty years: I’m a cemetary preservation volunteer, and that marker is my project. It’s cast concrete, not marble or granite. And let me tell you—cleaning concrete grave markers is a whole different beast. It’s porous. It’s crumbly. And if you mess up, you ruin history. I learned that the hard way. So here’s what I did, step by step, to bring Evelyn’s marker back from the dead without killing it again.

First, Figure Out What You’re Dealing With

Before you spray anything, you gotta know your stone. Cast concrete from the 1930s is a mix of Portland cement, sand, and aggregate. It looks smooth but feels gritty. It’s way softer than granite. And it soaks up water like a sponge. If you hit it with a pressure washer—big mistake. I’ve seen guys blast the lettering right off. So step one: test a small corner. Wet your finger and rub it. If the surface feels chalky or leaves dust on your hand, it’s fragile. That means no wire brushes. No metal scrapers. No harsh household cleaners. Stick with a pH-neutral, non-ionic cleaner. I use D/2 Biological Solution. It’s what the pros use on old graves. It doesn’t strip the stone. It eats the organic gunk—moss, lichen, bird droppings—without eating the concrete.

Gather Your Tools (Keep It Simple)

You don’t need a fancy kit. Here’s what I used on Evelyn’s marker: a bucket of distilled water (tap water has minerals that leave stains), a soft-bristle nylon brush (the kind you’d use on a car’s paint), plastic scrapers (like the ones for non-stick pans), old towels, and D/2 Biological Solution. I also had a spray bottle and a garden hose with a gentle spray nozzle. That’s it. No pressure washer. No bleach. No acids. I learned that lesson after I ruined a sandstone marker in ’08 by using a wire brush. Never again. For concrete, you want gentle and patient. Took me three tries to get Evelyn’s marker clean. Worth it.

The Cleaning Process: Slow and Steady Wins

First, I soaked the marker with water. Concrete’s porous, so if you spray on cleaner dry, it sucks in the chemicals too deep. I let it sit wet for ten minutes. Then I mixed the D/2 with water according to the bottle—usually a 1:4 ratio. Sprayed it on heavy, like I was painting. Let it sit for 15 minutes. Then I took the nylon brush and scrubbed in circles. Not hard. Just enough to loosen the green stuff. For stubborn lichen, I used the plastic scraper. Gently. Like scraping butter off toast. Then I hosed it off with a gentle spray. Let it dry for an hour. Then I did it again. And again. Three rounds total. Each time, more gunk came off. The last round, the concrete looked almost new—gray, not green. The letters were sharp again. I felt like a kid finding treasure.

Aftercare: Don’t Seal It, Let It Breathe

A lot of people ask me if they should seal concrete markers. My answer: no. Concrete needs to breathe. Sealing traps moisture inside, and when it freezes and thaws, the water expands and cracks the stone. I’ve seen markers split in half because someone put a sealer on. So leave it bare. Just keep it clean. I go back to Evelyn’s marker once a year, spray it with D/2, and rinse. That’s it. Also, make sure the area drains well. If water pools around the base, it’ll wick up and cause spalling. I dug a little trench around Evelyn’s marker to channel water away. Took an hour. Saved her name for another fifty years.

Frequently Asked Questions

Q: Can I use vinegar to clean a concrete grave marker?

A: No. Vinegar is acidic. It will eat away the cement binder in concrete, making it crumbly. Stick with a pH-neutral cleaner like D/2 Biological Solution. It’s made for stone and won’t damage the surface.

Q: How do I remove black lichen spots from a concrete marker?

A: Black lichen is stubborn. You can’t just scrub it off. Use a biological cleaner like D/2. Spray it on, let it sit for 20 minutes, then scrub gently with a nylon brush. It might take two or three treatments. Don’t use bleach—it kills the lichen but leaves stains and weakens the concrete.

Q: What if the concrete marker is crumbling or flaking?

A: If it’s actively falling apart, don’t clean it yourself. Call a profesional conservator. Cleaning can accelerate damage. For minor flaking, you can consolidate the surface with a lime-based consolidant, but that’s advanced work. I’d leave it alone until a pro can look at it.

Q: Is it safe to use a pressure washer on a concrete grave marker?

A: Absolutely not. Pressure washers can blast away the surface, especially on old concrete that’s already weathered. The water pressure forces moisture into the pores, causing freeze-thaw damage later. Use a garden hose with a gentle spray nozzle. Patience is better than power.

Q: How often should I clean a concrete grave marker?

A: Once a year is plenty. More than that and you risk wearing down the surface. I do mine in early spring, before the moss gets a foothold. Just a light spray of D/2 and a rinse. That keeps it looking good without overdoing it.