The day I learned why old slabs have those weird little dots

Was resurfacing a patio in Bakersfield last month, 1970s pour, and I kept noticing these tiny round marks all over the surface. Thought it was some kind of bug or maybe a bad batch of aggregate. Looked it up after work and turns out those are from the old burlap drag method they used to finish back then. The burlap left little fiber marks that look exactly like dots from a distance. Blew my mind. I've been finishing for 12 years and nobody ever told me that. Anyone else run into old finishes that made you double take?

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the_rowan1mo ago

That burlap drag thing, it's actually a little different than the dots you're seeing. The burlap leaves those long, wavy lines, almost like a combed texture, not round dots. Those little circles you're seeing on a 70s slab, I'd bet money that's from a bull float with a honeycomb or dimple pattern, or maybe even old-fashioned hand tamping with a textured pan. I've seen it on a few mid-century pours here in Fresno, and it took me a while too, but once you know what to look for, you can spot the difference pretty fast. Keeping that section visible is a solid move, though, it's a good conversation starter.

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john_fisher1mo ago

Kept a section of that old slab visible when we repoured, just to show the homeowners what burlap drag looked like. Tbh it made me respect the old timers way more, they had tricks we never hear about.

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