Let’s talk about acid-washed concrete—the misunderstood rebel of the concrete finishing world. It’s gritty. It’s honest. It doesn’t wear a tie. But when it’s done right? It delivers a bold, natural finish that screams architectural attitude.
At NZ Grinders, we get a fair few questions about acid washing. Mostly from people wondering, “Is this the same as polished concrete?” (Short answer: not even close.) And occasionally from someone who’s heard a horror story about it going wrong.
So, let’s break it down: what acid-washed concrete really is, where it works beautifully, and how we do it properly without ending up with a blotchy backyard nightmare.
What Is Acid-Washed Concrete, Really?
Acid washing, sometimes called acid etching, is a surface treatment that reacts with the top layer of your concrete to expose the fine sand or aggregate just beneath the surface.
It’s a chemical process—not mechanical like grinding or polishing. We apply a mild acid (often hydrochloric or phosphoric), which eats away the laitance (that chalky top layer) and reveals a textured, natural finish with more grip and variation.
It doesn’t shine like polished concrete. It doesn’t get sealed up in resin like an epoxy floor. It’s raw, matte, and tactile—like stone that’s been worn by time and tide.
Why People Choose Acid Washing
It’s Got Natural Texture and Grit (In a Good Way)
If you’re not into the super-sleek, high-gloss look of polished concrete, acid washing offers something more organic. The finish is slightly rough underfoot—think sandy limestone or weathered sandstone.
That means better grip, which is why it’s a great choice for:
- Pool surrounds
- Patios and courtyards
- Outdoor walkways
- Driveways
- Breezeways and alfresco areas
Anywhere that gets wet, dirty, or needs some traction—but still needs to look stylish.
It’s Budget-Friendly
Because acid washing is a chemical treatment, not a mechanical grind or polish, it’s generally quicker to complete. That can mean lower labour and equipment costs—perfect for larger areas like driveways or external hardscapes.
Builders love it because it’s fast. Clients love it because it looks architectural without blowing the budget. We love it because we’re good at it.
It Pairs Beautifully with Honed Concrete or Polished Interiors
We often use acid-washed concrete as the outdoor counterpart to polished interior floors. It’s a great way to keep the same concrete slab running throughout the home while still adapting to the different needs of indoor and outdoor zones.
The transition looks seamless. The surface performance matches the environment. And your guests won’t even realise how cleverly designed it is until you smugly point it out.
Where Acid Washing Really Shines
We’ve acid washed:
- Modern coastal homes with exposed concrete patios
- Pool surrounds needing non-slip, barefoot-friendly surfaces
- Commercial entryways that wanted grip without boring broom-finished concrete
- Driveways for high-end homes that wanted more visual interest
And here’s a fun fact: acid-washed concrete develops a patina over time that gets better with age. It doesn’t fade or peel. It just weathers, gracefully—like your favourite leather jacket.
What to Know Before You Go Full Acid Mode
Now, a warning: acid washing is unforgiving if the slab isn’t poured correctly. Poor finishing, inconsistent curing, or contaminants in the surface can lead to uneven colour and texture.
That’s why at NZ Grinders, we’re picky. We assess the slab before we start. We’ll tell you if the surface is going to work or if another treatment might be a better option. We’d rather lose a job than botch a result.
And yes—we always neutralise and pressure wash the slab properly afterward. We’ve seen what happens when cowboys skip that step. (Hint: the floor doesn’t stay acid-washed—it turns acid-ruined.)
Can You Seal Acid-Washed Concrete?
Yes! In fact, we recommend it.
We typically finish acid-washed concrete with a penetrating sealer to lock in the finish and protect the surface from staining or moisture. It won’t gloss the concrete up like a grind-and-seal—it keeps the matte look but makes cleaning much easier.
We’ve also got slip-resistant options that are great for commercial and hospitality applications. Ask us, and we’ll sort the best combo for your space.
Final Word: Acid Wash Has Edge, If You Do It Right
If you want your concrete to look tough but elegant, raw but refined, and durable without trying too hard—acid washing might be the answer. It’s not for every space. But when it suits? It really suits.
At NZ Grinders, we’ve done everything from understated courtyards to full-on, showstopper driveways. And we’ll be honest with you from the start. If your slab isn’t right for acid washing, we’ll help you find a better finish.
But if it is? We’ll bring it to life in a way that makes your neighbours jealous.
For project-specific advice or information, give us a call:
📍 North Island – Glen: 021-434-199
📍 South Island – Mike: 027-281-8815
📧 Or email Ian, our sales manager, through our Contact Page.
Let’s get your concrete looking sharp, strong, and perfectly weathered.