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Marianna asked: How do I clean concrete decorative blocks? My patio is surrounded by decorative concrete block scenes. They are in good condition, but look dirty and old. I wonder how to clean them. Could I use a power washer or a sandblaster? Would painting work? Thanks
Although the precise method of cleaning dirty concrete decorative blocks will depend on the type of concrete and the exact kind of stain you’re dealing with, this method is highly effective against routine dirt build up. It’s also safe and much less likely to damage the concrete than power washing or using a stronger acid.
You Will Need:
- Soft brush
- Mild soap
- Water
- Bucket
- Rubber gloves
- Eye protection
- Hydrochloric acid
Steps to Remove the Stain:
- Mix a sudsy solution in the bucket with the soap and water.
- Use the soft brush to scrub the soapy water into the decorative concrete. In most cases of dirt build up, this will be all of the cleaning necessary.
- If the concrete is still stained, wear rubber gloves and eye protection while you pour hydrochloric acid on the stain. If you do not have a diluted solution, make sure you dilute it before use, following all label directions.
- Using the same soft brush (rinse it first), scrub the concrete again.
- Repeat as needed.
- Rinse well with clean water.
Additional Tips and Advice
- If needed, you may use a power washer. For best results, add a mild detergent. Be aware, however, that this method can damage ornate concrete. It can also force water into the stone, which can cause more damage over time.
- To maintain the clean, follow up with a concrete sealer or stain. Although you may paint concrete, it should be professionally cleaned and treated before you attempt to do so. Once professionally cleaned and/or treated, use paint labeled for use on concrete and follow all label directions.
I have concrete different style blocks around flower beds and a walkway holding mulch in. Some are tan and white. I want to paint them so how do I clean them first? There are some black spots.
Hi Barbara,
The methods here should work to clean the blocks and that’s good you plan to clean them before painting as it will help the paint to adhere better. The black spots are likely mold, so consider using a mold-prevention treatment like Concrobium on the concrete before painting. There are also mold-resistant paints that you can use to prevent any mold from growing on the surface in the future. Good luck!