How to Remove Graffiti from Precast Concrete

Man holding blue spray paint

It’s never a fun moment: you look at your nice precast concrete wall and find ugly graffiti all over it. Even if the sight makes you want to cry, you still need to act fast. The faster you clean it, the easier it is to remove. Here’s the best method for removing graffiti and cleaning your precast concrete walls.

Steps to Remove Graffiti

  • Apply graffiti remover. There are several different brands. Look for something that doesn’t have methanol, methylene chloride, or halogenated solvents.
  • Wait 5-30 minutes. The colder it is outside, the longer you will have to wait. For most products, you should start to see the paint dissolving while you wait. Make sure to touch up areas that you missed or that are too thin while you are waiting. It’s a good idea to reapply even if you don’t think you missed any spots – just to be sure.
  • Use a pressure washer to washer the area – with hot water if you can. Stick to around 1,500-2,000 psi to avoid damaging the concrete. If you have a fan tip nozzle for your pressure washer(ideally a 25-degree tip), use that. This will diffuse the pressure coming out of the nozzle and reduce the risk of damaging the concrete. 
  • If things still don’t look clean enough, repeat the whole process.

Tips for Best Cleaning

Now that you know the steps you need to take to remove the graffiti from your precast concrete wall, here are some additional tips you should consider when cleaning your concrete wall

  • Wait as long as you can. The longer you can allow the cleaner to sit before pressure washing, the better the cleaner will work. You also don’t want to allow the remover to dry out. Find a cleaner that is very low VOC and alcohol-free. Those will evaporate slower and allow more contact time with the paint. You want the cleaner to do most of the heavy lifting. The lower the pressure you need to use to wash everything off, the less damage will be done to the concrete. Also, a lower pressure will allow you to get away with not using an expensive, professional-grade pressure washer.
  • Use heat to your advantage. Graffiti cleaners work better if the air temperature is higher. Do this in the summer if you can. If it’s colder, you will need to allow the cleaner to sit for longer. Using warm water in your pressure washer will help remove more of the graffiti. Professional-grade pressure washers can heat the water. If you don’t have a professional-grade pressure washer, you will need to attach your pressure washer to a faucet or water heater.
  • Avoid acid, soda blasting, and metal bristle brushes. Any of these will etch your concrete – damaging both the look and effectiveness of the concrete. Metal bristle brushes can also potentially leave rust stains on your precast concrete wall. If your concrete is etched, future graffiti will be harder to remove. These methods remove, not just the graffiti, but the outer layer too. This exposes the porous inner part of the concrete, allowing both water and paint to penetrate deeper into the concrete.

If your concrete wall has been cleaned with a harsh method, you should re-seal it or apply an anti-graffiti coating. If you want to remove the weird look left behind by the etching, you can use the process to etch the whole wall to match the etching caused by removing the graffiti. Make sure to use a sealer on the whole wall after.

Ready to have a precast concrete wall or fence? Give American Precast Concrete a call today to get for your free product estimate.