Brick walls are very hard to clean off, and hard to paint.
They are hard to clean for one big reason: they have porous surfaces. Think of a dish sponge. If you spray painted it, the paint would go in all of the holes. If you rub a cloth over the surface, you will still have paint in all the holes.
That being said, some brick walls are actually quite smooth, and if they are, you have a much better chance of cleaning them.
How to clean brick
There are two issues. First, you need a strong solvent to loosen the paint up. Second (and people don’t think this) you need to get the paint off the surface. That sounds silly, but when you clean a mailbox, the paint comes off on the cloth. But even if you have a good solvent, how do you get the paint off? (This happened to me - I used a decent solvent and it appeared to be working, but I had no good way to get the solvent and paint off…)
The technique that works best is to soak with a good solvent, then use a strong hose or - far better - a pressure washer to blast off the paint and solvent.
Could you use a lot of solvent and a scrub brush? Yes, but the disposable paper towels I use just get ruined by the surface of the brick. You can use them to get excess liquid off, but you need a real cloth to get off all the paint and solvent.
Warning: Scrub only right over the paint, and not in big circular motions, or you will create a big hazy cloud of paint around the original tag.
You can sand!
If you have time and strength, you can often “sand” off graffiti. I did this once with a long, stiff wire brush. You can also use sandpaper. If you’re persistent, you can sand off a thin layer of brick and get rid of everything.
You will often see people, in desperation, paint brick. It usually does not look good (it’s either the wrong color or they paint over the mortar also) - but I did see a wall near here that was a very nice rusty color! Also, you can buy paints that come out with a texture, and get something for the mortar.
There are only five spray paints that matter in the brick painting world. All are Rustoleum brand:
- Metal Rust Primer (small can, quarts, and gallons)
- Professional Red Rust Primer (tall silver can)
- Textured Old Brick
- Textured Rustic Umber
- Textured Sandstone
The first two are very similar, but the second is a larger can with a gray instead of white label, and a nozzle that sprays paint faster. It is also slightly darker than the first.
The rust primer and old brick are very similar. The Metal Primer is darker, just slightly more orange and covers graffiti better. The Old Brick has slightly more texture and is a little more red. It looks better on many more shades of brick.
Do the differences matter? The Old Brick is nearly impossible to find, you’re better off with the rust-colored primer with a lot of bricks. But, if the bricks are old and have a lot of light red in them, the primer is going to be too dark. If you have dark red, then the primer is going to be great. Here are some examples:
This is one where the rust primer was perfect:
The bunny tag at the top of this is another. What’s an example of the lighter, older bricks that the “Old Brick” is right for? Here are two:
As for the Rustic Umber, it works well for walls, particularly for those with more of an umber shade in them. Its texture is nice. It doesn’t cover graffiti as well as the other two. It also looks different in various light.
The sandstone is one of the things you can use to paint the mortar if your wall has white mortar (many do not). You can spray it on a piece of cardboard and then use a thin brush to paint the mortar.