How can I remove graffiti from painted walls?

Question

How do I remove graffiti (spray paint and permanent marker) from a wall previously painted with oil-base paint (or perhaps nitro paint - not sure) without damaging the original paint?

I've seen a variety of removal substances on the market, but not sure if they leave the original paint intact. So far I've tried acetone and white spirit - they are more or less effective, but removal process is extremely slow and looks more like an uphill battle than an efficient process.

What ways to remove graffiti from a painted wall are there?

Answer 1

I think your best bet is to just paint over it/re-paint the wall. On exterior concrete/brick walls it is easy to power wash or sandblast it - the goal is to remove everything. However neither of these will work inside - aside from the mess they'd create, they'd probably take more then just the paint off your walls!

You might find some chemicals to help remove it, but because spray paint is paint afterall, you will undoubtedly damage the paint underneeth it. Permanent Markers can often be removed with Isopropyl alcohol if the markings are relatively new - you might have some luck with this on the spray paint too. However, with markers, generally speaking, the longer you leave it, the more difficult it is to remove.

By the time you get this stuff off, fix the wall, re-paint the parts that need it, you'd probably would have spent more time then just repainting.

Answer 2

Steven's answer is pretty much the correct one.

In the past, I've used the 3M magic eraser products. But that, like most chemical/mechanical removal ends up leaving a damaged area that looks just like the original graffiti.

Your best bet is to repaint.

When you do repaint, you can consider looking at anti graffiti coatings:

http://www.sherwin-williams.com/pro/products/pro_industrial_antigraffiti_coating/

Or...consider landscaping...rose bushes or some other similar shrubbery that make the wall less appealing to paint.

Answer 3

I'm rather disappointed to find almost no useful information on how to remove a specific painting substance from a specific type of painted wall. That's surprising since graffiti is a widespread problem and I guess millions of people face it every year. The typical answer indeed seems to be "repaint and get over it" yet repainting would be a lot of hassle in my scenario - even sub-optimally removed graffiti would be beneficial.

So I'll describe my findings here. Fact is one has to find an appropriate chemical which is usually some organic solvent like acetone. Each solvent will have two key parameters. Parameter one is whether it dissolves the painting. Parameter two is whether it dissolves the original paint. Obviously you're only interested in solvents that do dissolve the painting and don't dissolve the original paint too much and the don't dissolve the original paint more that they dissolve the painting.

So I was combatting spray paint and permanent marker used over some kind of oil-based or maybe nitro original paint.

The "white spirit" solvent would dissolve the spray paint very well and wouldn't dissolve the original paint at all. So I wasted something like a half roll of paper towels to have about one square meter of surface cleaned and the spray paint was removed. However this solvent would have no effect on permanent marker.

Acetone would dissolve the permanent marker and also it would mildly dissolve the original paint. I wouldn't mind having a thin layer of the original paint removed, but the problem was that dissolved marker would mix with dissolved paint and that would leave ugly stains in the upper layer of the paint.

Also I tried windscreen washer concentrate which is water plus isopropyl alcohol plus some unrelated chemistry. It would dissolve the marker and have no effect on the paint but the dissolved marker would burr and immediately adhere to the surrounding paint so I had to wipe the burrs immediately and still would have minor low-contrast stains.

Then I figured out how to combine acetone and isopropil alcohol. The deal is that the marker trace is rather thick - the lower layer is in direct contact with the base and the upper layer is not in contact with the base, it is separated with the lower layer. The alcohol wouldn't remove the lower layer because of it good adhesion to the base, but it would dissolve the upper layer. The acetone would dissolve everything and mix it int ugly mess, most of which was the marker ink upper layer. So I used alcohol to remove the upper layer, and then acetone to remove the lower layer together with some original paint. That did some damage to the original paint, but it looks minor especially compared to the high-contrast graffiti drawing removed. In my opinion that was a win, but not an epic one.

Answer 4

Chemicals are an effective way to remove it. However, damage to the original paint will happen. Power washing is also a very effective way to remove it but damage to the original paint will also occur. Unless you can find a remover that will only remove the type of paint the graffiti is done in you will end up having to repaint the wall.

Answer 5

I had graffiti on my painted fence, and acetone worked like a charm to remove it, very easy! I still painted a very light coat of paint over once I had removed most of the spray paint, it took me 15 minutes and the acetone didn't wreck the paint on the fence. In my case, the spray paint was only about 12 hours old.

Answer 6

You won't be able to remove graffiti and leave your background paint intact. The only way is to strip it all down, paint the wall again and lay an anti-graffiti coating on the newly painted wall that will allow you to wash off any graffiti in future, should it appear again.