Ghost image after graffiti removal

[the_GUNN_man]

I have had quite a few call recently about removing graffiti. It has mostly all been from vinyl which I have been able to remove. I came across a school that had been spray painted on a concrete wall. It is a very porus(rough) wall and when I washed it most everything came off except the oil from the paint. You can see where it darkened the concrete. I used everything I had and you can still see the ghost image. All the paint has been removed. Any suggestions on what to do?

[Craig]

Give up.

Some are oil based, acid based (which can etch glass and leave a "ghost") etc. If it is colored brick you are even more up a creek. It is near impossible as far as I know to remove the contaminant any further without causing damage.

[the_GUNN_man]

What if the image that you can still see is pretty vulgar? I was wondering if you could then use some kind of oil to spray on the wall so that you can no longer see what it said. It would be better to have a big dark spot then to still be able to read obscenities.

[RyanH]

Test dap some Goof-Off around it and see if that blends it in.

[newlook]

and you can pick up some Goof Off from any hardware or HD store

[dave]

I have had quite a few call recently about removing graffiti. It has mostly all been from vinyl which I have been able to remove. I came across a school that had been spray painted on a concrete wall. It is a very porus(rough) wall and when I washed it most everything came off except the oil from the paint. You can see where it darkened the concrete. I used everything I had and you can still see the ghost image. All the paint has been removed. Any suggestions on what to do?

try a very caustic degreaser the one i use has 25% sodium hydroxide give it some dwell time and a brush it worked well for a brick wall and some roller doors that i used it on recently not for painted surfaces lol.