Could a laser be used to remove graffiti?

13 June 2010

Question

Hi Chris and team,

Curtains fade because of sunlight. The world has a problem with graffiti. Has anyone tried inventing a laser light that could be used to shine on the graffiti and fade it in a hurry?

Regards
Paul
NZ

Answer

We posed this question to Graeme Hirst from the STFC Central Laser Facility...

Graeme: - Yes it can. They're already used in this application, certainly for cleaning expensive things. The trick is to choose a laser so that the colour of the laser light matches the colour of the graffiti ink. [that can then be used to heat the graffiti ink, and blow it off the wall without heating the wall up.] So, yes, it's a very neat solution for cleaning dirty stuff off expensive things. Unfortunately, it's not always cheap and you do have to make sure there's no one around. Ben: - Is it also true that you can use lasers to have a look through the paint and try, and find fraud in paintings? Graeme: - Yes, you can. Again, you choose the right colour. Now, what you're looking to do is to choose a colour which is not absorbed by the top layer of paint so it goes straight through. It'll be absorbed by something a bit lower down, it'll bounce back off that and whether it's there or not, you will get bounce-back or not and by mapping out the bounce-back, you can look at the layer below the paint layer.

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