VIOLiN
Harmless
Posts: 7
Registered: 13-2-2017
Member Is Offline
Mood: No Mood
|
|
Graffiti Removal
Hello everyone. Unfortunately, one of our walls was graffitied. It is on a concrete block wall. I have tried many things. I've given 2 different types
of graffiti removers a go. (Usually phosphoric acid, right?). I have also tried using some of my dichloromethane. Nothing seems to be working! I have
even used a wire brush and have pressure washed! So frustrating. Do any of you have any ideas to remove it? Keep in mind strong acids like
H2SO4 wouldn't work because it would etch/react with the concrete.
Thank you!
|
|
|
argyrium
Hazard to Others
Posts: 123
Registered: 3-2-2008
Location: Pacific
Member Is Offline
Mood: No Mood
|
|
You have not given many details that might help with the type of offense.
Is the concrete surface "raw" or painted? If raw, this may be complicated. Is the graffiti spray paint or a marker? What colour(s)?
Often modern spray paints can be dealt with using MS/DCM or other with surfactants and water (+ elbow grease).
I despise "taggers"..
|
|
|
VIOLiN
Harmless
Posts: 7
Registered: 13-2-2017
Member Is Offline
Mood: No Mood
|
|
The concrete is raw, unfortunately... In addition to this, we cannot paint over it. The graffiti is black spray paint. I'll give the DCM and
surfactant mix a go. Thank you so much for your help.
|
|
|
Sulaiman
International Hazard
Posts: 3558
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
HCl / muriatic acid together with abrasion will remove the top layer of concrete, taking the paint with it.
as always, first test on an area not normally visible.
CAUTION : Hobby Chemist, not Professional or even Amateur
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
Three replies and no mention of toluene or xylene? Considering that's the solvent used in spray paint, if the paint is a cheap brand (which it
usually is; graphitti kids aren't generally a wealthy bunch) then those solvents will dissolve it.
[Edited on 4/17/17 by Melgar]
|
|
|
argyrium
Hazard to Others
Posts: 123
Registered: 3-2-2008
Location: Pacific
Member Is Offline
Mood: No Mood
|
|
Actually, one generally does not want to "dissolve" the paint, as this often will cause the pigments to migrate further into other areas before being
removed. One wants to cause the paint film to swell and become dispersed into a soap/detergent mixture and then removed w/ water. The use of
aromatics, esters, and alcohols may aid in the break-up of the films but best kept at lower levels in a mix to prevent the redistribution of the
paint. Addition of a thickener (Klucel, Pemulen, Carpool, xanthin gum, or similar) will help hold the solvents in place and increase contact time.
If thickeners are unavailable, you might try making a poultice from fumed silica of similar.
I'd stay away from acids for the reason alluded to above, but the inclusion of an ionic base would probably be OK or advantageous.
Raw stone/concrete can be difficult to treat.
Please, let us know what happens.
[Edited on 18-4-2017 by argyrium]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
