Removing Graffiti from Historic Masonry

Removing Graffiti from Historic Masonry

World’s Best Graffiti Removal products have been depended on for decades for the removal and protection of historic buildings and monuments. The following notes will address the most common products and techniques used in the removal of graffiti from historic masonry surfaces.

Museum of Fine Arts in Santiago, Chile was expertly cleaned & restored by Alerta Graffiti using Vanish Paint & Graffiti Remover.

Firstly, it is worth noting that all graffiti eventually fades. Some ink and felt pen markers can be gone in days and some spray paints can fade significantly in a year. Household paints may fade within 10 years. Consequently,  It’s much better to take your time and test first rather than attempt removal techniques that will cause permanent damage. As a rule soda or sandblasting and other abrasive cleaning techniques are not an option for cleaning historic buildings. Any pitted, sanded or  damaged surfaces can be TEN times harder to remove graffiti from than undamaged surfaces.

The main product used in removing graffiti from historic masonry, brick, stone, granite, marble, and limestone, and other natural building surfaces is  Bare Brick Stone & Masonry Graffiti Remover (BBSM). It is highly effective and designed to rinse at lower pressure to avoid the presence of insoluble salts being left in the masonry. The advantage of this unique product is that it penetrates and encapsulates the graffiti all around turning it into an emulsifiable soap that is easily rinsed away.

Steaming hot water is almost always preferable when rinsing already dissolved graffiti from historic masonry and can be extremely important on marble and limestone or when lower pressure is desired on masonry and mortar joints.

Any building which has suddenly been washed (even with clean water) after being dry for many years can give rise to what we call ‘secondary efflorescence’ which appears as soft fluffy ‘salts’. This  in itself is not harmful and will disappear quickly, never to return. This is not to be confused with the production and consequential rise of harmful salts which cause the spalling of masonry surfaces.

In our experience, we have never witnessed such a resulting outcome unless the building has  not been rinsed properly, or is situated in a repetitive wetting and drying situation.

Generally, graffiti shadows can be avoided by flood coating with Bare Brick Stone & Masonry Graffiti Remover several times and leaving it on for extended dwell times. 

Still, if a threatened shadow persists follow the notes below.

If the graffiti was from inks, dyes, boot polish or ANY color spray paint with RED pigments in it (for example reds, browns, oranges, pinks, purples, etc.) apply Feltpen Fadeout thickly and reapply if needed. You can also cover it with black plastic so it stays wetter longer. Once you see the stain begin to fade it will disappear completely. Reapply until it appears that no more fading will occur. See “Working with Feltpen Fadeout” and Feltpen Fadeout TDS sheet for further instructions and illustrated examples.

Use Feltpen Fadeout for the complete removal of red spray paints. Use it before or after rinsing BBSM.

For black and blue spray can paints that are threatening a shadow you should first apply several flood coats of BBSM, and consider a coat of Transgel on top, overnight. This will help keep it all wetter longer and dissolve graffiti more thoroughly. Only do this if it is safe from the general public. Consider wrapping a plastic sheeting and employ a guard if you have to.

In the morning, use very hot water with a pressure washer. You may have to use the gun quite close to the surface so as to avoid prolonged time in gunning in one spot only. Keep the tip moving very fast around, over, below and above the graffiti shadow.

On limestone it is not uncommon to see a residual shadow, even after extended dwell times with BBSMThis type of stain can be easily removed using a diluted muriatic solution. Use 4 parts water; 1 part Muriatic (stronger dilutions can be utilized.

a. Wet surface down thoroughly before applying).

b. Brush on the acidic solution, agitate with a brush, and rinse off with a pressure washer.

c. Repeat as needed.

Courtesy of NYC Power Wash

This technique will ultimately fix the problem and you should be left with a perfect-looking wall like this example above.

Protecting Historic Buildings and Monuments from Graffiti

Please Note: Limestone, granite and marble are valuable substrates and ideally need to be protected when used in areas susceptible to graffiti. 

4G Surface Guard and World's Best Graffiti Coating are ideally suited for the protection of natural stone buildings from graffiti, grease, grime and pollution. These products are designed to be virtually invisible on natural building surfaces. Please see several prominent case studies here.

Hot Tip! For contractors offering World's Best Graffiti Coating a rate of approx. $1 per square ft. (supplied and applied) for World's Best Graffiti Coating can add great value to a job and will prevent any staining issues from occurring in the future. You may even consider guaranteeing a graffiti free building by including free removals for a period of time after.

Products Mentioned

3 Golden Rules

1) If graffiti is not coming off easily, you're doing it wrong! You may require a change of tact or use of another product.

2) If you can't remove a little bit of graffiti, then you're not going to remove a lot. TEST FIRST before applying product to an entire job. This way you can determine if you’re on the right track before embarking on full scale removals.

3) If you're working hard, you're doing it wrong. Forget the scrubbing, blasting and any other abrasive measures. Put simply, either your products are working or they’re not. Any problems can be taken care of with the right technique.

Expert advice

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Removing Graffiti from Historic Masonry