If you are an artist who has created a public mural, or if you know and love a public mural that needs protection, the Mural Rescue Program provides important services for a select group of murals based on the following criteria:
· Aesthetic merit
· Geographic and cultural diversity
· Feasibility
· Public Access
Until now MCLA conducted an annual application process. At it May Board meeting, it was decided that submissions may be made on behalf of a particular mural irregardless of any deadline consideration.
To order an application call or write the Mural Conservancy:
(213) 481-1186, PO Box 86244, Los Angeles, CA 90086.
Or, print out a form directly from the Web site:
http://artscenecal.com/MCLA.html
By Nathan Zakheim
THE FOLLOWING IS A TRUE ACCOUNT AND IS MEANT AS A GUIDE FOR THOSE VICTIMIZED BY THE DECEPTIVE PROMISES OF URETHANE:
We were brought to inspect reports of deterioration of a coating on a public mural that shall remain unnamed.
1. The report of unpeeling paint led us to discover that the urethane coating had finally begun to detach itself from the painted mural surface in larger and larger areas. As our previous inspection report indicated, the de-lamination began as sporadic, and having severely oxidized (which included yellowing as well as a tendency toward opacity) obscured the vivid colors beneath the areas where the yellowed urethane coating was lifted from the painted surface, but not yet flaked away from the surface. The underlying brilliant colors would then appear as pastel due to the semi-opacity of the urethane coating.
2. Now that larger areas have delaminated, we can see that there is a largely intact field of color under the exfoliated urethane sheets, but that the pigment is now covered with very severe discoloring and thick layers of road grime that has sifted into the "pockets" formed by the somewhat loosened coating.
3. "Road grime" consists of the following:
Smog and auto emission residue. Airborne dust particles. Powder from brake lining wear as well as powdered tire rubber. Organic matter from de-composing tree leaves, grass, paper etc. Spores and molds that begin to take root in the organic matter.
4. The road grime has built up a film over the exposed paint layer and in some cases has caked into a highly pigmented crust of pollutants.
5. As the urethane began to split from the wall, the surface of the mural paint has tended to adhere to it, and thus the paint layer has been split to some degree or another. No doubt the tight covering of urethane has also created some sort of micro-environment that has promoted the break-down of the mural paint by facilitating water vapor to form from moisture that has leeched in from the reverse side of the concrete wall that supports the mural (The sun heating the front of the mural both draws the moisture to the urethane covered surface, but also causes it to become vapor that can then attack the water soluble elements in the mural paint itself). If the urethane coating were not there, the vapor would pass through the mural paint and be evaporated into the atmosphere causing little or no damage to the paint film.
6. It is also likely that the paint layer did not have enough binder at the outset. We draw this conclusion due to the fact that the "skin" (surface layer) of the mural paint became fused to the urethane coating, and when the coating began to peel away, it took a very thin layer of the mural paint surface with it leaving a layer of underbound pigment that tends to be friable and powder. This would indicate that the paint used did not contain a sufficient amount of binder to fully saturate the pigment of the paint. Another explanation would be that the microenvironment created under the urethane coating caused the binder to crystalize and for the water soluble elements to break down, causing the paint to appear friable.
NOTE: If good quality paints are used, with acrylic gel or medium added to the tube or jar paints, the mural paint film thus formed becomes very "plastic" or "rubbery" and resists the tendency to powder. Of course, the acrylic medium can itself crystalize, and begin to form microscopic "crumbs" that give the impression of underbound pigments.
Such crumbling of the acrylic layer can be immediately corrected by spraying the affected area with mist coats of xylene. For even better results, a 10% solution of Acryloid B-66 or B-72 diluted in xylene can be applied via spray to the surface of the crumbling mural surface in gradual layers until full saturation is achieved. This not only consolidates the crystallized crumbs of acrylic into a flexible plastic film once again, but fully restores the original depth of color that invariably takes on a pastel aspect during the crumbling process. Refraction of light makes the broken surface of the pigment layer appear pastel, just as ceramic glazes tend to appear "white" until fired.
PROPOSED TREATMENTS
1. Obtain a source of hot water (Buckets, drums, water-blasting unit with heater, gas fired burner on which pots of water can be heated, "igloo coolers" filled with boiling water etc.)
2. Mix the water to be applied with Shaklee Basic-H. (1/16 tsp per gallon of water)
3. Spray a generous application of this solution onto the entire mural being careful not to brush or scrub any area at first.
4. Use small "pattern wheels" (rowers) to perforate the blistering areas of urethane.
5. Use small hand held sprayers and a sponge to thoroughly wet areas that are covered with caked on black road grime.
6. Carefully wipe the areas of grime away with the sponge. Stop immediately if there is excessive pigment loss.
7. Go to the areas that are fully blistered and carefully scrub them with a bristle scrub brush (a vegetable scrub brush works well) while continually spraying the water mixture onto the surface.
8. You will find that some areas will clean easily, while others stubbornly resist. Once the easy areas are clean, spray more solution at an angle to the resistant edges and wait for a while. (if they begin to loosen or curl back, then scrub the new areas carefully with the brush. If they do not loosen, add more pinholes with the wheel and repeat the process. If they cannot be loosened, then leave them alone.
9. Rinse the wall with flowing, clear water. (A pressure system with a reservoir would be useful. The pressure should be set at no more than 75 psi.)
NOTE: The end result, if the coating removal is incomplete, will have a unsightly blotchy appearance almost identical to a badly peeling sunburn. The newly revealed mural surface will be bright and colorful, and the areas still covered by a stubborn layer of urethane, will be several shades darker. This contrast may not be so very noticeable to the traffic driving by.
FINAL PROCEDURES FOR CONSOLIDATION AND PROTECTIVE COATINGS
1. Allow the surface to dry for at least one day. This means a HOT day. With temperatures below 60 degrees F. several drying days should be allowed
2. Spray Acryloid B-72 dissolved in xylene onto the newly cleaned areas. Overspray onto the urethane is O.K. if not excessive.
3. When the Acryloid B-72 is set (2-4 hours), spray a coating of Soluvar onto the surface as an intermediate protective reversible varnish. Soluvar, which dissolves in petroleum naphtha, can act as a graffiti barrier, since it can be removed from under the spray-can graffiti. It is not a good substitute for sacrificial wax, however, as the spray graffiti sometimes penetrates the Soluvar layer and attacks the mural surface.
4. Wait for six months or a year to repeat the above process on any areas of urethane coating that may remain. A third treatment should not be required as the accelerated disintegration of the urethane will probably be complete by that time.
5. Apply the sacrificial spray wax to the areas that are clear of the urethane. It is not desirable for the remaining urethane coated areas to be treated with sacrificial wax. It is advisable to mask such areas with visqueen when the wax is being applied.