Abstract:
A method for restoring acid etched glass includes grinding the glass and then applying an acid resistant polyester film over the glass. Grinding may be performed in steps going from course to fine grinding pads, and stopping with a 400 grit pad, leaving a somewhat cloudy appearing surface. The polyester film fills in small irregularities in the cloudy glass surface thus eliminating the need to polish the glass.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to restoring glass and in particular to restoring acid etched glass. 
         [0002]    Tagging has long been a problem both due to the damage to property and to the gang related tagging. Glass dipping solution, and glass etching creams, are available at local craft stores. The solutions and creams are made of chemicals, for example, hydrofluoric acid or ammonium biflouride. When the solutions or creams are applied to glass, the glass surface is eaten away leaving a course etched surface. While city ordinances have been proposed to limit the sale of the etching solutions and cremes, such solutions and creams also have legitimate uses, making control difficult. 
         [0003]    In addition to acid etching, taggers and other vandals are known to use sharp objects, for example rocks, scribes, and the like, to etch windows. 
         [0004]    Unfortunately, even mildly etched glass is very expensive to replace or repair using known methods. Large windows are more popular to etch, and also more expensive to replace. Etched glass may be polished to remove etching, but such polishing is expensive, and the etching may be repeated as soon as the glass has been restored. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The present invention addresses the above and other needs by providing a method for restoring acid etched glass which includes grinding the glass and then applying an acid resistant polyester film over the glass. Grinding may be performed in steps going from course to fine grinding pads, and stopping with a 400 grit pad, leaving a somewhat cloudy appearing surface. The polyester film fills in small irregularities in the cloudy glass surface thus eliminating the need to polish the glass. 
         [0006]    In accordance with one aspect of the invention, there is provided a method for restoring etched windows. The method comprises cleaning an etched region of the window, grinding with an electric hand held grinder, set to a low speed, until the etched region is a cloudy region, wetting an area overlapping the cloudy region to be covered with a film with a water solution, laying the film over the wetted area, and smoothing the film against the window using a squeegee. The grinding includes a final step of grinding with an approximately 400 grit pad to create the cloudy region, and may include earlier steps of grinding with more course pads. The film is preferably an acid resistant polymer window film and preferably comprises three approximately two mil thick laminated layers. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0007]    The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
           [0008]      FIG. 1A  is a window with acid etching. 
           [0009]      FIG. 1B  is the window with a cloudy region resulting from grinding. 
           [0010]      FIG. 1C  shows the window with a polymer window film over the ground surface. 
           [0011]      FIG. 2  is a method for restoring an acid etched window according to the present invention. 
       
    
    
       [0012]    Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
         [0014]    A window  10  with acid etching  12  is shown in  FIG. 1 . The acid etching  12  is commonly the result of taggers and is created by applying a solution or cream glass etching chemical, for example, hydrofluoric acid or ammonium biflouride. Although the window  10  may be polished to remove the etching, such polishing is time consuming, expensive, and the acid etching may be repeated. Further, each time a window is polished, material is removed, and therefore, a window may only be polished a limited number of times. Windows with scratches or etching created by rocks, sand paper, scribes, and the like, face the same issues. 
         [0015]    The window  10  is shown in  FIG. 1B  after grinding the region containing the acid etching  12  resulting in a cloudy region  14 . The window  10  may be ground using a 400 grit pad to produce the cloudy region  14 , or may be ground with a series of pads starting with a course pad, and finishing with a 400 grit pad, for example with a 240 grit pad, a 320 grit pad, and finishing with the 400 grit pad. The use of such course pads is advantageous when the acid etching  12  is deep, and use of the 400 grit pad alone would require an unnecessarily long grinding to remove the deep etching. 
         [0016]      FIG. 1C  shows the window  10  with a window film  16  over the cloudy region  14 . The window film  16  has a filling quality which dispels the cloudy appearance of the cloudy region  14  and provides a clear window appearance. Additionally, the window of window film  16  is resistant to the chemicals used for acid etching the window  10 . Although, the window film  16  may be cut or scratched it may be simply replaced without requiring grinding the window again. Further, because the window film is not susceptible to acid etching, taggers are less interested in vandalizing windows covered with the window film  16 . 
         [0017]    An example of a suitable window film  16  is an approximately six mils thick polyester film, for example, three approximately two mils thick laminated layers with a delayed tack adhesive backing. The layered film is preferred because the layers tend to resist cutting better than a single layer film. The Such window film is available from Madico in Woburn, Mass. and sold under the name LCL-600. 
         [0018]      FIG. 2  is a method for restoring an acid etched window according to the present invention. The method includes cleaning the glass surface when necessary, for example, when etching material is present on the glass, at step  20  and grinding the glass surface with an appropriate grit grinding pad at step  22 . Cleaning is generally necessary when residue of the etching solution or creme remains on the window. Grinding is preferably performed using an electric hand held grinder and more preferably a variable speed electric hand held grinder used at low speed, or a low speed electric hand held grinder. The grinding pad is preferably selected from a range of pads including a 240 grit pad, a 320 grit pad, and a 400 grit pad. The grit of the pad is selected based on the depth of the etching, with a courser pad selected for deeper etching. Selecting too fine a pad, will not cause failure, but will require more time and effort to remove the etching. When the etching is deep, and a course pad is used to remove the etching, the course grinding is followed in steps by grinding with finer grit pads. For example, deep etching may be removed with the 240 grit pads, the rough surface created by grinding with the 240 grit pads may be smoothed by grinding with the 320 grit pads, and a somewhat rough surface left by grinding with the 320 grit pads may be ground with the 400 grit pads to create the cloudy surface  14 . 
         [0019]    Following the grinding, the glass may be inspected at step  24  to determine if the etching has been removed. If the cloudy surface  14  has not been created, the grinding is continued at step  26  until the uniform cloudy surface  14  is created. A film layer is applied over the cloudy surface using the following steps: a water and soap solution is prepared at step  28 , the area to be covered with the film is wetted with the water and soap solution at step  30 , the film is placed over the wetted area at step  32 , and the film is smoothed against the window at step  34 . The smoothing is preferably performed using a squeegee. 
         [0020]    While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.