Color  Filling
©1998-2004 Antares,  Inc.

Description
Color filling is a term used within  the awards and engraving industry to describe a variety of techniques used  to add color or contrast to engraving. Even though there are a wide  variety of engraving materials available in a multitude of colors,  thicknesses, and finishes, there are often times when it is desirable to  color the engraving to make it stand out or enhance the overall appearance  of the product.


Oxidizing
There are three basic  processes or applications that fall under the category of color filling.  The most common, which is used to blacken engraving on brass and aluminum  is actually an oxidation process done with a mild acid that blackens the  exposed metal upon contact. Since this oxidizing process isn't selective  as to where it works, it can only be used on metals that have some kind of  coating that is removed in the engraving process.

For example, the  commercially prepared brass common to the industry is coated with lacquer  or some other durable finish. Aluminum can be coated in a similar manner,  or it can be anodized. Anodizing is an electro-chemical process that seals  the surface of the metal and prevents natural oxidation. When we remove  any of these finishes with a diamond graver, burnisher, or a rotary  cutter, the exposed areas can be blackened with the oxidation solution  without having it affect the rest of the plate.

Oxidizers are  available for both brass and aluminum. They are reasonably effective and  the only consideration is that it is fresh and free of contaminants. While  most oxidizers are supplied with a dauber, this may not be the best way to  apply it since you would be continuously putting the dirty applicator back  in the solution. A better method is to use cotton swabs and discard them  after each use. It is equally important that the engraving be clean and  free of any oil or even fingerprints. Since the bare metal goes through a  natural oxidation when it is exposed to the air, it is a good idea to  oxidize it soon after it is engraved so the full effect of the oxidizer is  achieved.

Apply the oxidizer liberally to all of the engraving. It  sometimes helps to actually "scrub" it into the letters with the swab.  Allow the engraving to darken and when the desired effect is achieved,  rinse the plate with water. Rinsing will dilute the acid and stop the  oxidation process. If the oxidizer is left on too long, the process will  continue and the blackened areas may turn gray and chalky and even flake  out of the engraving.

After rinsing, blot the plate softly with a  cloth or paper towel - don't wipe it because it is possible to rub the  black out of the letters. You can make a final clean-up after the plate  has dried. If there are any areas that didn't take, you can go back and  repeat the process. Oxidized engraving tends to have a dull, lusterless  appearance. It is possible to enhance the appearance by applying  silicones, spray lubricants, or even furniture polish to the plate but  while these methods tend to darken and add gloss to the lettering, their  effects usually diminish in a relatively short time.


Paint  Stick
Actual color filling where a fill material is applied into  the engraving can only be done on rotary engraved plates with sufficient  depth and is usually done with paint or a paint stick. A paint stick looks  like a large crayon, is available in a variety of colors, and is simple to  use.

First, shave the end of the stick with a knife or razor blade  to remove any skin that has formed. Next, rub the stick back and forth  across the engraving until the letters are filled, and then wipe off the  excess with a cloth or paper towel. On some surfaces, the paint stick will  leave an oily residue that can stain the surface of the plate. Sometimes  alcohol or paint thinner is effective in removing this film, but the  easiest way to completely clean the template is to allow it to dry  overnight and then wash it using warm water and a non-abrasive cleaner.  While this method of filling is easy and reasonably durable, it never gets  completely hard and doesn't offer the smooth, glossy appearance that paint  does.


Paint Filling
Paint filling, while a little  more difficult than other methods, offers the broadest number of options  in terms of materials, colors, and applications. For metals and rigid  plastics (phenolics and acrylics), it is best to use a fast-drying, oil  based enamel to fill and mineral spirits for the cleaning operation. On  soft plastics such as flexible engraving stock and other materials that  may be affected by caustic solvents, use latex or acrylic paints and water  or alcohol for clean-up. Other than this, the procedure essentially the  same for both. In addition to the paint, all that's required is an  inexpensive brush, an old phone book, and some pieces of stiff paper or  cardboard (about the size and weight of a business card).

The  engraving should be smooth, free of burrs, and have sufficient depth to  hold the paint. As a rule of thumb, with characters up to 1/4" high,  engrave to a depth of .010" - .012". On larger characters, it is advisable  to go .015" - .020" deep depending on the line width and filling technique  used.

The paint should be thick enough so that it does not allow  the cutter marks to show through after it has dried. Using the brush,  apply the paint liberally so that the engraving is completely filled.  Immediately after filling, hold one edge of the cardboard so that its  straight edge rests against the plate and scrape off the excess paint  leaving just a thin film. Allow the plate to dry for several minutes until  the paint has started to set-up and the surface can be wiped without  disturbing the paint in the engraving. The time varies depending on the  paint being used, but 5-10 minutes would be a good starting  point.

The next step is the initial clean up of the surface of the  plate. Wrap two or three thicknesses of a lint-free cloth tightly around a  wood or plastic block and dampen it with thinner. Wipe the surface of the  plate lightly, in one direction, until the paint residue is removed. On  small plates, an easier method of cleaning is to wipe the plate across the  cloth. A widely used and effective alternative to the cloth method is to  use pages from a telephone book. Their texture allows them to absorb the  thinner, and any problem with lint is virtually eliminated.

There  are two key things to remember that can mean the difference between  success and failure. One is not to use too much thinner. If the cloth or  paper is too wet, thinner will seep into the engraving and attack the  paint, ruining the appearance. Secondly, when wiping, do it lightly to  prevent the cloth from coming in contact with the paint in the  characters.

After the plate has been wiped clean, there may still  be haze that requires some additional cleaning. It is best to allow the  plate to dry, preferably overnight, and then to do the final clean-up when  the paint in the characters has completely set. You may want to use soap  and water or a cleaner that will remove any oily residue left by the paint  and thinner.

When filling larger letters, it is possible to  eliminate most, if not all, of the cleaning and wiping by using an  applicator that allows you to apply the paint directly into the engraving.  Some systems utilize small plastic squeeze bottles with needle-like  nozzles while others are more elaborate mechanical dispensing systems.  With either method, paint is squeezed through the fine nozzle directly  into the engraved character. With a little practice, it's easy to become  adept enough to eliminate the need for major clean-up.

Some of the  best sources for small amounts of paint in a rainbow of colors are  touch-up paint from the automotive store, and paint sold at hobby and art  supply stores. Always test the paint before applying it to your finished  engraving to make sure it will not effect the plastic.

Step 1:
Fill engraved letters with paint.

Step 2:
Scrape off excess paint
with card  stock.

Step 3:
Wipe clean with block wrapped
with  cloth dampened with thinner.

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