Painting on Metal Panels

In this article I will share with you what I learned from master painters, Sal Cabrera and Bill Riedel, as well as explain the step-by-step process that I used in painting on a metal panel. For this story, I will be painting a cow skull, which is a popular artistic motif in the world of automotive artists and pinstripers.   

Proper Prior Preparation. Before you paint anything, make sure you thoroughly clean the substrate. Proper prior preparation prevents painting problems.

If you are painting on a painted metal panel, such as Dibond, proper surface preparation includes the following steps:

Wash the panel with warm water and detergent.  Rinse after washing with clean water and dry.  (If you are a cleaning fanatic, additional cleaning with precleaner (wax and grease remover) and a final wipe with isopropyl alcohol never hurts.) If you don’t clean contaminants off of the surface before scuffing it, you can drive the contaminants into the paint job.
  • Scuff the panel with a red or grey Scotchbrite® pad.  Make sure that the panel is completely scuffed so that the entire surface is dull, with no shiny areas.
  • After scuffing the panel, wipe it down again with precleaner. The proper way to use this or any other solvent cleaner is to wet the surface with the cleaner. Before it evaporates, wipe it off of the panel with a clean rag. 
  •  A final wipe with isopropyl alcohol, will remove any oily residue left by the precleaner.

Backgrounds. The panel that I used for my background, was gilded with copper leaf. The panel was then glazed with mixtures of 1 Shot Tinting Clear and bronzing powders, to give an antique look.  Stippling on the paint also gave the panel a corroded and aged texture. Afterwards, I painted a faux patina using tinted 1 Shot Aqua lettering enamel.

Keep you backgrounds simple and uncluttered.  That doesn’t mean that your background should be one color solid color.  That would be uninteresting. Backgrounds should contrast in value and hue with the primary subject matter, but should not distract from the primary focus of the painting.

Point of Reference.  After studying numerous photographs of cow skull photographs and paintings, I didn’t find anything that I was totally satisfied with, so I sketched a composite drawing shown in photo #1.  For me, sketching a design helps me understand the values in a picture, identifying the highlights, midtones and shadows.  It also helps me focus on a very important aspect of any illustration or graphic composition: “where is the light source?” When you are painting, it always helps to have you sketch or photograph close by to refer to as you are working.

Photo #1

Using white Saral transfer paper, I copied the outline onto the panel. (See photo #2.)  Saral paper is similar to carbon paper.  Available in a variety of colors, you can buy it on-line from Dick Blick at  “There’s nothing wrong in starting your painting with a tracing,” says Bill Riedel.  “Even the masters from centuries past used this technique.  Usually when I begin a portrait painting, I will trace an outline of the most important features, such as the eyes, nose, mouth and an outline of the face.”

Photo #2

Using RTape AT60 application film as a frisket, I cut a stencil for the base coating of white. (See photo #3.) Many sign people, such as Sal Cabrera, use AT60 as a frisket, when doing illustrations or portraits.  It works great whether you are using a sign enamel such as 1 Shot or Ronan paints or an automotive acrylic urethane, such as House of Kolor (HOK) paints. 

Photo #3

Test, Don’t Guess. Whatever film you use for masking, you should test it with the paint that you will use.  Heavy concentrations of solvents in the paint can wrinkle some masking films, causing them to edge lift, resulting in the paint bleeding under the film.

On the white base coat, I freehand sketched the cow skull.  This drawing will serve as a guide for my painting.  To prevent my sketch from smearing, I sprayed it with Butch Anton’s Frog Juice (See photo #4.)

Photo #4

Many artists begin their composition with either a sketch or underpainting.  “Before I start painting, I usually do a quick sketch,”  says Bill Riedel.  “I don’t spend a lot of time doing an elaborate drawing.  That would just slow me down.  Instead, I keep the sketch simple and only outline the person’s basic features. Then I start to paint the hair and eyebrows.  After that I work the more prominent features: the eyes, nose and mouth. Nothing is more important than the eyes. As they say, they are the windows to the soul.”

You might think that sketching the composition first is a bit of a  cheat.  Maybe it is.  Nevertheless, it is a method that has worked for painters for hundreds of years.  The real old time painters, such as Rembrandt, Michelangelo and Titian, all began their paintings with an initial layer, called an “underpainting”,  that served as their layouts for their compositions.

The traditional underpainting is, of course, painted, not drawn with pencils. Many of the masters used warm earth tones to map out the basic shapes and highlights and shadows in their composition.  As well as helping the painter organize his painting, the colors used in the underpainting can also imbue the painting with a mood.  Earth tones can create a sense of warmth, while neutral colors can impart a cooler feeling.  

In developing the underpainting, many painters will thin the paint.  1 Shot paint can be thinned with either one of the company’s reducers or with turpentine.  To keep any runny paint from running down and ruining your painting, you may want to lay your panel or canvas on a horizontal surface.

Developing Your Composition. Whether you are a beginner or experienced professional, first
developing the basic highlights, shadows and midtones, with layers of glaze can help you get the values of your composition correct. After these tonal values have been established, you can then add the colored glazes.

In painting the cow skull I used a number of glazes to create the colors that I wanted. While the terms “glaze” and “wash” are frequently used interchangeably, they are not synonymous. A glaze is a transparent paint.

My friend, Sal Cabrera, frequently creates his glazes, beginning with a base of tinting clear and then adding a little paint. How little is a little? Sal measures his formulations in drops. One glaze that I used for my cow skull painting consisted of ½ oz. of 1 Shot Tinting Clear, 2 drops of Polar White, 1 drop of Primrose Yellow and 1 drop of Emerald Green.

Whereas a glaze begins with a medium such as Tinting Clear, a wash is a diluted paint. When using an enamel, such as 1 Shot you can use either the company’s reducer or turpentine. By diluting the paint, you make it semi-opaque.

Whereas indirect painting uses transparent glazes and washes to achieve the desired colors, direct painting uses opaque colors. After clear coating the pencil drawing, I remasked the background with the AT60 application film. Mixing 1 Shot Tinting Clear, Chamois lettering enamel and turpentine, a prepared a light glaze, which I coated over the drawing. Through the transparent glaze, I still could see the pencil lines, which served as a guide for my painting. Using mixtures of tan and dark brown, I begin building the shadow areas of the cow skull. (See photo #5.) I have the drawing taped next to my panel, which I continually use as a reference.

“I consider myself a copy artist, not a fine artist,” says Bill Riedel. “What I do very well is to copy other works very precisely. If your goal is to realistically reproduce either another painting or a photograph or do someone’s portrait, then you need something to work from.” As his reference, Bill often uses a high quality photograph.

“When you’re working from a photograph, you don’t necessarily need to paint everything you see in the picture, exactly as you see it,” he says. “As an artist you continually make judgments regarding what you are and are not going to include in your painting. If the background is busy, it can distract from the central focal point of your painting. Your painting will be much more effective by cleaning up the background.

“If you paint a portrait, there are some things that you should leave out, such as wrinkles and blemishes. In this type of painting, your goal is to make the subject look good, better than they really look.”

Sal and Bill agree that if you should study your subject matter before painting. While good photography is a tremendous help, additional research is also important. For example, if you decide to paint a skull, particularly a human skull, you may also want to consult an anatomy book. Human skulls have a much more complex structure than what appears at first glance. The cranium alone is comprised of eight bones. And the facial portion of the skull consists of fourteen bones along with 44 teeth.

Photo #5

Plan Your Work. According to master sign painter, Bill Riedel, Sr., take your time to plan your work carefully before you start your project. “Think the job through first, before you jump into it,” Bill says. “Lay the job out. Determine the sequence of steps that you need to take to accomplish the task. Then assemble all of the tools and supplies that you need.”

To some, taking the extra step to plan your work just adds unnecessary production time to a job. Bill, on the other hand, believes that good planning promotes workplace safety, prevents careless mistakes and reduces material waste. He also feels that working systematically and at a more deliberate, more relaxed pace, is less stressful and makes work more professionally satisfying. And when you enjoy what you are doing, he believes that you produce a better finished product for your customer. As you are planning your work, write out a checklist, in order of occurrence, outlining the steps necessary to complete a job.

Building the Highlights & Shadows. In the painting of the cow skull, I gradually built up my shadows and highlights with glazes, starting with a light colored mixture. By using the indirect method of painting one layer over another, you can gradually build up your colors as well as alter your colors and values.

Generally, when someone is using the indirect painting method, he or she starts by painting a very light underpainting. With this as a guide, you can then gradually build the midtones and shadows.

Sal Cabrera says that the indirect painting technique is more time consuming, because you have to wait for the glaze to thoroughly dry before you apply another layer of glaze. In direct painting, you can paint wet on wet. Still he prefers working this way because his paintings are more luminous and have more depth.

Sal says that another advantage of using transparent colors is that they are more forgiving in the sense that you can modify a hue if you don’t like it just by applying another layer of glaze over it.

Everybody has their favorite type of brush and Sal Cabrera is no exception. To apply his glazes, Sal recommends using a “wash” type of brush. For this type of application, other painters prefer using either a filbert or a flat.

Of course, there are many different ways to accomplish a task. Not everybody works light to dark. Some sign painters start by painting a medium value, and then add in the lighter values and shadows.

“Whether I work light to dark or dark to light, depends on the tonal value of the subject that I am painting and what I am trying to accomplish,” Riedel says.

Out of the darkness. If you are working from a photograph, carefully study the lighting. Also
pay attention to any reflected light and reflected colors and determine from which direction the light is coming.

“There’s nothing wrong with using your artistic license and exaggerating the contrast between highlight to shadow in your painting,” says Sal Cabrera. By painting the lighter areas of your work brighter and the shadows even darker, you will create a very dramatic effect. This can make whatever you are painting look much more 3-dimensional.

This technique is nothing new. Called chiaroscuro, Leonardo Da Vinci is credited as its innovator. Baroque painter Carivaggio later perfected the process. Modeling his subjects with light, they emerge from very dark backgrounds. Color, in this painting style, is of secondary importance to lighting.

Finishing Touches. After I was satisfied with the basic painting, it was time to add the finishing touches. My daughter, Lindsay, who has a degree in art and teaches at a local university, suggested using a light glaze of orange, to color areas of reflected light. This gives the illusion that the light reflected off of the background subtly casts it hue on the skull.

I also added some blue tones in the shadow areas. (The finished painting is shown in photo #6.) Cool colors, such as blue, green and purple, tend to retreat or recede into the background. Whereas the warmer colors, such as orange, red and yellow, advance to the foreground.

Photo #6


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