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Hidden in Plain Sight: The Hidden Images Underneath the Painting

There is a centuries-old technique used by the Renaissance masters in works from Leonardo da Vinci's Mona Lisa to Michelangelo’s Sistine Chapel, and it's hidden just beneath the surface.

Painting of colorful ranunculus flowers by Raleigh artist Katie Pena
The underpainting adds vibrancy to these colorful flowers inspired by my wedding bouquet!

Just like in the style of the masters, my oil portrait process begins with a sketch, and is followed by an underpainting. I then proceed with the traditional Renaissance techniques of using glaze layers to add depth and color to the painting. Today, modern X-rays can be used to see through the paint of some of the most famous paintings in the world to the underpainting beneath the layers. The process often reveals changes to the artist's initial design or even alternate paintings that have been covered up entirely!

What is an Underpainting?

Green underpainting visible on unfinished oil painting of a cortado by Raleigh Artist Katie Pena.

An Underpainting sort of functions as the the scaffold for an oil painting. If the initial pencil sketch is the skeleton, then the underpainting is the ligament and muscular structure of the painting. After the basic values of light and shadow are locked in during this phase, the ‘hair/skin/nails/superficial detail elements’ of the painting are applied as glaze layers of color that are true to what the viewer’s eye sees of the reference image at a quick glance. 

I use a combination of 2 methods that have been used by painters since at least the Renaissance era: Verdaccio and Bistre. These are some of the same techniques that were used to paint Michelangelo’s Sistine Chapel. 

Verdaccio and Bistre underpainting techniques in unfinished portrait of happy couple by Raleigh artist Katie Pena

Verdaccio is applied to the areas that contain a human figure— the reason this works is similar to photo negatives you’ve probably seen back when film cameras were more commonly used. When the negative was held up to the light, the colors would always be inverted- and we’d see a greenish color wherever fleshy pink tones would result in the final printed photo. 

Green is a complementary color to flesh tones, and therefore adds depth to an oil painting that is completed in a series of glaze layers. When complementary colors are mixed together, they neutralize each other and can create a shadow tone. 

Bistre underpainting visible in unfinished pet portrait of dog with large ears by Raleigh artist Katie Pena

Bistre on the other hand, is a similar principle but using opposite tones. I like to use this method (not to be confused with the actual pigment with the same name) to create luminosity and the illusion of atmospheric distance in a landscape. 

Again, I use a complementary color to create more depth in this area- and most landscapes are comprised of blues and greens, hence why the rich reddish brown tones in this method are established as a foundation, prior to the addition of more colors with more layers. 

For both techniques, while they are still wet, I quickly wipe away the brightest areas (such as sky or shiny highlight reflections that I want to appear almost pure white). With this as my foundation, I have established luminosity that will radiate through the glaze layers of color that will come next. 

You can see more examples where I have used techniques like these, in addition to others like Grisailles, on my Instagram account. 

Interested in working with Katie?


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