Add Depth to Your Quilt Designs with Effective Transparencies

The Many Ways to Add the Illusion of Depth to Your Work

One of the most challenging aspects of working in a two-dimensional medium like quilting is creating the illusion of three dimensions or depth. Depth creates a strong sense of reality in the work, as well as adding elements of high drama and visual interest.

As quiltmakers, we have many ways to add depth to our work. Here are a few examples:

Linear perspective. If landscape quilting is your passion, designing your quilt around a vanishing point is an effective way to create depth.

Focus, texture, and detail. Objects that include more detail and texture appear closer, while those with less details and smoother textures are perceived as being more distant.

Layering and overlapping. Placing one or more elements in front of another creates the illusion of depth. When the illusion of transparency is added to these overlapping objects, your work can take on added dimension.

It is this illusion of layering and overlapping elements to create transparencies that I’d like to explore in this article.  

Sifting Through the Research

Experts in visual perception have studied the phenomenon of transparency for years. As I read through the studies, I found my head spinning with terms like single reversing X-junctions, rotating episcotisters, and constraints of Talbot’s law. Yikes!

I hope to spare you the brain strain by selecting a few of what I considered to be the most compelling ideas from the research on transparency, as well as what some of the great art educators of our time have said about it. My goal is to help you understand how you can apply several powerful cues pertaining to alignment, a compelling “middle mixture”, and depth order to enhance your own work.

Researchers View Versus the Artist’s View

Since there is no accurate way to mechanically measure the illusion of transparency, researchers typically base their studies on responses from actual people who view examples of transparency. These participants are asked to judge whether various images conveyed transparency, and if so, how strongly. 

Interestingly, the great 20^th century artist and educator Josef Albers had different opinions about effective transparencies. That difference of opinion made me realize that an important part of our work as artists is to find new ways to portray the world. Our work doesn’t necessarily have to be constrained by visual laws and rules defined by researchers. 

In fact, the research suggests that artists have been far ahead of science in using our unique visual languages to express new, as-yet-untested principles. Therefore, the ideas below are just starting points. Once you know the rules, I encourage you to break them to suit your own artistic purposes!

A Few Definitions

Let’s start with a few basic definitions:

• A transparent material transmits light to some extent so that light arriving on one side can be seen from the other side. 
• An opaque material does not allow any light to pass through it. It’s non-transparent. 

An effective transparency, therefore, is created when an artist creates the realistic illusion that light reflected by one object is travelling through another object. Our challenge as quiltmakers is to create this illusion using opaque (non-transparent) materials.

Let’s talk now about three cues that we can use to achieve the illusion of transparency.

Cue #1: Alignment

Proper alignment of the “overlapping” area is important to depicting transparency. Take a look at the first two images below. Both depict four distinct areas: two background areas (black and white) and two half-disc shapes (medium gray and light gray) overlapping the background areas. 

Image 1 shows the two half-discs aligning perfectly with one another along the boundary line between the two background areas. The two points at which the background areas and the half-discs intersect are called X-junctions. I’ve highlighted the X-junctions in this example in bright pink. The X-junctions are intact, and therefore depict a realistic transparency.

Look at Image 2. You see the same four elements as above, with one major exception: the half-discs appear to have slipped apart. Do you see how their X-junctions have been broken? The broken X-junctions diminishes (if not eliminates) the perception of transparency. The impression we now have is of two opaque half-discs covering the background areas.

Here’s another example. Image 3 shows four areas: a white background, a dark square, a light square, and a medium-light square. Do you see how their X-junctions align beautifully? This is an example of credible transparency.

Image 4 shows the same four elements as in Image 3 with one major difference: the overlapping area no longer aligns with the boundaries of the light square along the X-junctions. These broken X-junctions destroy the perception of transparency. What we perceive instead is an opaque middle mixture overlapping two opaque squares with no transparency.

What does this mean for quiltmakers? To create a convincing illusion of transparency, we need to be sure to accurately match our seams at these X-junctions (the point at which all four areas – background, light square, dark square, and middle mixture – intersect), otherwise the illusion will be reduced or destroyed.

Image 5 shows how this configuration might be pieced together as a quilt block. The X-junctions highlighted below show the places you’ll want to be particularly careful about matching your seams to preserve the illusion of transparency.

Exceptions to the Alignment Rule: Refractive Materials

Are there exceptions to this rule of alignment? Yes! The depiction of clear water or other materials that refract light don’t require precise alignment. 

The term refraction refers to the change in direction of light as it passes from one medium to another. Water, glass, prisms, diamonds, and other gemstones all refract light to some degree; they bend light as it passes from one material to another. If your goal is to depict any of these materials accurately, you don’t want to perfectly align the objects. Doing so might confuse your viewers.

Cue #2: “Middle Mixture”

The second cue to transparency involves the overlapping area, otherwise known as the “middle mixture”. It’s relatively easy to create transparencies as a painter. Choose two pigments and blend them to create the “middle mixture”. However, it’s not so easy when using solid fabric.

Researchers separate different types of mixture configurations into two groups: unambiguous transparency (i.e., credible), and ambiguous transparency (i.e., less credible).

Unambiguous Transparency

Images 7 and 8 show examples of what researchers call “unambiguous transparency”. These are configurations that research participants perceived as very credible transparencies. Image 7 shows two blue squares – one light in value and one dark in value – with a middle mixture of a medium value. Image 8 shows two squares – one blue and one yellow – with a green middle mixture.

Why did people think these were the most credible depictions of transparency? Researchers discovered that the most realistic transparency is achieved by finding a middle mixture that has a value that is between the values of the other two squares. In other words, if one observes a light square and a dark square, the “overlapping” area should be a medium value.

We can apply this same concept of an “in-between” middle mixture when we look at squares of different hues. Image 8 depicts a blue square, a yellow square, and a green middle mixture. If you consult your color wheel, you’ll find that green is between blue and yellow, making this an unambiguous transparency. 

Ambiguous Transparency

Image 9 depicts two main squares of equal light value with a middle mixture that has a darker value. Image 10 depicts two main squares of dark value with a light middle mixture. According to researchers, study participants indicated that Images 9 and 10 did not show strong transparency. They perceived an ambiguous transparency. 

Participants indicated that both main squares in Image 9 appeared to be transparent, but they could not determine which one was “on top”, therefore, the perception of transparency was weakened. As for Image 10, participants saw no transparency. Instead, they indicated that they saw three opaque shapes: a white opaque square overlapping two dark opaque squares. 

As an artist, I see transparency in both Images 9 and 10 even though they might not be as strong as Images 7 and 8. The great art educator Josef Albers would have as well. In fact, Albers has a term for the middle mixtures that create the type of transparencies found in Images 9 and 10: subtractive mixture and additive mixture. 

Subtractive and Additive Mixtures

In his book Interaction of Color (Yale University Press; 1963), Josef Albers confirms that the type of transparencies illustrated in Images 9 and 10 are indeed credible. He termed them subtractive and additive mixtures.

Subtractive mixtures result in the subtraction of light from the overlapping area. In other words, the middle mixture is darker than the two main areas around it. Albers reminds us that this type of mixture is the realm of the painter. Any artist who has mixed two pigments and ended up with a darker hue understands subtraction mixtures.

Additive mixtures result in the addition of light to the overlapping area. In other words, the middle mixture is lighter than the two main areas around it. Albers considers this type of mixture to be in the realm of the physicist. Lighting engineers know this effect well. When different colors of light are focused on a single spot, the result is pure white light. 

What’s the Best Type of Middle Mixture to Use?

As far as researchers are concerned, you can’t go wrong creating an unambiguous middle mixture – one that has a value or hue that is between the two main areas. Those are the most credible, realistic type of transparency, according to research participants. 

However, Josef Albers shows us that middle mixtures that break this rule – namely, subtractive and additive mixtures – can also be used effectively as transparencies.

My advice? Use the type of transparency that best serves the purpose of your art. If your goal is to render a realistic landscape, an unambiguous transparency (i.e., creating a middle mixture that is in-between two other “overlapping” areas either in value or hue) is probably your best approach. However, more abstract work can benefit from the use of more ambiguous transparency that incorporate either subtractive or additive mixtures.

Cue #3: Depth Order 

To achieve credible or unambiguous transparency, you need at least two materials in which one is clearly in front and one is behind. In other words, you need to create an illusion of depth order.

Consider Image 11. This image depicts three gray horizontal bars intersecting a light yellow vertical panel. Which of the gray bars appears to be “in front” of the light vertical panel? Which one appears to be “behind” the panel?

Careful examination of Image 11 reveals that the dark olive background, the light yellow vertical panel, and the dark gray tabs on either side of the vertical light yellow panel are solid colors. The only variable in the image are the light, medium, and dark horizontal bars intersecting the light yellow panel.

The lower gray bar appears to lay on top of the light yellow panel, while the upper gray bar clearly appears to lie behind the panel. The middle is somewhat more difficult to assess its depth order. How is this illusion achieved?

Let’s add more context to this image. I’ve labeled the light yellow panel with the value of “A”. I’ve also labeled the dark gray tabs on either side of the panel as “B”. Finally, I’ve labeled the intersecting gray bars as “C”. 

Here’s the key: when C most closely resembles A, A is seen to be “on top”. When C most closely resembles B, B is seen to be “on top”. 

In Image 11, the upper gray bar is lighter than the other two intersecting gray bars. In other words, the value of the C area more closely resembles the A panel than the darker B tab. Therefore, the light yellow panel (A) appears to overlay the dark gray bar.

Now look at the lower gray bar. The value of the C area more closely resembles the darker B tab than the light yellow A panel. Therefore, the dark gray bar (B) appears to overlay the light yellow panel.

The middle horizontal gray bar could be seen as on top or underneath. That’s because it is half-way between the value of  A and B. 

Now consider Images 12 and 13. In Image 12, we have two areas – one blue and one green – with a middle mixture of a greenish-blue (i.e., the area is primarily blue with a hint of green). In Image 13, we have the same two areas of blue and green, but the middle mixture is bluish-green (i.e., the area is primarily green with a hint of blue). 

In your opinion, which square is on top in Image 12, and which one is on top in Image 13? 

In Image 12, it appears that the blue square is on top, because the middle mixture has more blue in it and so more closely resembles the blue square. In Image 13, the green square appears to be on top, because the middle mixture has more green in it and therefore more closely resembles the green square.

To state this principle in the words of the researchers, the overlapping region tends to be seen as the continuation of the region from which it deviates least in value or hue.  

Playing With Transparency

Exercise #1: In your opinion, which of the two images below display a stronger transparency? Why? (Hint: consider the alignment.)

Exercise #2: In your opinion, which of the two rectangles below appear to be on top? Why? (Hint: which of the triangles does the middle mixture most closely resemble?)

• Find a large white (or very light) square to use as your background. 
• Next, find two solid fabrics in your stash that are different values of the same hue. For example, you might select a light pink and a bright red. Cut 6” squares from each fabric.
• Overlap the two fabrics on your background so that the overlapping area is about 2” square.
• Find three solid fabrics of a value in between the two larger squares to create the “middle mixture” (i.e., medium pink, dark pink, dark red). Cut 2” squares from these fabrics to perfectly fit the overlapping area.
• Depending on the middle mixture fabric, which of the large squares appears to be on top? 

Conclusion

I hope this has given you a new perspective on how to add depth to your quilts by creating powerful transparencies. In next week’s article, we’ll explore the amazing ways color can change just by pairing it with a different neighboring color. Until then, be well and shine on!