Rendering Glass with Charcoal and Pastel

One of the more challenging subjects that my students seem to encounter in my still life drawing class is the rendering of glass. I would be lying if I said that this isn’t a challenge for me as well. Glass can be a tremendously complex subject to tackle due to the variants of value tone and color caused by reflections, transparencies and high-lights, not to mention surface details such as stains or scratches on the glass. It is tough to know where to begin when confronted with so much information. Below, I have documented the progress of one of my own still life’s which deals with some elaborate reflections in a glass jug.  One of the first things I’d like to stress, is that it is important for one to establish a fixed point of view each time they observe their subject. This applies to any drawing that is being done from life, but it is especially important with glass. The slightest movement of your head can drastically change every reflection that you see.  Also, remember that anything behind the glass will be visible to some degree.  Keeping the background simple (even a solid color) is a good rule of thumb for a beginner.  In the example below, I have chosen a coarsely textured background which provided a slight challenge but it was still relatively uniform in color and value. This made it easier to distinguish which tonal sections were caused by transparencies, high-lights, etc., and this leads me to the last topic I’d like to touch on – the importance of good lighting.  Multiple light sources will create more reflected light, so try to keep it simple. I recommend using one direct light source. This will provide strong high-lights, which will contrast nicely against the transparency of the glass, particularly if using a dark background.

I’ve chosen to render my subject on toned paper. Because the subject is so dark with limited high-lights, I chose a paper that was just a tad darker than a mid-tone. If the background had been light, I may have chosen a lighter gray or even a white sheet of paper. If the background had been black, I could have gone even darker with my paper tone. The paper here is essentially acting as a toned ground would in a painting. The materials I used for this drawing were white & black General’s charcoal pencils (initially this was all I was going to use, but I so much enjoyed the cool green tint of the glass that I decided to add color at a later stage) soft pastel sticks, pastel pencils, blending brushes and tortillions


Example A

Step 1.

After establishing the general shapes in line with my black charcoal pencil, I put the strongest lights in with my white pencil. After this step, the gray paper read much darker and made it easier to gauge my darker tones in the subject. While squinting, (I always do this in the beginning because it eliminates unnecessary detail and makes it easier to observe only the most obvious shapes) I blocked in the darkest shapes using a compressed charcoal stick as seen in the middle portion of the jug in example A. I made sure not to press too hard in order to understate my value. I can’t stress enough how important it is to keep values light in this stage. Once you go too dark, it is very hard to go backwards. I then began blending my tones into the paper with a relatively stiff flat brush in order to smooth out my gradations


Step 2.

After establishing a good variety of darker value shapes, I was now ready to increase my tonal range by adding more white over my gray tones as seen on the right edge of the bottle next to the high-light in example B. This is something that I usually caution my students against if they are choosing to work in only black and white charcoal. Blending the two mediums together creates a cool bluish-gray value which differs from the gray tone of the paper. Once one has acquired some knowledge of warm & cool grays as they apply to light and form, this type of blending technique can add depth and limited chroma to a black & white drawing. I could have continued rendering the bottle like this and it would have held up just fine as a black & white image, but my desire to explore more subtle warm and cool relationships led me to the following step(s).


Example C.

Step 3.

There was a unified blue-green tint to the glass and I simply couldn’t resist adding some of that color with my soft pastel sticks as seen in example C. The wonderful thing about pastel is that it can be opaque or transparent depending on how heavily it is applied. As I began adding color I was able to allow some of the grays in my previous layer to show through which ultimately added more depth to the drawing. This step is similar to glazing over a grisaille in oil paint. I stuck to about three shades of green. The degree to which I was able increase my color range was achieved through careful layering. I’ve never encountered much of a problem with the charcoal smearing or blending into the pastel, but if that is a concern, the black & white rendering can be completed and sprayed with a fixative prior to adding color. As I continued working with the pastels, I periodically smoothed out sections of color with blending brushes before adding more color. Sometimes the pastel can become very chalky and particles have to be brushed off the paper before it will accept additional layers.

jug 4

Example D.

Step 4.

At this stage I continued working more subtleties and detail into the drawing and I spent a great deal of time evaluating all of my value and color relationships. I began to slowly increase my palette with black, blue, green, purple and brown variations of color. I also began to gradually darken sections. As I continued to explore these subtle variations, I kept in mind that I still needed my value tone to remain somewhat unified. It was  hard for me to judge exactly how much darker I needed to push my values without a background tone, so, with my black pastel stick, I roughly applied a dark, bold tone to the right side of the jug as seen in example D. After taking a moment to evaluate, I decided that this tone was a bit too dark as it didn’t match up with the transparent sections in the bottle. I knew however that that could be easily corrected by blending in some lighter opaque tones with my pastels, and so I continued to rough in the darker tone as a base. I then completely smoothed it out with a wide, flat blending brush so that it would be ready to accept additional layers.

Empty jug3

Example E.

Step 5.

I finished up the background by working in lighter variations of value and color with pastel sticks and pastel pencils. As I did this, I attempted to depict a stucco wall texture which I thought contrasted nicely against the smooth shading in the glass. This process was very time consuming. Once the background was near completion, I re-worked some of the value gradations in the jug, making sure that they closely matched the tones of the stucco wall. I then brought all of the surrounding areas up to completion.

Overall I am pretty satisfied with the result. If I were to do it again however, I would work up the background first.  That would have made gauging my value tone in the glass a little easier. One of the things that I love most about pastel is its range of color. It can be bright and bold or extremely subdued and nuanced.  I often will use pastel as a medium to work out studies for oil paintings, but it can also be used to create a finished rendering which stands on its own as I’ve done here. I wouldn’t use it as a substitute for oil, but it is a great medium to try for anyone interested in making the transition from drawing to painting. No other drawing medium offers the same qualities. It is also less time consuming than oil painting which is an added benefit.

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