Generally, drawing instruction books and tutors recommend soft pencils (2B, 3B or 4B or even 6B) for sketching and drawing. Hard pencils which include 2H to HB are thought to “damage” the surface of the paper as a result of excessive force (or pressure) and or the hardness of the graphite pencil lead.
The aim of this experiment was to study the approximate force applied (which approximately correlates to pressure = force/area) on the surface of the paper when shading circles with Faber Castell 9000 graphite pencils. This study would allow me to explore the general statements on pressure application on paper during the drawing process. Please note due to the limitation of equipment, this experiment and the findings should be read as approximate or general findings rather than absolute statements.
2.0 . Materials & Methods
Printer Paper (Papyur Rainbow 80 gsm, Fawn colour), Faber Castell 9000 series set (2H-8B), a mechanical pencil sharpener, a pair scissors, digital weighing scales (2 decimal place), purchased from Ebay for 2 euros, calibrated with reference weights), Masking tape, Lab stand (to hold camera/phone during the experiment, IPhone 5 SE (for capturing video footage), Blu Tack (for fixing the digital scales, lab stand), lab gloves, Infrared Thermometer (Broadcare GM320, purchased from Amazon)
2.2 Experimental Setup
I wore gloves to prevent any grease marks or contamination transferring onto the test paper pieces during the experiment.
I cut some rectangular pieces (4 cm x 4.5 cm) of drawing paper (Papyrus Rainbow 80 gsm paper Fawn colour) using a pair of scissors. Then I placed a lid from my Vöslauer mineral water bottle and drew a circle in the middle of the rectangular piece. The resulting circle has a diameter of 3.1 cm, then I fixed the test paper pieced on a small kitchen/jewellers digital weighing scale (2 decimal places) using very narrow strips of masking tape.
The digital scales were also fixed with some Blu Tack to the table top so that it didn’t move during the experiment. The IPhone was held in place with a clamp/lab stand and it was aligned to capture both the test piece fixed on the weighing scale and the display screen.
The Faber Castell 9000 series were brand new, and I sharpened them using my mechanical pencil prior to the experiment.
2.3 Running the experiment
I checked the surface temperature of the paper piece using my infrared thermometer, before and after shading.
I began capturing the video footage prior to shading the circle on the test piece. During the experiment, I was trying not to look at the digital display and I tried using my personal judgement to apply even pressure while shading the circle.
All test pieces were shaded in one sitting, to avoid changes in humidity or room temperature.
2.4 Data collection
The video captured from these experiments were played back at a slower speed and I transferred the data time vs weight in a spread sheet (Numbers on my Imac). I took an average of 3 readings.
3.0 Observations and Results:
The humidity and room temperature did not vary during the experiment. I plotted weight (gram) against time (second) for each experiment undertaken, and this is shown in Figure 1.
During the experiment, I was fairly convinced that I was applying similar pressure while shading. But it is clear from the graph, that may be misleading. For all grades of pencils, weight increases as a function of time, this is perhaps due to the fact that the pencil is gradually moving towards me so this results in more force applied to the paper.
I will conduct another experiment in which I will shade the circle in the reverse direction to prove or disprove my hypothesis.
Interestingly, I applied less pressure onto the paper when I was shading with harder pencils. What was interesting however, was with the softer pencils 2B onwards where I was really struggling to apply less force on the paper with my pencils. With very soft pencils the pencil felt like it was floating on the paper but the graph shows that the force (ie, the weight) applied was about the same if not more.
Assuming that using my personal judgement (or perception) I applied the same weight (or force or pressure) while shading the circles with pencils with varying hardness. My findings so far are as follows:
Hard pencils may damage the paper because of the hardness of the pencil lead rather than the perception/feeling of applying higher force or pressure.
I perceived that I applied less force or pressure while shading with softer pencils, but the graph shows that I may have applied more force on to the paper. This perception is perhaps due to the fact that the graphite easily transfers onto the paper surface, the feeling is like melting butter on a piece of toast. This encouraged me to easily drag my pencil across the paper.
Drawing with softer pencils actually may indicate that higher pressure is applied on the paper surface compared to shading with harder pencils.
5.0 Future Work
I will repeat the experiment with different drawing papers, primarily Fabriano Artistico Hot Press.
I will also report my observations of these test pieces when I study them under my usb microscope and I will measure the intensities of the graphite laid on the test pieces using my IR spectrometer soon.
I would like to thank Faber Castell for their permission (E-mail correspondence with Herr. Holger Unfried, Product Manager, A. W. Faber Castell Vertrieb GmbH) to share my experimental work freely.