In this study, I examine how various graphite pencils and graphite sticks build up on drawing paper (Fabriano Accademia 200 gsm) using a simple usb microscope (magnified images) and a Near Infrared Spectrometer. Graphite 002 study is focused on Faber Castell 9000 series and graphite sticks. Future posts will cover other brands.
2.0 Materials & Methods
Graphite Pencils: Faber Castell 9000 set (2H to 8B, vegan-friendly)
Graphite sticks: Faber Castell Graphite Jumbo (2B)
Clutch Pencil: Faber Castell TK9400 (2B)
Paper: Fabriano Accademia Paper (200 gsm, vegan-friendly). The paper was fixed to a wooden board (30 x 42 cm, A3 size) as discussed my previous post in Mounting paper using staples.
Miscellaneous: A lid from Vöslauer Mineral Water bottle with an inner diameter of 3.1 cm was used to draw circles on the paper. A sheet of generic printer paper was used during the shading of the circles to avoid transferring any graphite from the test area to the surround paper surface. A tissue roll for blending the graphite layer prior to taking measurements with my Near-IR spectrometer. A Lab Stand with a clamp was used to hold the USB microscope or the LinkSquare Spectrometer. A mechanical pencil sharpener (Fig. 2b) was used to sharpen the pencils. An IPad Pro (12.9 inch, 2017 model) or an IPhone 5SE was used to take photos of the paper surface before and after shading.
2.2 Instruments & Software
Instruments: A generic no-brand USB microscope connected to an iMac, Infrared Thermometer (Broadcare GM320, purchased from Amazon), Linksquare Near Infrared spectrometer (Stratio Inc., website: https://linksquare.io/)
Software: USB microscope images were captured using PhotoBooth (MacOS native app), LSCollector (Stratio Inc., version 1.0.2) was used to collect the data from LinkSquare Spectrometer.
Step 1: Preparation of Work Area
I purchased a roll of Fabriano Accademia Paper (1.4 m x 10 m) from a local Art supplies store in Vienna, Austria. A large sheet was cut from the paper roll and using the method previously outlined (link here) I fixed the paper to a wooden board using staples. I allowed the paper to dry for at least 9 hours prior to drawing or shading. I rotated the board several times during the initial first hour to reduce one side becoming more hydrated and to stop any water pooling on the edges. The paper was allowed to dry at 25°C (room temperature regulated throughout this study). I checked the temperature using the hand held infrared thermometer at random times, and it remained constant. The resultant paper surface felt completely smooth and dry, shown in Figure 1.
Step 2: Shading circles
Using the lid (inner diameter of 3.1 cm), from my mineral bottle water (Vöslauer 1L) as a template, I drew circles on the paper surface using various graphite pencils and sticks listed in the Materials section (see Figure 2a). I applied diagonal shading in the circles using a “perceived” (see my discussion in Graphite Study 001) uniform pressure. Overall, the circles appear uniformly shaded (Figure 2b).
Step 3: Examining the paper surface using a generic USB microscope
The USB microscope was clamped on a Lab Stand to keep the height and setting consistent throughout this experiment. The magnification was set at least 20x (unfortunately I lost the printed calibration card, but that’s my minimum setting on the usb microscope). I will redo this experiment in the future with a calibration ruler. I connected the USB microscope to my iMac and used the in-built PhotoBooth app to capture the images. I chose an area within the circle with homogenous shading. For blending I used a fresh piece of tissue each time and very lightly rubbed the area with it. I captured images before and after blend the circle.
Step 4: Acquisition of Visible and Near-IR spectra
Prior to taking the measurements with the spectrometer I blended the circles using a piece of tissue paper as described previously in Step 3.
I clamped the LinkSquare Near-IR spectrometer in a Lab Stand. The distance between the spectrometer and paper was approximately 0.75 cm. I used the test cards which came with the instrument and collected the data. I will use this data as my standard calibration data and note any variations in future experiments. The spectrometer was connected to my iMac running LScollector (Stratio Inc., version 1.0.2) and the data was collected. Both LED + Bulb were selected. Absorbance or intensities are measured as a function wavelength (range from 400-1000 nm). So far I have not processed the data but I will only show selected spectra collected without fixing the baseline. I have exported the raw data exported into Excel but I will come to this part in another blog post.
3.0 Results & Discussion
The circles appear darker with softer pencils (3B onwards) for Lyra, Brand Y (permission pending) and Faber Castell graphite implements as shown in Figure 2b. Looking closely at the shaded circles (Faber Castell 9000, graphite stick) using a generic handheld microscope (method detailed in Section 2.3, Step B) shows how graphite adheres to the paper. The images are shown below in Figure 3-14.
Figure 3: Faber Castell 9000 pencil grade 2H: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 4: Faber Castell 9000 pencil grade H: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 5: Faber Castell 9000 pencil grade F: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 6: Faber Castell 9000 pencil grade HB: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 7: Faber Castell 9000 pencil grade B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 8: Faber Castell 9000 pencil grade 2B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 9: Faber Castell 9000 pencil grade 3B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 10: Faber Castell 9000 pencil grade 4B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 11: Faber Castell 9000 pencil grade 5B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 12: Faber Castell 9000 pencil grade 6B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 13: Faber Castell 9000 pencil grade 7B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
Figure 14: Faber Castell 9000 pencil grade 8B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (top), blended (bottom)
These results (Figure 3-5) show that shading with harder pencils (grades 2H, H & F) yields a more uniform layer both blended and unblended. I can also see that the particles or graphite clusters on paper appear to be smaller. It is possible that the smaller graphite particles enter the smaller valleys and dips in the paper giving a more homogenous-looking layer. As the pencil grade becomes softer it is clear the graphite particles or clusters become larger. When I blended the shaded circles there was a fair amount of graphite on the tissue paper which shows on the blended circles. For softer pencils (4B-8B) the effect of blending is more pronounced as shown in Figure 10-14, the large graphite clusters are broken down and spread across the surface of the paper. It is notable that shading with softer pencils shows a fair amount of white paper before blending.
Figure 15 (a-b): Preliminary results from the LinkSquare Spectrometer. The data from this will be processed in Excel at a later date.
The results from the spectrometer show that with both sources of illumination (LED and Bulb, these light sources cover different ranges of the wavelength spectrum) the intensities of the shaded circles sharply drop as a function of the softness of pencil (more graphite or larger graphite particles). This confirms the visual images seen under the usb microscope (Figure 3-14). The x-axis in the Figure 15 is unfortunately not linear, but I will process this at a later date. But for this discussion it doesn’t really matter too much as these are comparative or relative results. What is interesting is that in Figure 15b, where the illumination source was a bulb (encased in the spectrometer) the difference in the intensities between 2H and HB is very large. I will investigate this point in the future.
Here are the results comparing various 2B graphite implements: Faber Castell 9000 2B (previously shown in Figure 8) vs Faber Castell Jumbo Graphite crayon or stick (2B) vs Faber Castell TK9400 clutch pencil (2B).
Figure 16a: Faber Castell 9000 pencil grade 2B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (same as Figure 8)
Figure 16b: Faber Castell Jumbo Graphite 2B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended (same as Figure 8)
Figure 16c: Faber Castell TK9400 (clutch pencil) 2B: Shaded circle unblended (LHS), 30x magnification (RHS) unblended
The magnified images of the various 2B pencils and graphite crayon in Figure 16a-c, show that although there are subtle differences in the shaded circles (LHS in Figures) the content of the graphite particles seems fairly similar. I thought that there would be some difference as the circle shaded with the graphite stick seems slightly darker.
Here are the spectra of various 2B graphite implements (produced by Faber Castell) on Fabriano Accademia drawing paper (200 gsm), shown in Figure 17.
The spectrometer was able to pick up the minor difference in shading between the 2B pencils. Slightly lower intensities were measured for the graphite stick 2B as it is visually apparent from the shaded circles (compare LHS images in Figure 16b vs Figure 16a and Figure 16c.).
4.0 Future Work
I will be undertaking a more detailed analysis of the spectra measured using LinkSquare for the Faber Castell 9000 and other graphite implements. I already have the studies for Lyra pencils and another brand (lets call it Y as the company would like to see my studies first before granting me permission to publish them on my website). I will also undertake similar work in the future on other drawing papers I have.
5.0 Permissions & Acknowledgements
I would like to thank Fabriano (E-mail correspondence with Giuseppe Prezioso, Marketing Fabriano, Italy) and Faber Castell (E-mail correspondence with Herr. Holger Unfried, Product Manager, A. W. Faber Castell Vertrieb GmbH) for their permission to show my studies. Stratio Inc. clarified that I retain ownership of the data collected from the spectrometer. I have already signed an NDA with Stratio Inc. which has allowed me access to some information which I require for processing my data in Excel. Although for this post, only raw data is shown. Please note that I purchased all the art materials and I am not sponsored by any company or university.