An Artist's Guide to Pastel Colours

by Paul Centore

© Sept. 20, 2015 (launched Aug. 30, 2014)


Most pastel manufacturers produce hundreds of pastels, covering a wide variety of colours. Pastel painters need some way to make sense of such a broad array. One natural approach, that has been used here, is to organize pastels in terms of the Munsell system. Munsell specifications were found for the following pastel sets:

Pastels with Munsell Specifications
Brand Number Of Pastels
Great American 546
Sennelier 525
Unison 422
Mount Vision 407
Schmincke 400
Blue Earth 336
Girault 300
Rembrandt 218
Total 3154

Finding Munsell Specifications for Pastels

The first step in finding the Munsell specifications is making samples of the individual pastels. A sample is just a square (about an inch on each side) of colour, in an opaque layer, made by applying a particular pastel to paper; it is the colour a painter will get when he uses that pastel. Here is a sheet of samples of some Rembrandt pastels:


Samples of Rembrandt Pastels

The reflectance spectra of the samples are then measured with a spectrophotometer. The picture below shows the X-Rite i1Pro2 spectrophotometer that was used to measure the Rembrandt samples:


i1Pro2 Spectrophotometer Measuring Rembrandt Samples

A pastel's Munsell specification can be calculated once the pastel is measured. Such specifications were calculated for all 3154 pastels, and are available in the files PastelData.xls or PastelData.ods. The files contain multiple spreadsheets. Here are a few lines from the spreadsheet "Munsell," listing the pastels of highest chroma. The rest of the spreadsheet lists Munsell data for the other 3150 pastels.

Section of Munsell Spreadsheet

In addition, the spreadsheet "MunsellToPastel" lists the pastels which are closest to a standard Munsell specification. The sample line below shows two pastels (#328 from the Girault line, and #034O from the Schmincke line) which are the closest matches for the colour 7.5RP 5/8. The spreadsheet contains such a line for the 2,745 standard Munsell colours, listing the five pastels which are the best matches for that colour.

Section of MunsellToPastel Spreadsheet

An artist with a Munsell reference can use this data to make purchasing decisions, rather than relying on questionable colour reproductions in catalogs.

The measurement project provided some interesting results. For example, some examples were found in which two pastels with the same name, from the same manufacturer, were slightly, and occasionally exceptionally, different. Here are two examples:

Two Versions of Rembrandt 331,9 Two Versions of Sennelier 303
Two Versions of Rembrandt 331,9 Two Versions of Sennelier 303

Another surprising finding was that many pastel brands had a fair number of near-duplicates, that is, two pastels whose colours were practically identical. Here is an example of some near-duplicates of Rembrandt pastels:

Some Duplicates in Rembrandt Pastels
Some Duplicates in Rembrandt Pastels

These results and others are presented in detail in Pastels: A Colour Guide For Artists and Manufacturers. A more technical discussion of the pastel gamut is given in A Colour Survey of Artist's Pastels.

Currently, this analysis has only been applied to the eight brands listed. It would be desirable for painters to extend this analysis to other pastel brands, to give more comprehensive results, and comparisons between manufacturers. The current bottleneck is obtaining samples. While the author owns several hundred pastels from many brands, he has no complete line from any one brand. Other pastel artists, who do have complete sets, are invited to contribute to further pastel analysis by sending the author samples, which he can measure and analyze.

The samples should meet the following conditions:
1. Each sample should be at least half an inch (or 1.5 centimeters) by half an inch,
2. The samples should be applied to a standard pastel paper. White Canson Mi-Teintes paper is adequate, but sanded papers, such as Wallis or Sennelier LaCarte, work well, too,
3. The pastels should be applied thickly enough that the samples are opaque. When in doubt, add more pastel to a sample. Ideally, it should be impossible to discern the colour of the paper through the pastel sample,
4. The surface of the samples should be reasonably smooth, with no obvious irregularities. Rubbing the pastel with a finger produces a sufficient finish,
5. The samples should be clearly labelled, using the pastel manufacturer's naming convention,
6. Do not use any fixative, as this can alter colours. A protective sheet of Glassine can be used over each sheet of samples, to keep the pastel from rubbing off, and
7. There is no problem using a large number of smaller sheets (say 8.5 by 11 inches), for easier shipping.

Once the samples are prepared, they can be mailed to the author, Paul Centore, at 62 Chicago Ave., Groton, Connecticut 06340, USA, who will measure them and post results on his website. Artists should be aware that preparing samples can be considerably more time-consuming and tedious than it seems, especially since it is important to produce a thick, opaque layer. An entire set of samples can take eight hours or more, depending on the number of pastels.

Apart from artists, pastel manufacturers are also invited to send samples of their lines. If the preparation process is too tedious, then the manufacturer can send a complete set of pastels to the author, who will prepare the samples himself, and generate a report. In addition to providing some exposure, the report might also be helpful at identifying unexpected duplicates, or gaps in gamut coverage, that can be used for revision and development of the pastel line.



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Colour Analysis of Pastels
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