Tuesday, August 31, 2010

A Lightfastness Standard for Pastels: current status

This post is about the progress to date in developing a lightfastness standard for Soft Pastels.  It highlights how pastel artists can get involved
Unison - Yellow Green Earth Pastels

Recently in the Pastel Talk Forum over on Wet Canvas there has been a thread discussing the lightfastness of NuPastels - see Re: Nupastels (archival / lightfast?).  The discussion was proceeding with no reference to the current lack of a lightfastness standard for soft pastels - so I highlighted this issue as follows
So far as I am aware Pastels are one of the few art media without an ASTM standard relating to lightfastness

Thus we have........

ASTM D5383 - 02(2010) Standard Practice for Visual Determination of the Lightfastness of Art Materials by Art Technologists details the technique to be used for artists paints

ASTM D4302 - 05 Standard Specification for Artists' Oil, Resin-Oil, and Alkyd Paints

ASTM D 5098, Specification for Artists’ Acrylic Emulsion Paints

ASTM D5067 -05 Standard Specification for Artists' Watercolor Paints

ASTM D5724 -06 Standard Specification for Gouache Paints

ASTM D6901 - 06 Standard Specification for Artists' Colored Pencils details the standard for coloured pencils - which, in turn, has resulted in a lot of development in terms of lightfast pencils. They've not got it right yet but if turn up the heat in terms of exposing pencils that don't make the grade you can expect to see them withdrawn from sale! I saw the blue wool tests for some of the pencils that CPSA tested and it was utterly shameful what some of the manufacturers were doing in terms of selling pencils which were in no way lightfast. The excuse of course was that for years they were sold for illustration work and since that was photographed and/or put away in dark drawers there was no incentive to create lightfast pencils

and absolutely NOTHING for pastels

except maybe ASTM D4303 -10 Standard Test Methods for Lightfastness of Colorants Used in Artists' Materials ?

The Coloured Pencils standard was achieved through the initiative of the Colored Pencil Society of America - but I've never heard of whether or any of the Pastel Societies have tackled this thorny topic.
Subsequently there were responses indicating what I'd heard - that a lightfastness standard for soft pastels was in development.

ASTM Lightfastness Standard - an update

This is what Maggie Price, President, International Association of Pastel Societies had to say
You are correct but a standard is being developed by ASTM. It has been in the works for a year or more and hopefully will be completed within another year. It is a long and arduous process of testing for lightfastness and safety, and many of the people on the committee are volunteers. IAPS has a representative on the committee that is discussing the standards for pastels.
This response by Michael Skalka, the current Chair, ASTM D01.57 Artists’ Materials was particularly illuminating! I've written to him and also reproduced his response in the forum below for the education of all pastel artists - and as an invite to get involved! :)

I've highlighted in bold what I think are the MUST READ parts in his statement below.
I hope I can shed some light on the discussion of lightfastness, ASTM and related issues that have been brought up. Let me briefly go over the thread and comment on some of the issues.

No lightfastness standard from ASTM exists yet. Manufacturers, not consumers, have been the driving force behind getting oil paints, watercolors, gouache, acrylics to have lightfastness standards. Standards create a level playing field and that brings out the best from all concerned. Companies that can’t conform stand out when a standard can be used as a yardstick to determine overall quality. In recent years, the colored pencil folks worked hard to craft a standard so that is why D6901 exists today. We have never had a group of organized pastel artist or organizations representing them put their full force behind an effort to create a pastel standard.

Sanford was not coping out. No requirement (or better put, a standard) exists for anyone to use for lightfastness testing. Someone mentioned that European manufacturers post lightfastness ratings on pastels they sell. That rating is based on the blue wool fading test that the raw pigment manufacturer conducts to give some rough indication as to the fastness of a colorant. This is nowhere near the robustness of any of the existing lightfast test methods used for art materials that have existing standards.

If the words “earth colors” in the red, yellow and orange families of hues were paired together, then yes, it would be correct that iron hydroxides are a common material found in these pigments. However, many hues in the yellow, red, orange range discussed do not rely on iron as the common element. Be happy that many do come from iron origins. They are the most stable lightfast materials in any media.

Nobody has the edge on lightfastness for pastels yet because no standard exists. You can argue that some manufacturers knowingly put fugitive materials in pastels but without them conducting a well -formulated testing protocol, they cannot know if the colors they use are lightfast. So for right now ignorance by the manufacturers is bliss. They don’t have to lie to you and say any of the colors they make are fugitive because they really don’t know for sure. However, preliminary testing conducted by ASTM indicates that many colors do have lightfastness issues. Some very predictable colors like violets and red-pink colors can be notorious for fading. But in looking at the bulk of the testing, colors fade across the entire hue family.

In summary, ASTM has provided the art materials world with quality standards for many forms of art material. These standards focus on the quality of the ingredients used, the proper labeling of materials, important health and safety labeling and lightfastness of the pigments. ASTM lightfastness tests are very stringent and if a material passes the test, it has good lightfastness qualities. The exposures are severe and enough duplication and redundancy is built into the test to assure that the results are valid.

We need volunteers to participate in testing. Artists and manufacturers meet together and work cooperatively to create test protocols, conduct the test to see that it works correctly and then publish the standards for industry to use. Help by artists is a critical component to the process. We really need pastel artists to attend meetings, become involved and in effect, push the manufacturers of pastels to adopt an ASTM lightfastness standard. Once a standard is developed and passed, manufacturers will want to follow it because a competitor will use the standard to proclaim that what they make is superior to that which is produced by other pastel manufacturers.

The ASTM subcommittee called D01.57 Artists’ Materials has around 60 members and another 20 interested parties who follow the work of the subcommittee. If you just want more information and wish to get involved visit the ASTM website to see what a standards making group actually does. If you want to know more about the work of the Artists’ Materials subcommittee D01.57, email me at dcl@nga.gov and I will answer your specific concerns. I am the current chairman of the subcommittee and am eager to make contact with those who wish to know more.

Michael Skalka
Chair, ASTM D01.57 Artists’Materials

Michael Skalka, Conservation Administrator
Subscribe to: The Grammar of Color- a paint history newsletter. Send an e-mail to: m-skalka@nga.gov with your name and a current e-mail address.

A question for the Pastel Societies

I know a number of leading members of pastel societies around the world read my blog.  So here's some questions just for you!
  1. Has your Pastel Society considered the question of lightfastness of soft pastels?
  2. If yes, why does your website not say more about the development of lightfastness standards and how members can become involved?  
  3. If no, why not? 
  4. What has your Society decided to do about promoting pastels which are accredited as lightfast?  
  5. Does your Pastel Society aim to benefit its members by having somebody leading on the development of fine art materials relevant to artists using pastels?
  6. Does your Pastel Society have any link at all with the ASTM and the development of the new lightfastness standard?


  1. I enjoyed reading your posts, but this one about lightfastness is especially critical. I would like to copy the info you discussed about pastel societies and what they could be doing. I belong to the Southeastern Pastel Society and would love to raise this issue with them to get going on. I will give credit to you and your blog for this information. Thanks! Marsha Hamby Savage

  2. That's absolutely fine Marsha - the more join in the better things will get!


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