Why is lightfastness important?

Before looking at the lightfastness of coloured pencils, let's first look at other media and discuss how they react with light.

The thinner the layer of colour on the surface, the more liable is the pigment to fade or change in bright sunlight. For this reason completed watercolours are carefully stored out of bright light and displayed with caution as the layer of paint on the paper is the most delicate and thinnest..

Oil paintings have some protection with the thick layers and the oils they are bound with. Even so, many "Old Masters" have reverted from bright colours to browns through years of being hung in galleries. Others have been lucky enough to be restored so still look fresh. In many cases the loss of colour is partly dirt and the failure of varnishes, but even the thickness of oil paint is not proof against fading.

Acrylics are similarly protected by the thickness of paint and the polymer binding along with the modern pigments using in manufacture.

Inks are usually based on more stable pigments and can be amongst the most permanent of the water based products.

The example above show the fading of colour that can happen from using non-lightfast pencils. This picture was photographed when it was completed, and then again after leaving it in strong Mediterranean sunlight for 6 months!

Lightfastness of coloured pencils

Pencil paintings react to light in much the same way as other art media and need as much care as watercolours.

Some pigments are more liable to fade. The older reds, purples, pinks and some blues tend to be less stable than the natural browns, yellows and greens.

With modern chemistry and the organic colours produced from the oil industry we now have a range of colours that are more stable in strong light.

For this reason many old stocks of pencils contain a higher proportion of unstable pigments and newly produced stock tends to have a higher lightfastness. Pencil manufacturers are now more conscious of the need for colours that will last.

Take care though. Most manufactures produce a wide range of pencil lines and not all will be made using the more expensive light resisting pigments. School and student lines will often be made with cheaper ingredients. Low price "own brand" coloured pencils sold by stores who do not specialise in art materials may well be more subject to fading.

Those manufacturers who produce lines specially made for artists and meet higher lightfastness requirements often have the highest priced products as they use more expensive pigments.

Manufactures also like to market a full range of colours, even if some of the pencils in the sets have low lightfastness. Not every buyer of coloured pencils is aware - or even interested - in whether the results of their work is liable to fade.

Speaking to the manufactures, the common factor is that they make the highest profit on the lower cost student and school products. The highest quality are materials made for discerning artists are often those sold with the smallest margin. They are manufactured and sold to gain the quality name that sells their other stock.

Why do watercolour and wax pencils carry different ratings?

A pigment used in a wax-based (non-soluble) pencil will usually have a higher lightfastness rating than the same pigment in an Aquarelle or watercolour pencil.

In the water soluble pencils the eventual thickness of pigment once it is brushed in with water will be less than when it is simply laid on the surface with a wax binder. The pigment is usually the same, it is just that the thinner layer of colour in the aquarelle is more delicate and likely to fade.

In July 2013 Caran d'Ache introduced a new watercolour pencil line into the UK. Museum Aquarelles are soft, strongly pigmented and also lightfast. They have been sampled and tested, with the results included on the Caran d'Ache web site. The pencils have a high standard of lightfastness both dry and wet. Therefore, they have very good durability with ratings of 3 stars and above on the Blue Wool Scale.

Are there colours to avoid?

Because the amount of pigment in pale colours is lower than the quantity in stronger shades (due to the mixing of more filler with the pigments), paler colours - particularly blues and pinks, tend to have the lowest protection against fading.

Many older brands of pencil have lower ratings. but some newly formulated pencils can have low light ratings too.

If you want your artwork to last, you need to check the standard of the colours you use. Refer to the manufacturers websites and literature. You will usually find some references to the lightfastness (UV rating) where you can find the colours listed.

Blue Wool Scale rating

If a ‘Blue Wool Scale’ rating is shown, the highest rating is 8 - the most lightfast - and anything of 6 and above is considered acceptably lightfast. Personally I try to avoid colours rated 4 and below and consider 5 as just about acceptable.

Star rating

Some pencils carry a star rating and I try to avoid any with a 1 star mark and only use the 2 and 3 star pencils.

Try to check out the rating either from the pencils ( Faber Castell and Caran d’Ache) or from the manufacturers website (Derwent). If you can’t get hold of a rating, treat pinks, purples and reds with caution - especially the pale colours which, as noted above, very often have low pigment levels. Strong light can encourage the little pigment that is there to fade.

ASTMS 6901

Some brands conform to ASTMS 6901 and carry reference to LF1 and LF2 gradings.

This is tested on the actual pencils and as such is the highest test rating. LF 1 and 2 are excellent - one is higher than 2, though! See further down the page for more information on ASTMS 6901.

ASTMS 4303

One or two brands show testing to ASTMS 4303. This is testing on the actual colourants used in the pencils and whilst it is not a test of the pencils, it is a good indication that the colours you lay down will last

You don't want to spend many hours on your artwork only to see it all lost as the colour disappears.

Manufacturers lightfastness settings

This site used to have links to manufacturer’s websites quoting lightfastness levels. But since 2011 we have found that many of those links have changed, so it has proved impossible to keep up with publishing them. CHECK with a Google search as most pencil brands are listed on the internet with Lightfastness levels.

The guide below will give you a place to start.

DERWENT (use the Blue Wool Scale) - try to avoid 1 and 2 star pencils

FABER CASTELL (use their own star system) - try to avoid 1 star pencils

CARAN D'ACHE (also use a star system for brands other than Luminance and Museum) - Avoid 1 and 2 star pencils

Luminance ratings are given as LF1 and LF2 - according to the ASTMS 6901 data, LF1 is 100% lightfast and LF2 is 80% lightfast. All Luminance colours can be considered fine for coloured pencil work.

PRISMACOLOR - Sanford have been very coy in the past about publishing the data.

However they have now published an official Prismacolor Premier Chart showing the colour card and the official ASTMS 6901 ratings for their main 132 colours (and blender).

They show the range with the 5 grades listed from excellent ( 1 ) to poor ( 5 )

On this scale, the serious coloured pencil artist would normally be aiming to use those in grades 1 and 2 and there are 72 colours Prismacolor Premier pencils that match this aim, with quite a few of the ‘good’ colours, shades of grey or white.

DERWENT LIGHTFAST - All the colours comply with ASTMS 6901. The pencils are OIL based ( a new departure for Derwent who usually base their ranges on wax or mainly wax and some oil ). Softer than Faber Castell Polychromos. An expensive pencil, on a par with Luminance for cost.

OTHER BRANDS

Staedtler and Lyra do not publish data on the internet - or if they do, I haven’t found it in any leaflets. UV star ratings for Lyra are shown against each colour inside the lid of the box.

TALENS ( VAN GOGH ) - Talens say that the Van Gogh range ‘meet the standards of ASTMS 6901’

I also understand the Dutch made Bruynzeel FullColor pencils are lightfast, but I have no data and they are not available in the UK

CRETACOLOUR - Made in Austria by the successors to the Hardmuth pencil business.

Colours of the 36 Karmina (dry point) and Marino (watercolour) pencils meet the ASTMS 4303 standard with all colours either LF1 or LF2.

Karmina can be very difficult to find, but Marino are on sale in the UK and I have tested them as very good (and not highly priced).

ASTMS ratings for lightfastness

The notes here are based on the American Standard Testing paperwork.

ASTMS 6901 relates specifically to coloured pencils and is product based i.e testing is done on the actual pencils and the artwork done with them.

ASTMS 4303 relates to lightfastness of pigments and artists colours in general and relates to the ingredients.

ASTMS 4303 Testing is not done on the product, it is done on the ingredients.

From reading that article it should be clear that this kind of reporting results is not predictive- ASTM D01.57 does not predict the "service life" of materials.

In conclusion

If you wish to preserve the quality of the colour in a coloured pencil picture, you can take further steps to protect the image.

You can spray the finished work with a fixative that also adds a protective Ultra Violet light filter and will therefore add a layer of protection.
You can also have the picture mounted and framed up behind a special protective glass or plastic which will also provide more UV protection.

Both these protections will add a filter between the picture surface and the viewer, so some colour will be affected