Lightfastness tests

As an artist who sells original work I've always been concerned about lightfastness and overall durability. 

What's lightfastness? A property that describes how resistant to fading a pigment is when exposed to light. A, resistant pigment is called lightfast; a pigment that fades or colour shifts is called fugitive. 

When I started out I trusted the lightfastness rating each watercolour company gave on paint labels. Little by little I began developing trust issues. 

You may ask why.

It all began when the Daniel Smith Mayan Blue Genuine I poured on my palette colour shifted and became blackish a year after being poured on the palette. 

The palette was kept closed in a dry area, no mold, no sun exposure. 

When I noticed the hue change I assumed it was my fault for letting it get in, contact with oxygen, thus producing oxydation. So I decided to only use this colour straight from the tube. 

It turned out I was trusting Daniel Smith's label. 

Researching about lightfastness 

I began doing some research on this topic and found many interesting YouTube videos and blog entries from fellow watercolour artists that had had problems with mislabeled paints and were conducting their own lightfastness tests. 

To my surprise, I discovered Daniel Smith often mislabeled fugitive paints as lightfast. 

One of their most popular special granulating colours, Moonglow, is fugitive!! It contains the red pigment PR177 which Daniel Smith rates as "NR" LI (excellent lightfastness). The pigment fades in just 2-3 months of direct sun exposure. 

So I decided to do my own lightfastness tests as many other artists have. 

The Lightfastness tests

I painted the swatches and put them on top of my roof to receive extreme sun exposure during summer months. The swatches were put outdoors the 25th June 2021.

How do the swatches work? For every colour tested there are two stripes of paint: a masstone swatch (undiluted paint at full strength) and a diluted swatch. 

In the image above you can see a comparison between Moonglow exposed to sun for 2 months (top) and Moonglow kept inside a drawer (bottom). As you can see in the diluted swatch, all the red PR177 has faded and only the blue and green are left. 

If you're curious about the colours I'm testing and the updates before I upload the scanned results after 6 months, you can check out my YouTube videos:

I've selected a few colours from different brands to see if the lightfastness rating is accurate or not. 

These are the brands being tested:

Kuretake Gansai Tambi

Beam Paints 

Schmincke 

Lukas

CSY Art Gallery handmade watercolors 

White Nights 

Winsor & Newton professional 

My own handmade watercolors 

Paul Rubens 

Daniel Smith

Roman Szmal

Rosa Gallery

Sennelier

Once the swatches have been receiving sun light for 6 months, I'll do a complete blog entry with comparison scans and pigment information.