top of page

LuxeSci Show Notes: S2E3 - Black and Blue and Pigments Too

Hello again.  Welcome back to LuxeSci, a podcast to re-ignite your wonder by exploring the science of luxury.  

Before we start today, I have a very excited announcement.  We’ve just launched our new website and science communication endeavor.  The website is  

Erevna Media is website where we will host all things LuxeSci (episodes, show notes, etc) and where Dr. Dimos and I will both have blogs and we will share science that we think is fun and interesting.  

So please visit the website and subscribe so you don’t miss any of the nerdy fun.

After a brief departure for our 1st Anniversary, we’re back into talking about visual art.  In Episode 1, we talked about how we, as humans, see color.  Today, we’re going to explore how colors are created, specifically for paints.

 I’ve also recently read two books that I highly recommend, The Secret Lives of Color by Kassia St. Clair (which was recommended by the amazing designer who did our new website) and Color: A Natural History of the Palette by Victoria Finlay.  Both of these books are incredibly interesting and entertaining journeys into pigments and color.

So where to begin.  Given that there are at least two books (and I’m sure countless more) about pigments and color and painting, we could do a whole season (or more) on color but that’s not really our style.  Our style is to provide just enough cool facts to whet your appetite and get you interested in learning more, perhaps pulling up some Google to do so.

HistorySo let’s start at the beginning, at least as far as we know.

  • Almost since the beginning of humanity, people have been drawing and using pigments to depict scenes of life and religious scenes

  • However, this may not be the oldest art

  • Red markings in a cave in South Africa were created 73,000 years ago

  • Cave paintings in Spain are thought to be 64,000 years old

  • For reference - the caves of El Castillo in Spain and the Chauvet cave in France are dated between 35,000 to 40,000 years ago and Lascaux in France dates back to 17000 years ago

  • So what pigments would these early artists use?

  • Early pigments were materials that could be found in nature.  The dominant ones are red (iron oxide, natural hematite or heated goethite) and black (charcoal or manganese oxide)

  • Ochre is also a huge pigment in both ancient and more modern art

  • Ochre - natural clay earth pigment 

  • Mixture of ferric oxide and clay and sand

  • Colors range from yellow to deep orange or brown and can also be red went it contains dehydrated iron oxide


  • So this brings us to how paints actually work, scientifically…

  • Pigment powders need some sort of binder and the type of paint dictates that type of binder

  • I think the best pigment/binder combination to illustrate what’s going on at a molecular level is oil paint

  • The binders are all polymers, which is a fancy way of saying something is made up of large molecules (poly = many).  These large molecules get a little tangled up when they are in a solution and this tangling adds strength to the paint.  (think of the difference in the viscosity between a solution of completely dissolved salt in water and a thick oil, such as motor oil).  

  • The pigment particles will get suspended in the binder (and not dissolved the way a salt will in water)

  • This suspension allows the artist to add different pigments to change the color

  • The binder also allow the pigment particles to stick together and to stick to whatever surface is being painted.  It essentially forms a matrix to hold the pigment in place

  • Interesting side note - for oil paints, pigment is added to a “drying oil”, with linseed being the most common.  As the linseed oil absorbs oxygen, just by hanging around, it will be converted from a liquid to a hard, permanent coating.

  • So oil paints do dry - just very slowly sometimes

  • This is a version of a thermoplastic mechanism - how a film forms (think something like wax, which is liquid when warm and hard when cool)

  • For oil paints - first the solvents evaporate by reaction with oxygen and then a crosslinked network/film is developed and this gives that hard, permanent coating.

  • An extender can also be added - these are large pigment particles that will improve the adhesion of the paint and strengthen it without using more binder

  • Lastly, there is usually a solvent added to the paint.  Just the pigment and binder produces a paste that can be hard to work with.  The most common solvent is water though other chemicals can be used. 

  • Additional chemicals can be added depending on what type of paint it is, for example, adding fluorescent pigments for fluorescent paint.

  • So to summarize, paint is made of:

  • Pigment - color

  • Binder - glue

  • Extenders - help adhesion

  • Solvents - to make it spreadable

  • We could go on and on about the chemistry behind paint manufacturing and there are whole industries dedicated to it, 

  • but we’re here to talk about the color!  So to start us off, is Dimos to talk about two sort-of non-colors.


  • Blue is widely reported as a favorite color and it’s easy to see why.  It’s the color of the sky and the ocean and stirs up feelings of calm and serenity.  But blue pigment has long been a struggle for artists, mostly because natural glue pigments are rare.

  • While the history of blue dyes is a long and fascinating one, we don’t have hours and hours to discuss so I’m going to highlight some of the dyes that I found particularly interesting.

  • Egyptian Blue

  • Let’s take a little trip back to when you were first learning about ancient Egypt.  What struck you about the paintings and hieroglyphics?  Was it the content?  Or are you like me and what struck you was the colors.  They were so vibrant, even so many years later.  What is also unusual is the range of colors, specifically blue.  

  • Up until the Egyptians, blue pigment was extremely rare, with its only source being Lapis lazuli (which we’ll discuss in a minute).

  • Blue was so important to the Ancient Egyptians that they invented a way to manufacture the pigment.

  • You would take a bit of sand (siica), copper from minerals like azurite or malachite, natron (mixture of sodium compounds) and heat these to 800-900C.

  • You’d want to make sure that there are lime impurities in your sand or this won’t work.

  • And this was all taking place around 2200 BC (around the time of the Great Pyramids)

  • The result would be Cuprorivaite, carbon dioxide and water vaspor, or an opaque blue glass that could be crushed up, mixed with egg whites (binder!) or gums and made into pain that clearly stood the test of time.

  • Regular blue crystals with unreacted quartz and some glass

  • Interestingly, the Egyptain blue specimens tested thus far contain excess silica and CuO or CaO, which would have made the pigment harder in texture.  This is believed to have been intentional by the pigment makers

  • This blue was so popular that it stormed the market and was prevalent throughout the Roman Empire - in fact, the recipe that we have for Egyptian Blue is from a Roman.

  • In 2006 - Giovanni Verri, a conservation scientist was looking at a Greek marble basin under fluorescent lights and was a bit surprised when the blue pigments in the vessel were glowing.  This was the first indication that Egyptian blue emits infrared radiation.  This property of the pigment allows scientists to get a better idea of what ancient artifacts looked like and provided the first clues that items, such as the Elgin marbles (pieces of the Parthenon stolen by the UK) were in fact painted and not the monochromatic white that they are today.

  • This may have other benefits since infrared radiation has greater penetration into human tissues and the luminescence of Egyptian blue is so lasting, it could be used as an imaging die for biomedical images.

  • Ultramarine

  • Let’s go back to ancient Egypt, where beautiful chunks of lapis lazuli have been imported from Afghanistan and used for jewelry and headdresses.  Now imagine you think to yourself, I could grind this up and make a beautiful blue dye that would be both easier than making Egyptian Blue and have the added cache of being ground up semiprecious stones.  

  • So you take your mortal and pestle and you get to grinding, only to find that lapis lazuli is not one stone, but  a stone with many minerals embedded in it, such as calcite, pyrite, mica, etc.  And while those minerals make the intricate veins that are sort after in the stone, they lead to a dull gray powder when ground.

  • Cave paintings in Afghanastan for Zorastrian and Buddhist temples fromthe 6th and 7th centuries contain the first noted use of lapis lazuli as a pigment, likely because since the caves were close to the mine, they could get pure samples to grind into the blue powder

  • The blue cubic mineral, lazurite is what you want for a pigment and it is a sulfur-containing sodium-silicate, which makes ultramarine the most complex of all mineral pigments

  • So let’s fast forward a bit to the 13th century, the Silk Road means that lapis lazuli is again a hot commodity and color mixers are keen to bena be able to turn more of the stone into pigment.  A process was invented extract the lazurite from the rest of the stone and this was used extensively throughout the 14th and 15th centuries, (think Titian, Michelangelo, Rafael, etc)

  • The presence of the sulfur as a double-edged sword though since it makes the paint sensitive to mineral acids and acid vapors, which turn it into hydrogen sulfide and it is also very sensitive to being outdoors

  • Prussian Blue

  • Eventually the cost of ultramarine prompted chemists to try to invite a synthetic blue and there were several that were used by artists.  One interesting one is Prussian Blue

  • Prussian Blue is one of those happy scientific accidents that occur when a scientist is trying to do something else

  • Picture a paint maker in the early 1700s in his shop, mixing away, trying to make red pigment from cochineal (dried bug husks).  You spill a little animal blood into your potassium sample (or maybe you have to kill a rat and it gets into it) and you think, hey, no big deal, blood is red.

  • But instead of red, the dye that results is a very deep blue.

  • Prussian blue is blue because the iron in the compound is in two different valency states and this allows the electrons to move from one orbit to another = strong absorption in the orange/red part of the electromagnetic wavelengths = strong reddish blue color to our eyes

  • It is unstable in an alkali situation so it can’t be used in most aqueous media

  • Today the color is used in printing inks but also as a powerful antidote to heavy-metal poisoning and by scientists such as myself to stain cells to look for internal structure or for identification

  • New blue color

  • Now i know i’ve rambled on about blues for a while now but i have one more…

  • In 2009, researchers at Oregon State University discovered a new blue pigment, which was the first in 200 years

  • It was approved for commercial use by the EPA in 2020

  • Its called YlnMn, after it’s chemical components, yttrium, indium and manganese oxide.

  • It’s a very bright blue color

  • This discovery too happened by happy accident. Dr. Subramanian and his grad student, Andrew Smith were looking into novel materials for electronics.  They looked a oxide solid solution using YInO3 and YMno3 at 1093C and what they found was a bright blue pigment

  • It’s stable, doesn’t fade and is non-toxic (unlike cobalt blue) and can be used in oil and water


  • Pigment - small particles of color

  • Binder - substance made up of larger molecules that binds the pigment

  • Solvent - solution to help the paint spread better

  • Oxide solution - ask Dimos

Fun Party Facts

  • How old are the oldest known cave drawings - ~70,000 years old

  • Who were the first people to make a processed blue dye - the Egyptians

  • What were the creators of the newest blue dye trying to do - make novel materials for electronics

Thank you again for listening to this season premiere of LuxeSci.  As always, many thanks to my cohost and audio engineer, Dimos.  OUr theme music is Harlequin Mood by Birdie.

You can follow all over social media at LuxeScipod.  Definitely give our Youtube channel a follow since we’ve been posting weekly cocktails and science discussions (Science Sips), some videos from around Greece and our LuxeSci Field trips

Your assignment for the next two weeks: leave us a review on Spotify, Apple Podcast, Youtube or wherever you listen to your podcasts.


bottom of page