As I began my run tonight, I spied, beneath stormy clouds, a rainbow. Red; orange; yellow; green; blue; indigo; violet - the usual suspects were all there. However, these sparse few hues are just a subset of the continuous spectrum of colours that make up visible light. On either side of that little band of light, there’s a whole range of colours that we cannot distinguish with the naked eye.
Rainbow over Newhaven, Edinburgh
This got me thinking back to a lecture hosted by Dutch astrophysicist Walter Lewin, dubbed “the hidden beauty of rainbows”. I’ll post a link to the recording below. Lewin is renowned for his contributions to physics education. A handful of the topics he explores include explanations of optical phenomena, electricity and magnetism, vibrations and waves, classical mechanics... He’s brilliant – witty, relatable – he brings a certain allure to the world of physics. I think… that the shadow cast by the sexual harassment allegations against him in 2014 tarnished his reputation and raised important questions about accountability in academia. Why he felt the need to victimise at least ten women I will never understand… I suppose ego and power derail even the greatest of minds. But despite this controversy, Lewin's contributions to physics education remain significant, inspiring countless students and enthusiasts alike.
"The Hidden Beauty of Rainbows" > sourceAs I ran, my mind wandered to occasions resembling the apparent "colour shifts" frequently noticed in varnishes on paintings. And I suppose this is what led me to write today’s article. My aim is to hopefully dispel the common misconception among those that attribute a painting’s colour change solely to degrading pigments...
The colour change I will write about tonight is often attributed to a phenomenon called "birefringence". Birefringence occurs when light passes through a material and is split into two rays, each traveling at a different speed. When these rays recombine, they can interfere with each other, resulting in changes in colour or intensity. In the case of varnishes, this phenomenon can cause the appearance of a yellow or brown tint over time.
”Comparison of positive and negative birefringence : In positive birefringence (figure 1), the ordinary ray (p-polarisation in this case w.r.t. magenta-coloured plane of incidence), perpendicular to optic axis A is the fast ray (F) while the extraordinary ray (s-polarisation in this case and parallel to optic axis A) is the slow ray (S). In negative birefringence (figure 2), it is the reverse.” > source
Now, comparing this to the angles of incidence in a rainbow involves understanding the optical properties of both phenomena. I’ll be honest - I've watched Lewin’s lecture over and over again and still can't wholly grasp the physics behind it. There was a time when I relied on my partner's exceptional gift for explaining complex concepts. He had a remarkable talent for unraveling intricate problems with such clarity, especially for someone like me, who is very much the novice... Physics isn’t my strong suit and requires a little more brainpower than the average “rabbit hole” I find myself plunging into, haha, but I’ll try my best to explain why it is I’ve decided to compare water to resin. (Stay with me – we’re getting there!)
A rainbow is formed by the dispersion, refraction, and reflection of light within water droplets in the atmosphere. So, light enters a water droplet and is refracted. It is then reflected by the back of the droplet. As this reflected light leaves the droplet, it is refracted again, at multiple angles. It is pretty phenomenal when you think about it. The colours of the rainbow are a result of different wavelengths of light being refracted at slightly different angles, creating the characteristic arc we see in moody skies, in light fogs, in the spray of sea at the tip of a stern, in waterfalls – yet it is an optical illusion, it does not exactly exist in a specific spot. A rainbow is the stuff of dreams.
Light prism, Sint Pauluskerk in Vaals
In both cases, the interaction of light with a medium (varnish or water droplets) is crucial. Just as the birefringence in varnishes can alter the colour of light passing through them, the refraction and dispersion of light in water droplets create the spectrum of colours in a rainbow. And when you remove that varnish… viola.
Of course, I’ve oversimplified the chemistry and physics a little bit – the mechanisms at play are different: birefringence primarily affects the polarisation and phase of light passing through a material, while the formation of a rainbow relies on the refraction and dispersion of light due to its passage through water droplets. But both phenomena involve the manipulation of light. And although the specific mechanisms and causes of colour change differ between varnish birefringence and the formation of rainbows, a similar idea persists... they are linked by illusion.
A varnish acts as a reversible form of protection for a painting, shielding it from dust, dirt, pollutants, impact, abrasion. Any filling and retouching of losses to the surface layers are applied between isolation layers of varnish, and these are also stripped from the painting’s surface during varnish removal – in case you were aghast at the amount of damage exposed in some of the images above. I think people forget that some paintings have lived several lives over. They accrue the wear and tear any living or inanimate thing accumulates over a lifetime...
The end goal is, obviously, to prolong the painting’s life – its colours and surface texture. A varnish, when first applied, saturates the colours of a painting in order to enhance the richness of an artist’s palette. It involves a meticulous understanding of resin chemistry, solvent selection, pH considerations, and application techniques.
Resins, whether natural or synthetic, form a film. The purpose of solvents is to dissolve the resin and facilitate application, proper drying, and adhesion. Additives, like cosmoloid (a wax) or tinuvin (a light stabiliser) modify the resin properties.
From wax infusions to adhesive pastes, the toolkit for working with the surface layers of a painting includes a variety of non-invasive examination methods such as ultraviolet light analysis and testing gels for varnish removal.
To sum it up, the purpose of varnish, much like a rainbow, is aesthetics. But, unlike a rainbow, resin has a physical lifespan that can last +/- 100y. And, as with anything in time, it degrades. It desaturates. It imbibes the dirt and dust and pollutants in the air around it. It oxidises, it destabilises. In essence, it dies. And then it is safely, ethically, farewelled, removed, and replaced.
And thus ends today’s musings. Apologies if I went on a bit - rather enthusiastic about light. There are more sensible ways to discuss things like varnish and rainbows, but... helaas. If you made it this far, well done, seriously.
Now, I release you.
Think about the beauty of birefringence.
Look out for angles of incidence.
Admire a painting.
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Blogger: @actaylor
Photographs: unless otherwise noted, all images were taken by me with an iPhone 8
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STOPTo support your work, I also upvoted your post!
Hey!
Never apologize for being passionate and enthusiastic about a subject, even if not many other people 'get it'...
That was indeed interesting... I'll admit that some of that (ok ok, a LOT of that) went over my head, but its still interesting regardless, and another reminder of how little I know about soooo many things.
Yep. My partner paints... it is a talent beyond my reach so I stick to photography instead!
Is that you doing the painting restoring stuff? Do you paint as well?
Hey @dannewton 💫 (My new strava buddy!!) Thanks for the comment - I admit, I can get a tad carried away with my excitement about [a lot of] stuff, hence the occasional preemptive apology... But I'm delighted you found this post interesting! (It is though, isn't it? Light is confounding!) Birefringence goes over my head, too - but what a great excuse to learn more?! I came across a great quote eons ago that I chant to myself every so often...
I think that quote is relevant here. You're right, of course! It's so good to be curious.
And how wonderful to learn that your partner is a painter! Thanks for sharing a link to her page - what beautiful paintings of wildlife - I especially like "Red Deer at Bradgate Park". 🌞 Although the turquoise in "Snipe at Framton Park" is stunning! I've given Dawn a follow. Does she plan on posting more regularly on Hive? I see her most recent posts are from two months ago!
Yes, that's me restoring stuff! 💃 And I do paint! But rarely... (I must confess, unlike Dawn I'm more of an oils fan myself, so I might be tipping the boat here - haha!) I used to take commissions - mainly portraits and the like. And I did feature works in some exhibits... I have an Etsy page for some prints of drawings... but I'm not nearly as invested in creating as I am in conserving creations! I really only create art for special occasions now. Although I have a mind to paint again. I did enjoy it.
lol no worries, feel free to 'geek out' as much as you wish... I'll be sat here trying to take it all in (and trying to keep up!)
'tis a lovely and poetic quote/phrase... I like this one which was apparently said by Einstein, although you can't trust some of these sites but regardless of who actually said it, I agree with the sentiment behind it... it is both humbling and inspiring in equal measure:
It IS good to be curious, and I think that mainstream society is starting to lose that, with everyone slumped on the sofa glued to netflix or scrolling through tiktok. We should be curious about our surroundings, and want to be inspired and explore... and I believe that the day we stop wanting to learn is the day we give up on living...
sorry for for the unnecessary negativity...lets change tack!
Dawn loves painting. She has done a few commissions, but honestly I think she felt constrained by the briefs, so these days she paints purely for fun/hobby purposes, and also as a way to relax. Her main focus is wildlife photography (and is currently at Carlisle Uni studying wildlife media), but tries to incorporate her art into what she is studying. She would'nt judge you for oils lol, she experiments with various media, but acrylics and ink are her preferences.
There is also an assortment of half finished pieces dotted around the house that I wish my partner would finish, but she keeps getting distracted and starting a new piece instead!
I'm sure Dawn'll appreciate the follow, although she doesn't really post here very frequently. Hive is awkward to use to be fair, and I've doggedly stuck around here for the past few years as I believe there is potential here when people push back against other social media platforms. But it does require work to build up a stake, and a following, and making connections... and Dawn is just not motivated enough to put the effort in. At my behest, she set up an account, and that is enough for now. I'm sure she'll post again in the Summer when she has more time.
Oh aee - that sentiment attributed to Einstein resonates deeply. Very similar to the quote I had... I wonder if it stems from the same source? Haha! Isn't it a beautiful reminder of endless wonder...
And your thoughts on curiosity are spot on @dannewton. In a world where Netflix binges and TikTok scrolling seem to dominate, nurturing interest becomes more important than ever... It might indeed be lacking presently - that desire to explore, to learn, and to truly live. As you rightly put it, the day we stop wanting to learn is the day we give up on living.
Shifting gears, it's wonderful to hear about Dawn's passion for painting and wildlife photography. I can relate to the struggle of balancing commissions with personal expression - it's a delicate balance, isn't it? And I suppose when "hobby" drifts into "work"... if you're no longer painting for pleasure and relaxation... it can become a gruelling task. And those half-finished pieces scattered around the house? You should tell Dawn that Leonardo Da Vinci made a habit of never fully finishing his works, haha. It must be a free spirit thing. Also, kudos to her curiosity! Perhaps her mind is just flitting from one interest to the next a little too quickly!
As for Hive... yeah, building a presence and making connections certainly takes effort. It's so nice to have met you though, Dan! And hey, no pressure for Dawn to post frequently - sometimes, a sporadic update can be just as meaningful. 🌞