13 ms·

Paint Is Colored Glue

273 points by pshaw 8y ago

deleted 8y ago
[deleted]
nakedrobot2 8y ago
No it's not, as the author says in the 3rd sentence of the article. Watercolor paint is not an adhesive in any sense of the word. And there are plenty of paints which also dry, leaving a powder behind that can easily rub off. So yeah, some paint is glue, some is not.
- fit2rule 8y ago
  I think its fair to say you might've missed the opportunity to grant some poetic license. Maybe the wider point was the more philosophical one: art binds our minds together, and therefore paintings are a kind of mind glue, figuratively ..
- lqet 8y ago
  At least the abstract is more precise: > The secret of oil paint, as mastered by our greatest artists Nevertheless, an interesting read.
  - mrob 8y ago
    The 4th sentence is about watercolor paint: >Watercolor paint does it by drying, releasing water into the air through evaporation and leaving only the pigments on the page. This is not glue.
    - stan_rogers 8y ago
      The binder, gum arabic, is. There's just not much of it.
lqet 8y ago
I remember being quite blown away as a 20 year old during a trip to Paris by some of the paintings in the Louvre and the Musée d'Orsay. I had known many of these paintings before, from Wikipedia and school books, but it seems to be impossible to capture the effect of an oil painting in a digital or reproduced image, because, as the article describes, an oil painting is essentially 3-dimensional. (I also distinctly remember being shocked by the size of some paintings, especially the crowning of Napoleon (https://en.wikipedia.org/wiki/Coronation_of_Napoleon_I#/media/File:Jacques-Louis_David_-_The_Coronation_of_Napoleon_(1805-1807).jpg https://en.wikipedia.org/wiki/Coronation_of_Napoleon_I#/medi...) This painting was printed in many of my history school books, but I was not even remotely aware that is nearly 10 meters wide.)
- bufferoverflow 8y ago
  It's not impossible, computers have been modeling 3D fluids for a long time. It might be computationally intensive, but definitely not impossible.
  - simias 8y ago
    He's talking about reproduction, not modeling. You can model the painting's physics all you want, you still won't be able to make a faithful reproduction on a flat and gamut-limited LCD screen.
    - mrob 8y ago
      With head tracking it should be possible to get close. The thickness changes are small, so the 3D effect is mostly from the uneven light reflection revealed by head movement, not stereopsis.
      - jdietrich 8y ago
        The texture of oil on canvas is extraordinarily complex and subtle. You would need billions of pixels and polygons and trillions of rays to even begin to capture the heavy impasto of Van Gogh or the coarse diffusion of Bacon.
k__ 8y ago
That's why you can "glue" wallpaper on the wall with paint. Rather helpful knowledge, when you just want to put a small piece over a blemish on the wall.
kowdermeister 8y ago
Is there a hidden analogy to programming that I missed? :)
- inopinatus 8y ago
  Yes. http://www.paulgraham.com/hp.html http://www.paulgraham.com/hp.html
  - kowdermeister 8y ago
    Thanks for the link instead of a downvote, never seen this post.
    - dictum 8y ago
      I didn't downvote, but your comment comes across as dismissive of the subject because it isn't directly related to digital tech.
      - stevehawk 8y ago
        To clarify, the smiley makes condescending.
        kowdermeister 8y ago
        Really? It was not the intention. I just found it odd to be on the top of HN, so I assumed it to have a deeper meaning which I still find funny.
        stevehawk 7y ago
        I know, it's the burden of text.
      - kowdermeister 8y ago
        Ignorant at best ;) It's nice to let to learn about other viewpoints though.
IshKebab 8y ago
Interesting. I wish they hadn't thrown in this nonsense though: > It's exactly the intricate expressiveness of oil paint that made Renaissance art so sensual and passionate
jrochkind1 8y ago
> Linseed oil is also used for many applications beyond oil paint, such as treating wood, to create a transparent, protective plastic barrier -- just as oil paint does, but this time, without color. Or for seasoning cast iron! https://www.cooksillustrated.com/how_tos/5820-the-ultimate-way-to-season-cast-iron https://www.cooksillustrated.com/how_tos/5820-the-ultimate-w...
- skj 8y ago
  Before anyone runs with your suggestion, it's worth pointing out that flaxseed is what people can use (which is a food-grade equivalent to linseed). And then before anyone runs with that suggestion, it's actually not a great way to season cast iron - it turns brittle and the seasoning will chip away (experienced this myself, and then did research). A great place to start for seasoning cast iron is on reddit: https://www.reddit.com/r/castiron/comments/5rhq9n/the_rcastiron_faq_start_here/ https://www.reddit.com/r/castiron/comments/5rhq9n/the_rcasti...
  - jrochkind1 8y ago
    The flaxseed oil method has worked great for me so far. But it is indeed a great internet debate. :)
pmoriarty 8y ago
Dough is edible glue.
- twic 8y ago
  All glue is dough if you're brave enough.
- kaybe 8y ago
  For better glue I recommend gummy bears as raw material. Starch-based ones are more brittle. (Disclaimer: I am probably not the best gluemaker.)
H1Supreme 8y ago
The technique described as "They overlaid many thin layers of oil paint" is technically called glazing. And, by "thin" layers, they mean a layer that is mostly oil, with varying levels of pigment. Many of the old masters would paint a detailed, monochromatic underpainting, and glaze many layers of color on top of it. Definitely not a process used by people who want to finish quickly.
- gknoy 8y ago
  That's interesting, it's very similar to the way many comics are done -- one person does the drawing and inking, and it's often colored by a different person (or at least as a different process if the team is small).
mwexler 8y ago
This extract is from Delancey Place, which sends a daily email with a para or two from a fascinating book. I am rarely disappointed with their choices. Affilitate link to buy book is at bottom of email, but they seem to invest far more heart in this effort than the revenue would support. Sometimes, curated discovery is just what you need in a rushed morning. Very recommended.
mauvehaus 8y ago
Paint, as understood by oil painters and artists, sounds like a slightly different animal than paint as understood by house painters, wood finishers, and other sorts of people with more prosaic requirements of their paints. Bob Flexner wrote a book for wood finishers, Understanding Wood Finishing, that breaks down oil paint in simple terms for the rest of us: Some oils (like linseed and walnut) are drying oils, and can be used as a finish on their own, but don't really form a hard film finish. For that you need a varnish, which is an oil cooked with a resin. Paint is a varnish with a pigment added. That's different from an oil mixed with a pigment mentioned in the article, which is probably fundamentally similar to a straight oil in terms of its properties. Maybe somebody who paints with oil paints can weigh in? His columns in Popular Woodworking and other woodworking magazines are worth a read, as is his book, if you're interested in understanding what you're really working with. Tying this all back to the article, I'd disagree with the claim that paint is "colored glue". One typically doesn't glue things together with paint, though that is a sometimes unintended consequence of putting something on top of something else with an incompletely cured layer of finish. You certainly couldn't use e.g. linseed oil as a glue in a joint where oxygen isn't getting in readily like a mortise and tenon joint. A discussion of oil vs varnish here: https://www.popularwoodworking.com/techniques/finishing/oil-finishes-their-history-and-use/ https://www.popularwoodworking.com/techniques/finishing/oil-...
- abakker 8y ago
  Not a direct response, but in the case of modern automotive paints, especially 2 part urethane or epoxy ones it is exactly right - they're even based on the same chemicals! Of course, that doesn't really mean that paints work as glues, but you can add pigment/dye to a lot of glues and get a workable paint. (workable in the sense that they will adhere and color. they may not have the consistency that makes them work well as a paint).
- frontloadpro 8y ago
  The Chem Engineer finds terms like Resin, useless. It's kind of like saying, tape. Which tape? Easy peel? Or duct tape? I imagine that this is possible because there is only one type of resin that's useful in this field. Or trade secrets...
hjk05 8y ago
Cars are Red. (Not true in general but true for a subset, which does not make it true in general) So no, cars aren’t red and pains isn’t glue.
qubex 8y ago
I run a paint production company here in Italy (decorative for interior/exterior house use, and various kinds of high-grade industrial coatings) so this article (not to mention the fact that it somehow climbed it was to the top of the front page) amuses me no end. I've forwarded it to all of my colleagues and they'll all in stitches too. Because basically deep down we know this is the most succinct and relatable description of what we do with our lives. Try as we might to aggrandise things, this is the truth stripped bare. Unvarnished truth, even. ;)
- amarte 8y ago
  This article is really interesting and I love the insight provided about pigment layering to achieve remarkable effects, however I think what the title says is totally wrong. Paints are technically coatings and comprise a large and diverse industry of products for wide-ranging applications. Wall paint is very different than artist paint, which is very different than car paint, which is very different than the type of paint you might apply to pipes to prevent corrosion, etc.. Glue is an adhesive, and while the resins used to make adhesives may sometimes be the same resins used to make coatings (Gorilla glue is epoxy-based, and many floor coatings you walk over all day and never think about are epoxy-based as well), the actual products being used -- the can of paint or the stick of glue you buy at the store -- are formulated with resins, pigments, additives, binders, chain-extenders, fillers etc etc, that are specific to the product's unique application. So basically, paint is not glue. Paints are coatings and glues are adhesives. Sure, paints have to adhere to their substrates, and adhesives must adhere to their sometimes very different substrates as well, but paint and glue are really totally different things. You could say that coatings and adhesives are both formulated polymeric systems, but you miss out on a lot of interesting subtlety that entire industries are based on when you say "paint is glue."
mxfh 8y ago
"The effect of layering is so powerful that it has transcended its roots in painting with oils and is now incorporated into all professional digital illustration tools. If you use Photoshop, or Illustrator, or any other computer graphics tools, you'll be making images in layers." The layering described there, is more about what blend modes are for, layering can also be quite dumb by itself. The roots of DTP software layers lie pretty much all in the necessities of print, not painting, where you have to have a layer per color anyway. Wondering why the article stops short of the point, why (digital) reproduction of paintings is a lossy process in general, and especially for archiving. Total Appearance Capture systems exist but are rarely applied to paintings. A 2D-RGB raster can only represent the appearance of a light reflective object from a single angle und very specific ambient conditions. How a painting interacts with light in a room is a complex process of all kinds of optical phenomena (reflection, absorbtion, diffraction, refraction ...) as described in the arcticle.
Syzygies 8y ago
Labor has become more expensive than parts, for many aspects of home repair. We haven't adapted our habits to this. The last time I let my university landlord paint my apartment, it took days to clear the furniture, and I was instructed to do no paint prep. There were peels coming down from the ceiling. The painters exploited this "paint is glue" theory by painting under the peels and pushing them flat. I channeled my desire to kill them on the spot by politely escorted them out in mid-job and never letting anyone paint for me again. The next time I painted this apartment, I stripped the ceiling bare of its many poorly applied layers, and applied $500 of artist-grade acrylic primer and titanium white paint to the ceiling and walls. 15 years later, the apartment looks just-painted. Artist-grade acrylic paint is one of the best glues available, much more reliably so than oil paint. In the years since, the best wall paints have come closer to artist-grade acrylic paints, and their glues are likely better tuned to typical conditions. Artist paint is more expensive and better. Carefully tuning a cheap glue is like botching an airplane hardware design and trying to fix it in software. Later in a home, filling holes in contractor botched cabinet work, I started with artist-grade acrylic modeling putty, added just enough dye from the commercial paint manufacturer to match the existing cabinet paint, tweaked the gloss to also match, and created a one-step wood fill that disappeared into the existing paint job when dry. Much less shrinkage than commercial wood fills, and no primer or repainting needed. Again, acrylic art supplies making the best glue.
- drawkcab 8y ago
  Did you apply any mud to smooth the surface before you painted the apartment?
  - Syzygies 8y ago
    As needed, but once I got to bare concrete/whatever it was remarkably smooth. I chipped off the ceiling slowly over weeks, avoiding gouging.
    - HillaryBriss 8y ago
      what about lead? how did you handle the old lead paint layers?
deleted 8y ago
[deleted]
shutDeeFuckUp 8y ago
Eat my fuck.
Daub 8y ago
One point the article missed is the relationship between Canvas, primer, medium and oil paint. All three are traditionally derived from the same plant: flax. For this reason, there is great chemical compatibility between them, which accounts for their longevity. Even longer lasting is Buon fresco (the earliest form of fresco). This is essentially pigment painted into wet plaster. The paint is not a glue, rather a stain. Effectively the support and the paint are one. Another interesting point is the difference between how light paint is applied to dark. Light paint is usually painted quite thickly, and for this reason is very good at reflecting light. This improves the upper registers of the painting. The last thing you want dark paint to do is reflect light. Thickly applied black paint takes on a very 'flat' look. An experienced oil painter would apply black paint as a very thin and 'dry' layer (dry = no or little medium). They are also likely to employ an underpainting layer of brown-red. Applied in this manner the darks have a profound depth. The end result is a profoundly wide dynamic range.

273 points by pshaw 8y ago

deleted 8y ago

[deleted]

No it's not, as the author says in the 3rd sentence of the article. Watercolor paint is not an adhesive in any sense of the word. And there are plenty of paints which also dry, leaving a powder behind that can easily rub off. So yeah, some paint is glue, some is not.

fit2rule 8y ago
I think its fair to say you might've missed the opportunity to grant some poetic license. Maybe the wider point was the more philosophical one: art binds our minds together, and therefore paintings are a kind of mind glue, figuratively ..
lqet 8y ago
At least the abstract is more precise: > The secret of oil paint, as mastered by our greatest artists Nevertheless, an interesting read.
- mrob 8y ago
  The 4th sentence is about watercolor paint: >Watercolor paint does it by drying, releasing water into the air through evaporation and leaving only the pigments on the page. This is not glue.
  - stan_rogers 8y ago
    The binder, gum arabic, is. There's just not much of it.

lqet 8y ago

I remember being quite blown away as a 20 year old during a trip to Paris by some of the paintings in the Louvre and the Musée d'Orsay. I had known many of these paintings before, from Wikipedia and school books, but it seems to be impossible to capture the effect of an oil painting in a digital or reproduced image, because, as the article describes, an oil painting is essentially 3-dimensional. (I also distinctly remember being shocked by the size of some paintings, especially the crowning of Napoleon (https://en.wikipedia.org/wiki/Coronation_of_Napoleon_I#/media/File:Jacques-Louis_David_-_The_Coronation_of_Napoleon_(1805-1807).jpg https://en.wikipedia.org/wiki/Coronation_of_Napoleon_I#/medi...) This painting was printed in many of my history school books, but I was not even remotely aware that is nearly 10 meters wide.)

bufferoverflow 8y ago
It's not impossible, computers have been modeling 3D fluids for a long time. It might be computationally intensive, but definitely not impossible.
- simias 8y ago
  He's talking about reproduction, not modeling. You can model the painting's physics all you want, you still won't be able to make a faithful reproduction on a flat and gamut-limited LCD screen.
  - mrob 8y ago
    With head tracking it should be possible to get close. The thickness changes are small, so the 3D effect is mostly from the uneven light reflection revealed by head movement, not stereopsis.
    - jdietrich 8y ago
      The texture of oil on canvas is extraordinarily complex and subtle. You would need billions of pixels and polygons and trillions of rays to even begin to capture the heavy impasto of Van Gogh or the coarse diffusion of Bacon.

k__ 8y ago

That's why you can "glue" wallpaper on the wall with paint. Rather helpful knowledge, when you just want to put a small piece over a blemish on the wall.

kowdermeister 8y ago

Is there a hidden analogy to programming that I missed? :)

inopinatus 8y ago
Yes. http://www.paulgraham.com/hp.html http://www.paulgraham.com/hp.html
- kowdermeister 8y ago
  Thanks for the link instead of a downvote, never seen this post.
  - dictum 8y ago
    I didn't downvote, but your comment comes across as dismissive of the subject because it isn't directly related to digital tech.
    - stevehawk 8y ago
      To clarify, the smiley makes condescending.
      - kowdermeister 8y ago
        Really? It was not the intention. I just found it odd to be on the top of HN, so I assumed it to have a deeper meaning which I still find funny.
        stevehawk 7y ago
        I know, it's the burden of text.
    - kowdermeister 8y ago
      Ignorant at best ;) It's nice to let to learn about other viewpoints though.

IshKebab 8y ago

Interesting. I wish they hadn't thrown in this nonsense though: > It's exactly the intricate expressiveness of oil paint that made Renaissance art so sensual and passionate

jrochkind1 8y ago

> Linseed oil is also used for many applications beyond oil paint, such as treating wood, to create a transparent, protective plastic barrier -- just as oil paint does, but this time, without color. Or for seasoning cast iron! https://www.cooksillustrated.com/how_tos/5820-the-ultimate-way-to-season-cast-iron https://www.cooksillustrated.com/how_tos/5820-the-ultimate-w...

skj 8y ago
Before anyone runs with your suggestion, it's worth pointing out that flaxseed is what people can use (which is a food-grade equivalent to linseed). And then before anyone runs with that suggestion, it's actually not a great way to season cast iron - it turns brittle and the seasoning will chip away (experienced this myself, and then did research). A great place to start for seasoning cast iron is on reddit: https://www.reddit.com/r/castiron/comments/5rhq9n/the_rcastiron_faq_start_here/ https://www.reddit.com/r/castiron/comments/5rhq9n/the_rcasti...
- jrochkind1 8y ago
  The flaxseed oil method has worked great for me so far. But it is indeed a great internet debate. :)

pmoriarty 8y ago

Dough is edible glue.

twic 8y ago
All glue is dough if you're brave enough.
kaybe 8y ago
For better glue I recommend gummy bears as raw material. Starch-based ones are more brittle. (Disclaimer: I am probably not the best gluemaker.)

H1Supreme 8y ago

The technique described as "They overlaid many thin layers of oil paint" is technically called glazing. And, by "thin" layers, they mean a layer that is mostly oil, with varying levels of pigment. Many of the old masters would paint a detailed, monochromatic underpainting, and glaze many layers of color on top of it. Definitely not a process used by people who want to finish quickly.

gknoy 8y ago
That's interesting, it's very similar to the way many comics are done -- one person does the drawing and inking, and it's often colored by a different person (or at least as a different process if the team is small).

mwexler 8y ago

This extract is from Delancey Place, which sends a daily email with a para or two from a fascinating book. I am rarely disappointed with their choices. Affilitate link to buy book is at bottom of email, but they seem to invest far more heart in this effort than the revenue would support. Sometimes, curated discovery is just what you need in a rushed morning. Very recommended.

mauvehaus 8y ago

Paint, as understood by oil painters and artists, sounds like a slightly different animal than paint as understood by house painters, wood finishers, and other sorts of people with more prosaic requirements of their paints. Bob Flexner wrote a book for wood finishers, Understanding Wood Finishing, that breaks down oil paint in simple terms for the rest of us: Some oils (like linseed and walnut) are drying oils, and can be used as a finish on their own, but don't really form a hard film finish. For that you need a varnish, which is an oil cooked with a resin. Paint is a varnish with a pigment added. That's different from an oil mixed with a pigment mentioned in the article, which is probably fundamentally similar to a straight oil in terms of its properties. Maybe somebody who paints with oil paints can weigh in? His columns in Popular Woodworking and other woodworking magazines are worth a read, as is his book, if you're interested in understanding what you're really working with. Tying this all back to the article, I'd disagree with the claim that paint is "colored glue". One typically doesn't glue things together with paint, though that is a sometimes unintended consequence of putting something on top of something else with an incompletely cured layer of finish. You certainly couldn't use e.g. linseed oil as a glue in a joint where oxygen isn't getting in readily like a mortise and tenon joint. A discussion of oil vs varnish here: https://www.popularwoodworking.com/techniques/finishing/oil-finishes-their-history-and-use/ https://www.popularwoodworking.com/techniques/finishing/oil-...

abakker 8y ago
Not a direct response, but in the case of modern automotive paints, especially 2 part urethane or epoxy ones it is exactly right - they're even based on the same chemicals! Of course, that doesn't really mean that paints work as glues, but you can add pigment/dye to a lot of glues and get a workable paint. (workable in the sense that they will adhere and color. they may not have the consistency that makes them work well as a paint).
frontloadpro 8y ago
The Chem Engineer finds terms like Resin, useless. It's kind of like saying, tape. Which tape? Easy peel? Or duct tape? I imagine that this is possible because there is only one type of resin that's useful in this field. Or trade secrets...

hjk05 8y ago

Cars are Red. (Not true in general but true for a subset, which does not make it true in general) So no, cars aren’t red and pains isn’t glue.

qubex 8y ago

I run a paint production company here in Italy (decorative for interior/exterior house use, and various kinds of high-grade industrial coatings) so this article (not to mention the fact that it somehow climbed it was to the top of the front page) amuses me no end. I've forwarded it to all of my colleagues and they'll all in stitches too. Because basically deep down we know this is the most succinct and relatable description of what we do with our lives. Try as we might to aggrandise things, this is the truth stripped bare. Unvarnished truth, even. ;)

amarte 8y ago
This article is really interesting and I love the insight provided about pigment layering to achieve remarkable effects, however I think what the title says is totally wrong. Paints are technically coatings and comprise a large and diverse industry of products for wide-ranging applications. Wall paint is very different than artist paint, which is very different than car paint, which is very different than the type of paint you might apply to pipes to prevent corrosion, etc.. Glue is an adhesive, and while the resins used to make adhesives may sometimes be the same resins used to make coatings (Gorilla glue is epoxy-based, and many floor coatings you walk over all day and never think about are epoxy-based as well), the actual products being used -- the can of paint or the stick of glue you buy at the store -- are formulated with resins, pigments, additives, binders, chain-extenders, fillers etc etc, that are specific to the product's unique application. So basically, paint is not glue. Paints are coatings and glues are adhesives. Sure, paints have to adhere to their substrates, and adhesives must adhere to their sometimes very different substrates as well, but paint and glue are really totally different things. You could say that coatings and adhesives are both formulated polymeric systems, but you miss out on a lot of interesting subtlety that entire industries are based on when you say "paint is glue."

mxfh 8y ago

"The effect of layering is so powerful that it has transcended its roots in painting with oils and is now incorporated into all professional digital illustration tools. If you use Photoshop, or Illustrator, or any other computer graphics tools, you'll be making images in layers." The layering described there, is more about what blend modes are for, layering can also be quite dumb by itself. The roots of DTP software layers lie pretty much all in the necessities of print, not painting, where you have to have a layer per color anyway. Wondering why the article stops short of the point, why (digital) reproduction of paintings is a lossy process in general, and especially for archiving. Total Appearance Capture systems exist but are rarely applied to paintings. A 2D-RGB raster can only represent the appearance of a light reflective object from a single angle und very specific ambient conditions. How a painting interacts with light in a room is a complex process of all kinds of optical phenomena (reflection, absorbtion, diffraction, refraction ...) as described in the arcticle.

Syzygies 8y ago

Labor has become more expensive than parts, for many aspects of home repair. We haven't adapted our habits to this. The last time I let my university landlord paint my apartment, it took days to clear the furniture, and I was instructed to do no paint prep. There were peels coming down from the ceiling. The painters exploited this "paint is glue" theory by painting under the peels and pushing them flat. I channeled my desire to kill them on the spot by politely escorted them out in mid-job and never letting anyone paint for me again. The next time I painted this apartment, I stripped the ceiling bare of its many poorly applied layers, and applied $500 of artist-grade acrylic primer and titanium white paint to the ceiling and walls. 15 years later, the apartment looks just-painted. Artist-grade acrylic paint is one of the best glues available, much more reliably so than oil paint. In the years since, the best wall paints have come closer to artist-grade acrylic paints, and their glues are likely better tuned to typical conditions. Artist paint is more expensive and better. Carefully tuning a cheap glue is like botching an airplane hardware design and trying to fix it in software. Later in a home, filling holes in contractor botched cabinet work, I started with artist-grade acrylic modeling putty, added just enough dye from the commercial paint manufacturer to match the existing cabinet paint, tweaked the gloss to also match, and created a one-step wood fill that disappeared into the existing paint job when dry. Much less shrinkage than commercial wood fills, and no primer or repainting needed. Again, acrylic art supplies making the best glue.

drawkcab 8y ago
Did you apply any mud to smooth the surface before you painted the apartment?
- Syzygies 8y ago
  As needed, but once I got to bare concrete/whatever it was remarkably smooth. I chipped off the ceiling slowly over weeks, avoiding gouging.
  - HillaryBriss 8y ago
    what about lead? how did you handle the old lead paint layers?

deleted 8y ago

[deleted]

shutDeeFuckUp 8y ago

Eat my fuck.

Daub 8y ago

One point the article missed is the relationship between Canvas, primer, medium and oil paint. All three are traditionally derived from the same plant: flax. For this reason, there is great chemical compatibility between them, which accounts for their longevity. Even longer lasting is Buon fresco (the earliest form of fresco). This is essentially pigment painted into wet plaster. The paint is not a glue, rather a stain. Effectively the support and the paint are one. Another interesting point is the difference between how light paint is applied to dark. Light paint is usually painted quite thickly, and for this reason is very good at reflecting light. This improves the upper registers of the painting. The last thing you want dark paint to do is reflect light. Thickly applied black paint takes on a very 'flat' look. An experienced oil painter would apply black paint as a very thin and 'dry' layer (dry = no or little medium). They are also likely to employ an underpainting layer of brown-red. Applied in this manner the darks have a profound depth. The end result is a profoundly wide dynamic range.