G L A Z I N G :
Glazing is probably my most favourite and used technique. It is a technique that uses a medium to "dilute" the paint so there is just enough pigment to create a tinted tone that becomes a semi-transparent layer you apply over other dry opaque layers (usually lower in chroma/less saturated). This semi-transparent layer changes the tone/colour, value, depth, and luminosity of the layers beneath.
When there are multiple glaze layers, the colours optically blend as if they were all combined without the pigments actually mixing. This creates an interesting effect as light passes through each glaze layer and illuminates the layers- which is very effective for portrait painting, or trying to capture light. Glazing comes to play is when you see the glowing effect of a Vermeer painting.
As there are many layers of paint, care needs to be taken in relation to the fat over lean rule. Each subsequent layer of paint should have more oil than the prior layer to avoid cracking in the paint.
Many painters use both thin glazes and thick, impasto brushwork to create a variance in the painting. The impasto areas would appear pushed forward in the painting compared to the softer glazes. If you avoid using fats that are just oils, and avoid leans that are just solvent, and instead use mediums that fall in the middle like glakyd/galkyd Lite, Liquin/Liquin Fine Detail, Impasto, g-gel, then you can worry less about these rules. These mediums fall between a fat and a lean while offering great flexibility, and when added to paint, they all make it more transparent the more you add. Use galkyd or liquin options if you're looking for smooth glaze layers, and impasto or g-gel if you're looking to make your semi-transparent layers textured. You can use a combination of these to accentuate certain areas. Here's a look where I used flat glazing everywhere except for the knuckles, where instead of rendering knuckle creases, I opted to impersonate them with texture:
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After rendering the tones through multiple smooth glaze layers with liquin, I then smooth glazed redness on the knuckle where the hand punched through the canvas and was red as a result. Giving the illusion of that red hue through transparent skin. (would otherwise fall flat if I painted it red instead of glazing.)
Then I added an impasto layer of lighter tones to create textured detail for some painterly dimensional interest.
You'll want to make sure you're building up your details in each layer so that by the time you are done the last glaze layer, all that is left is the final thin details like hair strokes, and specular highlights (your brightest and highest points on your canvas). Glazing makes the canvas surface slick, it can become almost enamel like depending how many glaze layers you use and how transparent they get. This makes it difficult for the paint to adhere to the surface, so you wouldn't want to do any corrections at this stage, however fine marks/ details will go down okay.
When glazing smooth over textured areas, make sure not to have it too fluid- it should be more like you're scrubbing it on. This is b/c if it's too fluid on the surface, you get a build up of tone in the creases of texture, making it inconsistent as it pools up in the valleys, the tones will be more saturated, and on the highest parts of the texture it will be thin and less tinted. Unless you want to utilize this as a technique to your advantage (could have neat results in certain subjects).
One important thing to note is that the mediums I listed above to use for glazing can yellow overtime, so you don't want to ever just use them without paint. (the fluid mediums when used without paint, and in a thicker coat will yellow, and bead up, and make your painting look like shit. impasto without colour will start clear, then yellow over time giving yellow texture wherever you put it. So white oil paints also tend to yellow a fair amount, so when you're painting if you want to use white with one of these mediums near the end, maybe opt for a cool white so it neutralizes a bit as it ages. Since these mediums do yellow, they work best for warm glazing options. If you're glazing in cool tones, think of how it will age (it doesn't take that long- it can start showing yellow within a year), so mitigate this by using less glazing for cooler areas, or add a tone to offset the yellow tint so if it does get a bit yellow, then it still reads as the correct tone. Now since these do yellow with age, you'll also want to keep in mind where on your painting you're glazing... if one part yellows at a faster rate than another, will it throw your piece off? account for this while painting.
When glazing it is best to use paints which have a more translucent quality, as opaque paints tend to muddy the painting and do not yield the desired results. White for example is not great for glazing as it is very opaque and would make everything hazy and chalky looking, since it is also cool, it would blue things out, desaturating the colours beneath it.
where as alizarin crimson creates beautiful rich semi- transparent glazing.
you'll quickly see which paints are better suited for glazing and which aren't as you experiment, but to help you get started, heres a list of colours well suited for glazing and a list of those that are not, and the ones somewhere in between:
Well suited for glazing:
-Transparent Earth Red (exceptional for glazing)
-Transparent Earth Orange (exceptional for glazing)
-Transparent Earth Yellow (exceptional for glazing)
-Asphaultum
-Alizarin Crimson
-Paynes Grey
-Chromatic black
-Hansa Yellow
-Indigo
-Burnt Umber
-Sap Green
-Black Spinnel
-Green gold
Phthalo Green
-Phthalo Emerald
-Prussian Blue
-Ultramarine blue
-Van Dyke Brown
NOT well suited for glazing:
-White (of any sort)
-Naples Yellow Light
-Terre Vert
-Flesh Tint
-Mars Black
-Portland greys
-Titanium Buff
-Radiants
-Raw Sienna
In betweenies for glazing (some are better suited in some areas and not for others):
-Black (Lamp, Mars, Ivory)
-Yellow Ocher
-Cadmium orange
-Cad Red
-Raw umber
-Olive Green
-Cobalt Green
-Venetian Red
-Viridian
If you can't tell by looking at the paint if it will be a good glaze option or not, check our Gamblins Colour Chart
I highly recommend their paints as your choice of oils (It's what I use), and here they don't just show you all their colours but if you click any of the colours on that page, it will show you if it makes a good glaze or not, and if so, how it looks as a glaze.
This will be great to reference until you get a better feel for this technique and begin to understand your oil colours.
If you've found that you laid down a colour with too much intensity, or the wrong colour, depending on your application, you can totally remove the glaze without it having affected the painting beneath it. The best way to take advantage of this is by using liquin or galkyd in each layer you do. Wait at least a day between each layer (make sure its dry before you paint over it) The more medium you use, the more it sort of seals that paint in, making it less and less impenetrable to staining of glazing. Instead of the glaze layer soaking into the paint, it sits on top of it. This technique also yields itself to paintings with more depth, as the light passes through all these layers that work in harmony to produce the final image. But the more of these glaze layers you do, the more it becomes unworkable if you need to make crucial changes. This is why your underpainting is so important. Get it right before you start glazing, and you can take advantage of its benefits without having any cons.
Knowing how many glaze layers to use will come as you learn. For me I just keep adding them until I get to a point where it is no longer being improved by it, but starting to look worse. And at that point my painting is more on the slick/enamel like side, so that I can remove this ugly glaze layer no problem, and stop there, and start adding my final details in to wrap it up.
The most important key to understanding what a makes a glaze layer good, and how to properly use this technique is in understanding your colours and how they operate when using these semi-transparent layers. The same colours you use together wet on wet, or wet on dry look totally different when you are laying a wet, semi-transparent glaze layer over a dried colour.
It's very important to note that glazing is best used to enhance the vibrancy of a colour, and to slightly darken a value.
You CANNOT lighten an area using a glazing technique without it looking cloudy/muddy and changing the tint to that hazy light blue (even if you use lets say a naples yellow light paint to glaze over any other colour, you still get something that looks like a light pale chalky baby blue). So with this knowledge you know to make your underpainting a little less vibrant and a little less darker in values than how you want it to look when finished. BUT you are limited in value and tonal correcting and building to the colour beneath and how it reacts to that glaze colour and tone. So lets say you're painting a face and you massively undershot the shadow values and didn't realize until later on and try to darken it by several shades in one go- this wont work very well. You're better to slightly darken as you go over multiple layers. So that's the limitations and approach to value, but when it comes to tonal correcting or enhancing with glaze layers its best to imagine those semi-transparent coloured plastic sheets you use over a camera for different "filters"... lets say you start with a yellow filter, and you overlap a red filter... the overlap will be an orange. This is a nice easy clean colour. But lets say you're starting with a yellow filter and overlap a purple filter, you're going to get a muddy colour thats still rich in its opacity, just not quite nice (vs if you actually mix yellow paint and purple paint, you get a totally different colour and opacity than when its a "filter" or glaze layer.) So when painting your first block-in layers before you get to glazing you'll want to anticipate what colours you'll use to glaze over and how they will react to the base you have. You need to think ahead several moves and see how all the different layers of colour will come together for the end. It sounds more daunting than it is once you understand it though it comes more naturally.
So lets take a look at a portrait painting, for your block in, you'll mix skin tones as you see them, but slightly more pale, and slightly less in value. Usually this happens naturally if you're actually trying to mix what you see, b/c by the time you blend it together in your underpainting it gets a bit washed out. This is good! it sounds fucked, but having a portrait that looks flat and a little like the person is dead with flesh thats lacking those tones that happen as blood is coursing through us ...Think back to any film showing a corpse... its pale, and bluish, and grey... not "life like"... This is my preferred base to build my glaze layers from. Since it's easier to glaze warm tones, but flesh tones do have blue to them, its best to start with a blue/ grey dead skin tone (not actually blue... like don't paint your piece in blue/grey... actually try to mix flesh tones... the blue grey will happen naturally with blending the wet paint if you've used white- which you should have).. so then I don't have to worry abut adding blue in later and can focus on just building up my pinky/red/orange glazes that really bring the flesh alive. Now you'll want to look at the flesh tone in question- is the skin a little more yellow (use transparent earth yellow in the mix) is it a little more olive? (add a green glaze layer, or mix green into your red glaze). Skin tones shift massively even within one person on one small part of their body.... take a look at your hand right now... see how many subtle tonal shifts there are? So if you start with your base colour, you can then glaze on these tonal shifts to look nice and harmonious, focusing on tone instead of value or form since that will already be laid out for you in your underpainting, and since these are transparent layers, it's just tinting whats there.
Okay what happens if you've overshot and it looks way too high in chroma (too intense in colour), well you may be able to make quick adjustments by doing a glaze layer in its counter colour, or a tone that will neutralize and desaturates.
The great thing about glaze layers is that they don't take long to paint, but you do want to work with several and they will need dry time between, so this allows you to make small more subtle changes, forces you to step back, and assess it again with fresh eyes the next day. So you're never making too intense of changes that can't be corrected to some degree.
If you're having a hard time getting the glaze to be smooth, it could be the brush you're using- for smooth glazing you will want a softer brush, and for larger areas to get a consistence tone, use a mop brush (some times dabbing motions with the mop brush work better than dragging it smoothly across). Stiffer bristled brushes such as hog hair, may be working against you as they "scrape" the glaze back and leave it streaky.
GLAZING VIDEO COMING SOON.