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Repost: Glazing

First pub­lished on 1 Octo­ber 2006.

Among oil painters, there seems to be a com­mon mis­con­cep­tion that glaz­ing is some kind of mys­ti­cal tech­nique that only a few can mas­ter. The basic process is, how­ever, very sim­ple. Glaz­ing is putting one layer of paint over another so that you can see the under­layer through the upper layer of paint. Glaz­ing is a form of indi­rect paint­ing, which just means that you are paint­ing with more than one layer, allow­ing pre­vi­ous lay­ers to dry before you add more paint on top.

Glaz­ing can be used for a num­ber of pur­poses. As I noted my post com­par­ing the glaz­ing meth­ods of Ital­ian and Nether­lan­dish Renais­sance painters, glaz­ing can be used to cre­ate opti­cal color mix­tures (a blue glazed over a yel­low makes a green) or to cre­ate mod­el­ing effects (thicker lay­ers of trans­par­ent paint are darker, so you can adjust value by adjust­ing the thick­ness of the paint). Some artists glaze over a whole paint­ing to unify the over­all tone. Oth­ers will glaze spe­cific parts of the paint­ing. One method is to do an ini­tial monot­one under­paint­ing (in shades of grey, for exam­ple) then apply color over it. This sim­pli­fies the process of paint­ing by first tack­ling pure value, then work­ing out hue and chroma. Some mod­ern por­trait painters will do an ini­tial paint­ing of flesh in shades of green (they incor­rectly call this a “ver­dac­cio”). They then glaze with reds and oranges (com­ple­men­taries and near-complementaries to green), pro­vid­ing the flesh tones with a sense of vital­ity that is dif­fi­cult to achieve with direct paint­ing. Glaz­ing can also be use­ful for main­tain­ing chroma in light col­ors. Mix­ing with a lot of white will seri­ously reduce the chroma of most col­ors, result­ing in a look often described as “chalky.” If you glaze the same color over white, how­ever, you can achieve an opti­cal effect that is high in value, with more chroma that you could get by mix­ing that color with white.

Because a glaze dark­ens what it cov­ers (unless it’s a scumble—see below), it is best to do the under­paint­ing lighter than the intended final effect. If you are going to glaze, it’s impor­tant for the under­paint­ing to have as smooth a sur­face as pos­si­ble. That’s because irreg­u­lar­i­ties will trap excess amounts of paint in the glaze layer, cre­at­ing weird lit­tle spots of darker paint. So, before the paint dries, it’s a good idea to go over it very lightly with a soft dry brush, look­ing for lumps and gen­tly brush­ing them down. After the under­paint­ing has dried thor­oughly, you may want to wet sand to cre­ate as smooth a sur­face as possible.

In select­ing paint col­ors to glaze with, it is use­ful to dis­tin­guish among opaque col­ors (like cad­mium yel­low), semi-transparent col­ors (like ultra­ma­rine blue), and trans­par­ent col­ors (like alizarin crim­son). While any of these col­ors can be used for glaz­ing, trans­par­ent and semi-transparent col­ors are darker when they are put on more thickly. Opaque col­ors can be used for glaz­ing, but only when they are applied in a thin layer. A thick layer of an opaque color is not a glaze, because you can’t see the under­paint­ing through it.

Many oil painters think that the best way to glaze is to dilute the paint with medium to a watery or syrupy con­sis­tency (this is what a lot of art instruc­tion man­u­als tell you to do). The paint becomes less opaque because the pig­ment par­ti­cles are sep­a­rated by a larger than nor­mal amount of trans­par­ent vehi­cle. This type of glaze is called a dilu­tion glaze. In my (deeply hum­ble) opin­ion, it’s the wrong way to glaze. It’s bad tech­nique for (at least) three rea­sons: (1) all of that extra resin and oil will darken and yel­low over time, ruin­ing the effect; (2) dilu­tion glazes tend to cre­ate a sort of “tinted pho­to­graph” effect that doesn’t have the solid­ity a painter is usu­ally try­ing to depict; and (3) the doc­u­men­ta­tion I’ve found on his­tor­i­cal glaz­ing tech­niques sug­gests that only small amounts of resin are detected in glaz­ing lay­ers in Renais­sance Nether­lan­dish paint­ings, which I con­sider to be the gold stan­dard in glaz­ing for both beauty and longevity.

A bet­ter method is called a reduc­tion glaze. This approach involves adjust­ing the trans­parency of the paint by adjust­ing the thick­ness of the paint layer. While you can do a reduc­tion glaze with noth­ing but pure oil paint, it helps to first lubri­cate the sur­face by apply­ing a very thin layer of a slip­pery medium. My pre­ferred glaz­ing medium is a 50/50 mix­ture of black oil (lin­seed cooked with lead) and Venice tur­pen­tine (if you don’t like to use sub­stances con­tain­ing lead, lin­seed oil will work almost as well). Stu­dio Prod­ucts also sells an excel­lent glaz­ing medium. You can also use plain lin­seed or wal­nut oil as a glaz­ing medium. Put a drop of medium on the sur­face, rub­bing it in with your fin­gers to spread it as far as pos­si­ble. This way, you can cover a large area with just a few drops of medium. In addi­tion to putting some on the sur­face, you can also put just a tiny bit of medium in your paint, but I don’t usu­ally find that necessary.

Mix up the color you want to glaze with. Apply it thickly and evenly to the desired area with a brush. It will look like a hor­ri­ble mess at this stage, but have faith. You will now reduce the thick­ness of the glaze to the desired opac­ity and value. Do this by dab­bing with a soft brush, smear­ing with your fin­gers, rub­bing with a cloth or sponge, or what­ever works to adjust the glaze to achieve the desired effect. With a lit­tle prac­tice, a reduc­tion glaze is really pretty easy. You can get nice gra­da­tions in color and value by cre­at­ing a gra­da­tion from thin to thick. Or you can cre­ate gra­da­tions from one color to another. Once you have the glaze spread to the right thick­ness, you can, if you like, paint into it with other col­ors. For exam­ple, you can apply light high­lights into a wet glaze and then blend it in. If desired, you can let your glaze dry and then add one or more addi­tional lay­ers of glaz­ing. For exam­ple, you can get really intense, chro­matic darks by glaz­ing with mul­ti­ple lay­ers of trans­par­ent paint.

When mix­ing col­ors for a glaze, it is some­times help­ful to add a small amount of white to your mix­tures. This pro­vides a greater sense of solidity.

If you glaze with very light col­ors con­tain­ing a lot of white, it is usu­ally called a scum­ble. Tita­nium white, being very opaque, can be a bad choice for scum­bling. Flake white and zinc white are much eas­ier to cre­ate trans­parency effects with. A very white, hazy glaze is called a velatura (“veil”). A velatura can be a great way to depict trans­par­ent smoke, haze, or fog.

Update

Instead of mak­ing sure the under­paint­ing sur­face is smooth before glaz­ing over it, you can delib­er­ately give it lots of tex­ture. Then the glaze will sink into the nooks and cran­nies, cre­at­ing a sense of dimen­sional relief. Rem­brandt often used this technique.

Posted in art materials, art technique, oil painting.

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11 Responses

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  1. Incompetent says

    Some­thing I wish I learned ear­lier is that glaz­ing by itself rarely works, and a paint­ing often needs more opaque areas or else it will look insub­stan­tial. It also took sev­eral months for me to learn that Jerry Gar­cia was dead.

  2. David says

    @Incompetent -

    I agree. A mix­ture of opaque and trans­par­ent pas­sages cre­ates the most vivid illu­sion of real­ity, over­all. Adding a small amount of white to glaze mix­tures tends to reduce the “tinted pho­to­graph” effect that glaz­ing can produce.

  3. SPQR says

    JMW Turner was apt to use pure glazes, in his dark areas, and lat­erly in his colours too. ..though he was hardly attempt­ing a vivid illu­sion of real­ity. Also Velasquez (at least in the NG in Lon­don) used pure colour glazes (espe­cially the crim­son and turquoise-blue) over a neu­tral grey UP.
    Rubens paint­ings, in the same gallery, have glazed umber shad­ows over a lighter impri­matura.
    Too my eyes, these painters did not add white too these glazed areas.
    If this is the ‘tinted pho­to­graph’ effect, i like it :)

  4. David says

    @SPQR -

    SPQR,

    I’m a big fan of glaz­ing. For the most part, the artists you cite (except per­haps Turner) used a mix of opaque and trans­par­ent pas­sages in paint­ing. The tinted effect is most notice­able if you use it over large areas, or if you don’t know what you are doing. All of them cer­tainly did know far more about paint­ing than I do. Nev­er­the­less, for us reg­u­lar folks, it is all too easy to get glaz­ing effects that are uncon­vinc­ing if you are not careful.

    A tiny addi­tion of white is not par­tic­u­larly notice­able, to anyone’s eyes. That’s par­tic­u­larly the case with flake white, which is what all of those painters used. I don’t know that they mixed white into their glazes—I expect they did so some­times, but not other times.

  5. michelle says

    Thanks so much for repost­ing this!

    I have been strug­gling with glaz­ing to some suc­cess — (and some­times not). I’ll be try­ing a few of these tech­niques out immediately.

    Very grate­ful. :)

  6. Sandy says

    I have only been paint­ing for a short time and I’m very inter­ested in learn­ing more about glaz­ing. I am find­ing quite a bit on the internet…but I am left with ques­tions. I have been using Liquin mixed with trans­par­ent paint…such as Alizaron to glaze cer­tain parts of my paint­ing. Can I then wait for the glaze to dry and con­tinue to paint…and then glaze the entire paint­ing again or a por­tion of the paint­ing… How many times can I apply glaze and then keep painting…will it add depth? Do I use the same color of glaze…or can I use an Alizaron as the first glaze and then add a blue glaze to get a pur­ple glaze? I’m obvi­ously confused :)

  7. David says

    @Sandy -

    Sandy,

    You can cer­tainly glaze mul­ti­ple times, let­ting the paint dry in between. And there is no rea­son why you have to use the same color from one glaze layer to the next. They will mix opti­cally, so that blue glazed over yel­low will make green. Just be aware that trans­par­ent glaze lay­ers absorb light, so mul­ti­ple glaze lay­ers darken the value of that sec­tion of the painting.

    There’s no iden­ti­fied limit to how many lay­ers you can glaze, espe­cially if you keep each layer very thin.

    Note, how­ever, that one of the rea­sons I don’t use alkyd paint­ing medi­ums such as Liquin is that I have heard a few scat­tered reports that it can cause paint lay­ers to peel away, espe­cially when glaz­ing. Other artists report no prob­lems whatsoever.

  8. Annne Fontaine says

    Great entry! I used lin­seed oil two days ago and wor­ried that it will never dry. It will dry, cor­rect? I am sub­scrib­ing to your feed…I guess that is how it is done, to get updates. Your feed….I feel like a pig at the trough. lol I have a gallery and stu­dio, I paint peo­ple, not lit­er­ally. I do thick paint­ings, I do thin paint­ings. Lately with the thin ones I have been glaz­ing a LOT. come see me, either on the web or for real, if you are near NH. :) http://​www​.chameleonart​.biz

  9. davidrourke says

    Anne,

    Lin­seed will cer­tainly dry—of the dry­ing oils in com­mon use (lin­seed, wal­nut, poppy, saf­flower) it dries the fastest. I rec­om­mend apply­ing it to the paint­ing sur­face in a whis­per thin layer before glazing.

  10. Julius Gordon says

    David: In the beau­ti­ful work you show on your gallery, are most of the effects achieved with your “thick glaz­ing” tech­nique? I have been exper­i­ment­ing with thin glazes and have run into prob­lems at every turn. For exam­ple:
    How to achieve an intense red or orange, since cad­mium col­ors are out?
    How to glaze thinly and be able to do fab­rics and table­cloths — espe­cially in light col­ors?
    How to do a light color ceramic bowl (as in one of yours)?

    Maybe you could speak in detail about the work in your gallery…

  11. davidrourke says

    Julius,

    Thank you. I’ve answered your ques­tion in a sep­a­rate post.

    http://​rourke​vi​su​alart​.com/​w​o​r​d​p​r​e​s​s​/​2008​/​11​/​29/q



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