油画技法知识

油画作为一个体系完整的画种，先是服务于封建体制落没后的新兴贵族的家族生活、社交生活和政治生活，以肖像画或情节性肖像画为主。伟大的拉斐尔就是以理想化的架上肖像画闻名于世的。这一时期也产生过杰出的宫廷画师 ，比如荷尔拜因。后来这个画种的题材逐渐以神话、宗教、战争、市俗风情、现实情态等内容为主，再后来又以层次、语汇、结构符号为关注点，形成了人类文明版图上的最色彩纷呈的一个王国。油画的长期繁荣离不开它的物质基础——油画的材料。而这须从整个的绘画物质基础来谈起。

（一）绘画材料的分类介绍

1、胶

能氧化凝固，在一般温度下无法再变成流体的胶叫不可逆转胶。用于油画底子的胶必须是可以固化的不可逆转胶。底子不宜厚涂，加水4-5倍为宜。不可逆转胶胶在绘画的用途，另外的还有作水溶性颜料的粘合剂；作画作表面的上光料。不可逆转胶有植物胶、动物胶、酪蛋白胶、甲其素和白乳胶。

植物胶

主要用于制媒剂。不宜熬煮，用二十五倍开水冲沏即可。阿拉伯胶与亚黄蓍胶需先加少许酒精搅拌后，再加水。

动物胶

有皮胶、骨胶、鳔胶、鹿角胶等。冷水泡一昼夜，加热至60℃进行搅拌，胶与水的比例1∶10。

酪蛋白胶

即干酪素胶，二十世纪才开始使用于绘画，化工商店有售。

甲基纤维素胶

可当作白胶用，化工商店有小包出售。

白乳胶

成分是聚乙烯醇缩甲醛。从五金店中买到的白乳胶的水、胶比例已经是1∶4了，可直接刮到基底上。

可逆转胶也能在绘画中发挥作用：明矾可防腐，每一千克胶液可加10克明矾以防腐（数滴石炭酸、杨酸、或6∶125的硼砂水也可代用）；甘油和蜂蜜可用作加固、防裂。）

2、油

干性油遇氧会氧化凝固，媒剂油必须是干性油，重要的干性油有亚麻油和核桃油。但灶火烧制的亚麻油、核桃油并不附合作画的要求，因为它们已经氧化成固体了。可是生的亚麻油、核桃油又氧化得太慢，没有粘固能力。所以符合要求的只能是半熟的。半熟的亚麻油是调色油的主要成分。怎么制出来半熟的亚麻油呢？方法是将亚麻油盛到广口玻璃瓶里，口上封盖纱布，置于通风处曝晒一二个月，油液就会变得透明纯净、油质浓厚。油质的变浓是因为氧化作用的结果。将生核桃油变成半熟的办法同上。也有人用低温加热的方法处理生核桃油（见第二部分伊威尔一节）。花生油、豆油等不是干性油，没有固化作用，不符合绘画的要求 。

松节油是最常用的油彩稀释媒介剂，由松脂蒸馏而成，药用的要纯于工业用的。纯净的汽油倒是可以代替松节油，但问题是它总是杂质多，挥发过快。所以最多只能用来洗笔。

光油关键物质是树脂，光油所含树脂不纯会使作品昏暗。配制光油的用油可以是干性油，也可以是挥发性油。但是汽油不行，它杂质太多。通常用的松节油。光油里头，松节油同树脂的比例是2∶1，而要用这两种东西配合成媒剂的话，比例应该是3∶1，玛蒂脂和达玛脂是用于光油的两种上乘树脂，前者较昂贵，国内不产，后者也可用中药店里的“生乳香”代替。

半光光油 加了蜂蜡或硅石（Sio2）。蜂蜡不超过1/4。

速干油

制法是把亚麻油或核桃油倒入浅盘中，盖上玻璃板，曝晒三五天即可。

慢干油

丁香油滴入调色油，可使干的慢，也就是说滴入丁香油的调色油就是慢干油了。

重画光油

成分里头有天然树脂和丁香油，如果不是在紧急情况下在不该中断的地方中断绘制，一般用不到它。

3、颜料

在笔的运动下，颜料颗粒如果相互粘连成较大的颗粒，则画面透明性减弱（大颗粒颜料反射光线混乱，会使画面发乌，变得昏暗）。工笔画中罩染前先用矿物色渲染，就是因为这类颜料颗粒不易在盖色时上翻。

油画要在头一遍颜色干好（大约需要10小时）后才画第二遍，是为了防止吸油。没有“釉料”的颜料层会毫无光泽。

4、树脂

树脂（达玛树脂、马蒂树脂）彻底氧化凝固后，油画的表面就结有一层光泽的固态釉质。它的来源一是半熟的干性油，一是将现成树脂（用松节油）溶解而成的光油。就稳定性而言，后者好。绘画光油其实就是树脂比例小于上光光油的树脂与松节油的混合物。

树脂有胶固性，倒是可以缓解上下层的绞混。最先充分发挥树脂作用大大解放运笔的大师是戈雅。

5、其它

白垩

最古老的绘画材料之一。许多原始洞窟壁画是用白垩、木炭、红土画成的。

白

钛白易返；铅白怕油；锌的日久会变黄。铅白之所以怕油，是因为会发生轻度的化学反应。铅白用于丹培拉则很合适。

立德粉即锌钡白，成份为硫化锌和硫化钡。刷底子用得多了就是吸收性底子；用少了就是中性底子；一点立德粉都不用，只用胶或油性底料，那就是不吸收性底子。最不吸油的，是用油质底料作的油性底子了，能使画面出现很好的层积感。

木活榫

内画框内角和外画框的内角最好都设两个活榫，以便随温度变化而相应地调节松紧。

（二）由典型画家分析油画技法的实质

凡·艾克最早使用半熟的干性油和树脂的混合物来作绘画媒剂，也就是所谓的 “布鲁日光油”，俗称 “黄酱”。它不但使行笔流畅，还干得快慢适中，从而使油和颜料结合了。但凡·艾克并没能彻底摆脱丹培拉  。他先把白垩调胶刮涂到基底上，然后磨光，再在上面画上单色的丹培拉底色层（细笔排线）。在不吸收性的底子上画上油彩的底色层，是提香的创举，这是后话。可以说间接画法的首创是凡·艾克，直接画法的首创是提香。总地来说，油画发展到近现代、在材料、技法方面似乎有一个 “历史的回归”，不少的画家又开始重视步骤分明的间接画法（所谓古典画法），但他们要的精致，已不再是为了逼真，而是某种特有的画面质感。

凡·艾克的“黄浆”，是在晒稠的半熟核桃油、亚麻油中加入天然树脂而成，用以调色层层罩染（各层之间还需涂光油作结合层）。后来梅亚纳将这种媒剂的配制方法传入意大利。而意大利最早使用这个的，是米开朗几基罗的老师吉良达约。达芬奇《最后的晚餐》并没有使用油彩，不是油画，而是不成功的丹培拉壁画。

乔托的丹培拉底色层是用绿来画的，“三级色”罩染，羊皮胶作结合层。上光用的油很稠，被熬成原先体软的一半，是用手擦在干好的画上的。

格列柯（西班牙）在罗马得到凡·艾克的配方。他在媒剂中加入了少量的蜂蜡。

拉斐尔的架上画技法：第一步，以石灰作底子；第二步，在干好的底子下上用深色勾稿；第三步，抹一层石灰后趁湿用绿画底色层；第四步，底色层干好后，刷一层光油，再用类似凡·艾克发明的媒剂调色进行绘制，笔触较明显。

伦勃朗的技法：第一步，作灰色底子；第二步，潇洒地画单色底色层；第三步，用胶白（胶多水少的丹培拉调制的白）再画底色层  ，主要是在原来基础上原画亮部，加大明暗对比，注意，这种“胶白”干的比较快。第四步，用媒剂油罩色，局部掩盖住底色层。

伦勃朗一幅画用色不过数种。到了晚年，作画速度快得惊人。

鲁本斯的技法：第一步，逸笔画出生动的线稿；第二步，以媒剂油调色辅陈；第三步，趁湿深入，亮部厚涂，暗部半透出油性的底子，必要时用中间色重勾轮廓。

鲁本斯临摹提香和委拉斯贵支的画，都用自己的办法临，并且不求毕似。他的“一次过”画法即是纯粹的直接画法，是将油彩趁湿层层叠加的意思。鲁本斯是第二个摆脱了丹培拉底色层，并让素描与色彩同步的油画大师。第一个是谁呢，前面已提到了，是提香。像他们这种纯正的油画家，根本不屑于借助详细的底层素描。所以单从技法上看，凡·艾克还只能算是一个画匠，只不过他的“想象造型能力”又远远超过了一般的画匠。总之对凡·艾克这样的画家的观念和技法，应该分开来看，这关系到关于油画命运的判断。

籍里柯显然是用层层罩染的方法在作画，他所用多层透明画法（间接画法）照样离不开类似于“黄酱”的媒剂。

柯罗不用丹培拉画底色层，但他的技法显然不是一气呵成的直接画法。同时他的手法又异常丰富，经常依托于底色去罩色，有时是靠粗鬃画的笔干扫而透出底色；有时可能是调光油薄薄罩染；有时留出底层色正好是树枝什么的，弄的很巧妙，一切都事先计划好了似的，很有章法。

间接画法是分层画的，这似乎有利于颜色的耐久。德拉克洛瓦是用直接画法的，有人说他的有些作品（如《希阿岛的屠杀》）变暗是因为颜料配伍的问题，而我则认为其原因是媒剂不净，含有油和树脂之外的东西。

库尔贝在技法上有一个贡献，丰富了油画的语言，那就是他对于画刀的使用。当然他所刮的颜料是从店辅里买来的，是用媒剂配过的。库尔贝的时代已经不再需要自己配制颜料了。

波那是肖像画家，凡高受过他的指导，徐悲鸿出于他的门下。波那是趋于厚涂颜料的，并不注重分层的程序。直接的厚涂很容易降格为拙劣的涂抹，如果是那样的话，则与“直接画法”没有关系了。

封丹·拉·杜会弹钢琴，画画是使用分层法。先以细笔弄出有肌理的底色层，然后再薄色釉染。罩染时媒剂里有树脂，干后有透明坚硬的保护层，就可称为釉染。

德加早年用古典技法，中年恣肆，四十岁后衷情于色粉笔。当时的风气是直接画法大受欢迎。整个印象派，都是在做把“画法”从“做法”当中解放出来这件事，在德拉克罗瓦的旗帜之下进行了一次“直接画法”在新时代的复兴运动。

莫奈所用媒剂以松节油为主。那时从颜料工厂生产的颜料已然掺进了树脂。只用松节油也还因为他喜欢亚光的效果。

劳特累克喜在不掺粉的胶底上薄涂颜色。他的直接摄取的手法曾经把老年的德加感动得热泪盈框。其实真正的油画精髓在技法上就是直接摄取，具体说就是直接凭素描抓住色彩，或凭色彩抓住素描（体面），并把这个捕抓的过种保护留在画面上。

古欧洲丹培拉

1、蛋黄丹培拉：去膜与绒状胚的蛋黄加等份亚麻油、上光油，搅匀，再加一倍水搅匀，一两滴醋可有利于乳化。

2、全蛋丹培拉：鲜蛋去胚，加亚麻油、上光油和水，密封摇匀。

丹培拉的特点：

1、易腐。若无冰箱，最好只制当天用的。

2、干得快，干后反而非常耐久，不变色。

3、可加水稀释，但最多七、八倍的水，水过多的话，画好干好的画面还会被水溶解。

4、可调进多种颜料粉末，不怕产生化学反应的颜料配伍问题。

5、适合画在吸收性底子上，特别是白垩画底。

6、用丹培拉调色一层层地画，应先薄后厚。未干透时再加画丹培拉色层，得先涂一层丹培拉（没调色的），以防止底色上翻，同时也是为了两层间的粘接。干透了以后还要画的话，更得先涂丹培拉了。

7、油彩可加画在丹培拉底子或底色层上，却不可以相反。因为已画上去的油彩层不吸水，所以就不能再画丹培拉在上面。

以上就是传统丹培拉的配制和使用的情况。到后来，人们在丹培拉的制作中曾将鸡蛋（胶）改换为干酪素、骨胶、稞麦粉、肥皂等，现在的工业合成胶（比如白胶）也可以用。

十五世纪意大利湿壁画的制作方法：

1、将砂与石灰按2∶1比例混合，涂底子。

2、快速用赭石勾线起轮廓，用红色粉笔画底色层。

3、趁底色层未干，薄涂一层石灰。

4、趁湿用丹培拉调灰绿色去画暗部。

5、趁湿完成画面，用色的种类可以放开。

一，亚麻布

国内优质的亚麻布主要是用欧洲原产地（法国、荷兰、比利时等国）进口的优良原麻，经过严格的专业程序加工生产的。从面料的原料（纱）和纺织方法（剑杆机制造）来看，最讲究、最适合做油画支撑物的，是雨露麻，而双雨露麻（经纬向都是用的雨露麻纱）最为稳定。

国产纯亚麻布中，双雨露麻才是上品，用它做的画布并不比欧洲进口的成品布差到哪里（前提是底料和工艺过关）。事实上，国内有几家大型的亚麻布生产企业，每年都有大量用进口亚麻原料织成的优质亚麻坯布和经过染整后的亚麻面料出口到欧美。你买到的所谓进口画布，没准就是用中国生产的坯布加工而成（因为成本低），但价格会比国产高出不少。

自己手工做布，选择只经过定型和烧毛处理（亚麻布织好后表面有一层毛絮，有实力的大厂会作烧毛处理）的原色双雨露麻。市场很多所谓雨露麻，由于要有卖相，做了上浆处理，洗去浆后，表面会留下很多浮毛

鉴别的方法：

1，裁两块同样大小的布。

2，目测：表面光滑，织纹均匀，光面几乎没有跳纱和接头的，有亚麻固有光泽的，是大厂的长纤维好布。

3，手摸：手感滑溜，有自然垂感的，是好布。

4，称重：同样面积、同样纱支、同样风格的布，好布重量重，劣质布重量轻（劣质布为了掩饰这一点，同时为了表面光，通常会上浆，上过浆的布，重量会增加，手感会很硬）。做面料行当的，很重视“克重”这个指标（每平方米的重量，简称米克重）。应该注意，同样纱支（粗细）劣质的短纤维麻布，米克重也会很高，但它会看上去线纱粗细不匀，接头很多（从反面能看出来），布表面粗糙（浮毛很多）。

5，火烧：抽经纬两股纱线，分别烧。燃烧充分，几乎没有灰烬的，是优质纯亚麻布；灰烬多且发灰黑色的，有糊味的，是棉麻混纺布或其他混纺布，不适合作画布。

6，看价格：市场上雨露麻坯布，每米（门幅3750px左右）低于40元左右的，不可能是好布；相反，价格高的，也有可能掺假，要结合上述1-5鉴别。

7，纯黄麻（因为成本低，以前经常拿它做麻袋）织出的高密度粗纹布（手感硬）也凑合能用。价格比纯亚麻要低得多。

Not all tempera painters strictly use egg yolk as the binder for their paint. Here are some of the most popular recipes consisting of egg, casein and gum tempera shared by Russian and Ukrainian painters. What follows are formulas and instructions on making and using tempera and emulsion paints.

Note: Although, Natural Pigments has tested each of these recipes, we urge artists to test them for their application to determine if they are suitable for their use.

Egg Tempera

As the binder of egg tempera the yolk serves as a natural emulsifier, into which oil, resins and turpentine can be mixed.

Egg-Oil Emulsion of M. Dernera

Egg-oil emulsion produces a viscous paint that allows the finest brushwork for minute details in paintings.

How to Prepare: Break the egg and drop the contents and strain through two layers of cheesecloth into a small jar. Mix turpentine and bodied oil together, and pour this mixture into the jar in a very thin stream, continuously stirring until the oil is used up. An emulsion of egg and raw linseed oil will remain in suspension for some time, however, bodied oil may separate after one day. To preserve the emulsion from quickly becoming spoiled add a few drops of clove oil.

How to Use: Grind pigments (dry pigments that have already been ground into a water paste) into this emulsion and paint directly on gesso panels, diluting the paint with water as desired. Undercoats should be quite thin. Subsequent coats may be applied unthinned.

Egg-Oil Emulsion

While pure egg tempera does not allow you to soften or fuse colors, this recipe gives you some of the characteristics of oil paint in egg tempera.

How to Prepare: Break the egg and drop the contents into a small, clean jar. Add the oil, close the jar with a lid, and shake the contents vigorously until they combine completely. Add clove oil last as a preservative to help prevent quick spoilage. Strain the mixture through two layers of cheesecloth into another jar.

How to Use: This emulsion can be thinned with water and is less oily than other emulsions. Grind pigment paste into the emulsion, but only enough to use in one painting session. This paint can be used directly on gesso panels, or wet-into-wet on fresh oil paint.

Egg-Resin-Oil Emulsion of P. Kemerova

Here is an emulsion that embodies all of the qualities of egg, dammar and oil in one paint. The safflower oil is light in color, slows the drying time of this emulsion and yellows less than bodied oil.

How to Prepare: Separate the egg yolk from the white, discarding the white and placing the yolk in the palm of your hand. Pass the yolk gently from one palm to the other, drying the empty palm. When the yolk sac becomes fairly dry, pick up the yolk between your thumb and forefinger and hold it over a clean, small jar. Puncture the yolk sac and drain it into the jar, avoiding to deposit any sac into the jar.

Combine the oils and resin, then stir them into the egg yolk, drop by drop, until the emulsion is complete. Add water last in the same way to thin the emulsion as needed. To preserve this emulsion add a few drops of clove oil or Phenol solution (liquefied carbolic acid).

How to Use: Use this paint recipe to paint directly on gesso panels or for painting on a casein or glue tempera underpainting. Grind pigments into the emulsion, using only as much pigment as necessary for one painting session.

Casein Tempera

Hard and moisture-resistant, casein tempera makes a quick-drying tough paint.

How to Prepare: Use only fresh casein for this recipe, as it looses its strength if stored for long periods. Sift the casein slowing into half of the water, being certain to eliminate all lumps. When smooth add the borax and stir. Allow the mixture to stand about half an hour before you stir in the remaining water. Heat the solution to 180ºF (82ºC) for no more than 20 minutes. Careful not to exceed this temperature as it will denature the proteins in casein.

With a palette knife combine dry pigments directly with casein solution to form a paste. Mix the pigments well to ensure a smooth paint. Casein does not require the addition of a preservative since borax is already such. However, casein will not store for long periods, usually no longer than one week in the refrigerator.

How to Use: Paint directly on gesso panels with bristle brushes, taking care to keep the brushes in water when not being used and carefully wash them with soap and warm water after use.

Casein-Oil-Resin Emulsion

This emulsion produces a paint that is quick setting and allows thick, impasto in mixed techniques.

How to Prepare: Combine the bodied oil and dammar varnish in a bottle, tightly cap it and shake the contents vigorously. With the casein paint and dry pigments work up your colors on a palette or in a dish. Use a palette knife to grind each dry pigment to a stiff paste with the casein. Drop by drop, add the oil and dammar mixture to the casein paint. If necessary, add a little borax in solution to ensure that the oil-resin and casein combine properly. You can dilute this emulsion with water.

How to Use: Apply this emulsion directly to a gesso panel. You can vary this recipe by adding a greater percentage of oil-resin (up to two times the amount) for greater flexibility and slower drying time. This quick–drying paint will set up in 10 minutes or less and must be used while fresh.

Gum Tempera

Gum arabic, gum tragacanth, cherry tree gum and dextrin can be used as the basis of gum tempera and emulsions.

Gum Arabic Tempera

Water-soluble gums are a major constituent of watercolor paints because they are easy to make, non-toxic and quick drying. Gum arabic is none of the most commonly used.

How to Prepare: In a double-boiler heat the water and stir in the gum arabic. Powdered gum takes less time to dissolve than lumps, but complete dissolution still requires several hours. After the solution cools, cover and leave it until the solution is clear. Strain the gum-water through two layers of cheesecloth into a clean jar. Keep this solution refrigerated when not using, because it spoils easily. You may add a small amount of glycerin (no more than five percent) to this solution to reduce brittleness in the final paint film. Add a few lumps of camphor to this solution as a preservative or Phenol solution.

How to Use: Mix pigment paste with the gum solution into a thin paste and paint directly onto paper, parchment or gesso panels. For opaque paint, use a larger proportion of pigment to the gum solution. For transparent watercolor technique, thin the paste with water. When the painting has dried it may be varnished.

Gum Tragacanth Tempera

Gum tragacanth, unlike gum arabic, does not dissolve into a true solution with water. Rather, it absorbs water to form a suspension.

How to Prepare: Finely powdered gum tragacanth is available and is easier to use than lumps. Put the gum into a clean bottle and add enough alcohol to make a soft paste. Add the water last and shake it all together. Gum tragacanth requires about two days to absorb all the water and to swell in a mucilaginous suspension. Strain the suspension through cheesecloth into another clean bottle to obtain a more uniform consistency. You may add a small amount of glycerin (no more than five percent) to this solution to reduce brittleness.

How to Use: Make a paste of dry pigments and water, and mix with the gum solution into a thin paste and paint directly onto paper, parchment, canvas or gesso panels. When the painting has dried it may be varnished.

Gum-Resin Emulsion of A. Beklina

Use a gum arabic, gum tragacanth or cherry tree gum solution as the basis of this emulsion. Gum solution has a weak emulsifying force therefore it is important not to use more than 1 part oil or 2 parts resin to 4 parts of gum solution.

How to Prepare: Combine the Canada balsam and turpentine together in a clean jar and allow the balsam to completely dissolve with the solvents. Combine all ingredients at room temperature in a clean bottle; cap and shake vigorously to emulsify. For an oil-resin emulsion, reduce the amount of balsam and solvent by one half and add one part of bodied oil to the recipe.

How to Use: Use on any sized support—paper, cardboard, panel or canvas. Make a paste of dry pigment and water, and then combine with the emulsion and apply to the support with bristle brushes. Thin coats of paint will dry within an hour. Dilute this paint with water.

Collagen Glue Tempera or Distemper

Animal glue makes a very strong glue solution, which can be used as size, in gesso or as a quick-drying paint when mixed with pigments.

How To Prepare: Soak the powdered glue overnight then warm in a double-boiler—do not heat over 160º F—until the glue dissolves. Add alum (aluminum sulfate) to the solution to harden and preserve the glue, if desired.

How to Use: Keep the solution warm while you use it but never overheat it or warm it over direct heat. Make a paste of dry pigment and water, and grind this with a palette knife into the warm glue solution. Using bristle brushes apply the paint directly onto gesso panels. Painting in thin layers gives the best results as thick paint tends to crack.

Gelatin Tempera

Gelatin makes a low-cost, quick-drying paint and is ideal as a size for water gilding when mixed with bole or gilders burnishing clay for the best burnished finishes possible.

How To Prepare: Soak the gelatin in water for 15 minutes or until the gelatin swells. Heat in a double-boiler until the gelatin dissolves. Add alum to the solution to harden and preserve the gelatin.

How to Use: Keep the solution warm while you use it but never overheat or warm it over direct heat. Make a paste of dry pigment and water, and thoroughly mix this paste with a palette knife into the warm gelatin solution on a glass plate. Use bristle brushes and paint directly onto gesso panels in thin layers.

Dammar Varnish

Dammar resin—either Batavia or Singapore—is available in pale yellow lumps, and serves many purposes: medium, glaze and final varnish.

How To Prepare: Place the resin lumps and turpentine in a tightly capped bottle, agitate daily until the resin has dissolved, which may require a few days. If the dammar lumps contain impurities, strain through cheesecloth into a clean bottle.

How to Use: To use as a final varnish on a painting, dilute the solution with four times as much turpentine. This recipe is best for use in emulsifying or combining with other ingredients to make mediums. This dammar solution dries in about one hour.

Preparation of Pigments for Tempera

Pigments intended for use in tempera and emulsion paints are best acquired in the form of a finely divided, dry powder. However, natural mineral pigments, such as cinnabar, azurite and malachite, are better to use in relatively coarsely ground form. To ensure a smooth paint, grind the dry pigment in water into a stiff paste and store it in this form prior to adding the pigment to paint, unless otherwise directed in the recipe. The proportion of pigment to paint binder will vary greatly for each pigment and binder. Thus, for example, the same quantity of whiting may require only one part of gum emulsion but two parts of casein emulsion.

Paints that you intend to cover with a varnish or olifa (oil varnish) should have a higher proportion of pigment to binder, then paintings you do not plan to varnish. It is better not to mix enough binder with pigment than too much binder. A deficiency in binder can easily be corrected by impregnating the dried paint surface using the same emulsion diluted with water and applied with a soft brush.

When preparing pigments for mat paint films, dark-toned colors work best with emulsions containing a higher oil content. However, light-toned pigments should be used with emulsions having a smaller content of oil.

During long storage, pigments sometimes lose their ability to become properly “wetted” and are more difficult to mix with water. In this case, you can add a small amount of ethyl alcohol, isopropyl alcohol or oxgall to the grinding slab when mixing with water.

Here are a few observations about the use of certain pigments in tempera and tempera-emulsions:

Cadmium Red, Madder Lake, and Naples Yellow Do not allow these pigments to come in contact with metal. Always grind these pigments with a ceramic, stone or glass pestle, and use plastic knives when mixing on a palette.

Chrome Red and Chrome Yellow, a brick-red crystalline powder, is basic lead chromate and can be successfully used in tempera, but does not withstand too fine grinding from which it acquires a yellow nuance. It is not widely used because it lacks brilliancy and is readily affected by sulfur gasses.

Cinnabar is a bright red, natural mineral pigment, consisting of mercury sulfide. It was widely used in Russian icon painting since the 12th century and in oil painting since the 18th century. It is successfully used in tempera and oil painting and is quite permanent.

Hematite is a dark, cherry-red natural mineral with some types having a yellowish-red or brownish-red nuance. It consists of ferric oxide with clay and quartz, possesses excellent covering power, and is impervious to alkalis and weak acids. It has been used since ancient times and is successfully employed in all painting techniques.

Lead White or flake white in egg tempera can yellow and with the drying of the egg emulsion may acquire a dirty nuance as a result of contamination with hydrogen sulfide that may be present in putrefied egg emulsions.

Minium (See Red Lead)

Prussian Blue is very sensitive to alkalis, such as ammonia used in casein tempera, which causes it to turn brown, especially if stored for long periods as a prepared pigment.

Red Lead, minium or orange mineral is red tetroxide of lead made by heating litharge or white lead for some hours at a temperature above 480º C. In Russian icon painting, it was frequently substituted for more costly cinnabar (See Cinnabar).

Surik is a name widely-used in Russia for almost any reddish-brown pigment. The name usually applies to minium (see Red Lead). It is good for scumbling over glazes of madder lake. With the drying of egg lipids it acquires a darker nuance. Surik Jeleznii is another Russian name for hematite or red ochre, which consists of iron oxide and natural impurities, such as clay and quartz (See Hematite).

Ultramarine is sensitive to weak acids and suffers from the presence of strong vinegar, being decomposed by it and liberating hydrogen sulfide in the process.

Umber requires a large amount of emulsion to form a paste and slows the drying time, so that it can be dissolved by water for some time afterwards. It also frequently separates from the binder and decomposes in casein emulsions. To avoid this a small amount of ammonium hydroxide can be added to the pigment when grinding it with the binder.

Vermilion (See Cinnabar)

Zinc White or zinc oxide (like lead white) is sensitive to acids, such as vinegar. Zinc white has considerably better covering power in tempera than in oil paint.