Tempera medium

Casein is an insoluble protein found in milk. It is used to make adhesives and fillers, water-resistant coatings, and as an additive in some plastics and commercial food products like non-dairy creamers and soy cheese. The milk from cows, sheep, and goats has been used, alone or mixed with fillers, as gesso or as a tempera medium. Casein mixed with fillers such as sawdust or plant materials has been molded into various objects, such as buttons, knitting needles, button hooks, and jewelry. It has been used as an imitation of ivory under the commercial names erinoid and galalith. 

The use of the various tempera and of wax has been identified on objects dating back to ancient Egypt. The Eayum mummy portraits are beautiful examples of encaustic painting, ie, using molten wax as medium. A rather special variation was the technique used by the Romans for wall paintings. In these, the medium, referred to by Pliny as Punic wax, probably consisted of partially saponified wax. In Europe, wax ceased to be used by the ninth century. 

The earhest written references to the use of oils as paint media date from the twelfth century. The van Eycks, who traditionally have been credited as the inventors of oil painting, improved the technique to such a degree that oil quickly replaced egg tempera as the prevalent medium. 

Each painter had his own technique the binding medium was thus prepared using different additives, giving rise to a variety of recipes for each technique. For example, it is believed that fig latex (a white liquid exuded by the fig tree) was commonly added to the egg tempera, and that animal or plant resins were added to oil- and wax-based binders. On account of their adhesive properties, these materials were used not only as paint binders, but also as consolidants in restorations, as ingredients in varnishes used to finish paintings, and as ingredients of mordants to apply metallic leaf decorations. 

Its higher velocity 2) The finite pressure difference in the wave front 3) The increase in temperature and density of the medium thru the wave and 4) Physical flow of the material in the direction of advance of the wave. The rate of this flow, as well as that of wave propagation, and the magnitudes of the increases in density, tempera-... 

It can be seen that, historically, a paint is anything that contains pigment, a colored, powdered substance, and a binder, a material that evenly disperses the pigment and adheres to a surface when the paint is applied and then dries. A pigment combined with a binder makes a paint. A medium is used to dilute a paint. The composition of watercolor, egg tempera, oil, and acrylic paints is discussed in this chapter. 

Each artist has a favorite medium that best fits his or her needs. Following is a short description of various paint media—watercolor, egg tempera paint, oil paint, and acrylic paint—and their advantages and disadvantages. A discussion of poster paint (or tempera paint), suitable for school use, is also included. 

Egg tempera was used as a paint medium at least as early as the fourteenth century. It was the dominant medium in Europe until the development of oil paint. In egg tempera, powdered pigment is bound with egg and water. Paint is applied layer upon layer, imparting a luminous quality unlike any other paint medium. The advantages and disadvantages of egg tempera are about equal ... 

The thermal efficiency of a steam power cycle is increased when the press and hence the vaporization temperature in the boiler is raised. It is also increas by increased superheating in the boiler. Thus, high boiler pressures and te peratures favor high efficiencies. However, these same conditions increase capital investment in the plant, because they require heavier construction more expensive materials of construction. Moreover, these costs increase ev more rapidly as more severe conditions are imposed. Thus, in practice po plants seldom operate at pressures much above 10,000 kPa and tempera much above 600°C. The thermal efficiency of a power plant increases as pressure and hence the temperature in the condenser is reduced. However, condensation temperature must be higher than the temperature of the coo medium, usually water, and this is controlled by local conditions of climate geography. Power plants universally operate with the condenser pressure as 1 as practicable. 

Although the pigment was not successfully identified in this case, the information that egg tempera is present as the binding medium is a valuable characterization by itself. Egg yolk was also identified in spectra obtained from a different-colored pigment sample from the same manuscript. 

The use of an acylating medium for effecting scission of the acetal ring of a cyclic acetal of a sugar was first demonstrated in the conversion of methyl 4,6-0-ethylidene- 3-D-glucoside into methyl 4-0-(l-acetoxyethyl)-6-0-acetyl- 3-D-glucoside. The reagent employed was a 0.1% (vol./vol.) solution of concentrated sulfuric acid in acetic anhydride at room tempera-... 

Gravity vessels are suitable for low-, medium-, and high-tempera-ture operation in the last case, the housing will be lined completely with refractory brick. Dust recovery equipment is minimized in this type of operation since the bed actually performs as a dust collector itself, and dust in the bed will not, in a successful application, exist in large quantities. 

Diffusing component 2" Mixture component (diffusion medium) (solvent) Pressure (bar) Tempera- ture ( C) Concentration (%) Diffusion coefficient (m /h)... 

A great number of the measurements on permeability have been made upon the complex membranes of Table 112, in which the chemical nature of the membranes is briefly indicated. Most of the membranes sorb water freely. Natural rubber, one of the least hydrophilic of these substances, may if exposed to water vary from a non-swelling non-sorbing medium to complete dispersion in the water, according to the carbohydrate and protein content (3). Nearly all cellulose or protein-containing substances swell and sorb water strongly (4), and the accompanying sorption is then influenced by tempera-... 

Vacuum operation is expensive and is recommended only if the product must be dried at low temperatures or in the absence of oxygen or has flavors that are generated at medium- or high-tempera-ture operation. High-temperature operation tends to be more efficient since lower gas flow rates and smaller equipment may be used for a given evaporation duty. Availability of low-temperature waste heat or energy from solar collectors may dictate the choice of a lower temperature operation. These dryers will then be large in size. 

Casein paints were very popular in early 1960s until the introduction of acryhc paint It is a fast-drying, water-soluble medium used by artists and has been used since ancient Egyptian times as a form of tempera paint. 

Porohyridium cruentum 13.80 Culture Collection. Cultures wer <80x5 cm) incubated in a tempera (unless otherwise stated) with f 170 pE m 2 g-l at side of th ail CO2 mixture (95 5) through a each culture tube. For the nitr exponential phase of growth (28 in a nitrogen-free medium. The c under the same light and tempera... 

---