Letter cutting is a form of inscriptional architectural lettering related to monumental masonry and stone carving practiced by artists and typeface designers. Rather than traditional stone carving, where images and symbols are the dominant features, in letter cutting it is the beauty of the stone carver's calligraphy, the focus. Notable practitioners include: Eric Gill, Ralph Beyer David Kindersley Richard Kindersley John Shaw
Thermoset polymer matrix
A thermoset polymer matrix is a synthetic polymer reinforcement first developed for structural applications, such as glass-reinforced plastic radar domes on aircraft and graphite-epoxy payload bay doors on the space shuttle. In polymer matrix composites, polymers act as binder or matrix to secure in place incorporated particulates, fibres or other reinforcements, they were first used after World War II, continuing research has led to an increased range of thermoset resins, polymers or plastics, as well as engineering grade thermoplastics, all developed for use in the manufacture of polymer composites with enhanced and longer-term service capabilities. Thermoset polymer matrix technologies find use in a wide diversity of non-structural industrial applications; the foremost types of thermosetting polymers used in structural composites are benzoxazine resins, bis-Maleimide resins, cyanate ester resins, epoxy resins, phenolic resins, unsaturated polyester resins, polyurethane resins and vinyl esters.
These are made by the reaction of phenols and primary amines which at elevated temperatures undergo ring–opening polymerisation forming polybenzoxazine thermoset networks. Cure is characterised by expansion rather than shrinkage and uses include structural prepregs, liquid molding and film adhesives for composite construction and repair; the high aromatic content of the high molecular weight polymers provides enhanced mechanical and flammability performance compared to epoxy and phenolic resins. Formed by the condensation reaction of a diamine with maleic anhydride, processed like epoxy resins. After an elevated post-cure, they will exhibit superior properties; these properties are influenced by a 400-450 °F continuous use temperature and a glass transition of 500 °F. This thermoset polymer type is merged into composites as a prepreg matrix used in electrical printed circuit boards, for large scale structural aircraft – aerospace composite structures, etc, it is used as a coating material and as the matrix of glass reinforced pipes in high temperature and chemical environments.
The reaction of bisphenols or multifunctional phenol novolac resins with cyanogen bromide or chloride leads to cyanate functional monomers which can be converted in a controlled manner into cyanate ester functional prepolymer resins by chain extension or copolymerization. When postcured, all residual cyanate ester functionality polymerises by cyclotrimerisation leading to crosslinked polycyanurate networks with high thermal stability and glass transition temperatures up to 752 °F and wet heat stability up to around 400 °F. Cyanate ester resin prepregs combine the high temperature stability of polyimides with the flame and fire resistance of phenolics and are used in the manufacture of aerospace structural composite components which meet fire protection regulations concerning flammability, smoke density and toxicity. Other uses include surfacing films and 3D printing. Epoxy resins are thermosetting prepolymers made either by the reaction of epichlorohydrin with hydroxyl functional aromatics and aliphatics or amine functional aromatics, or by the oxidation of unsaturated cycloaliphatics.
The diglycidyl ethers of bisphenol-A and bisphenol-F are the most used due to their characteristic high adhesion, mechanical strength and corrosion resistance. Epoxide functional resins and prepolymers cure by polyaddition/copolymerisation or homopolymerisation depending on the selection of crosslinker, curing agent or catalyst as well as by the temperature. Epoxy resin is used in numerous formulations and forms in the aircraft-aerospace industry, it is regarded as "the work-horse of modern day composites". In recent years, the epoxy formulations used in composite prepregs have been fine-tuned to improve their toughness, impact strength and moisture absorption resistance. Maximum properties have been realized for this polymer; this is not only used in aircraft-aerospace demand. It is used in military and commercial applications and is used in construction. Epoxy-reinforced concrete and glass-reinforced and carbon-reinforced epoxy structures are used in building and bridge structures. Epoxy composites have the following properties: High-Strength Glass Fiber Reinforced Relative Density 1.6-2.0 Melting temperature Thermoset Processing Range C:300-330,I=280-380 Molding pressure 1-5 Shrinkage 0.001-0.008 Tensile strength 5,000-20,000 Compressive strength 18,000-40,000 Flexural Strength 8000-30,000 Izod impact strength 0.3-10.0 Linear expansion 11-50 Hardness Rockwell M100-112 Flammability V-0 Water absorption 24h 0.04-0.20 Epoxy Phenol Novolac and Epoxy Cresol Novolac resins made by reacting epichlorohydrin with multifunctional phenol novolac or cresol novolac resins have more reactive sites compared to DGEBF epoxy resins and on cure result in higher crosslink density thermosets.
They are used in printed wire/circuit board laminating and for electrical encapsulation and coatings for metal where there is a need to provide protection from corrosion, erosion or chemical attack at high continuous operating temperatures. There are two types of phenolic resins - resoles. Novolacs are made with acid catalysts and a molar ratio of formaldehyde to phenol of less than one to give methylene linked phenolic oligomers.
Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English "plaster" means a material used for the interiors of buildings, while "render" refers to external applications. Another imprecise term used for the material is stucco, often used for plasterwork, worked in some way to produce relief decoration, rather than flat surfaces; the most common types of plaster contain either gypsum, lime, or cement, but all work in a similar way. The plaster is manufactured as a dry powder and is mixed with water to form a stiff but workable paste before it is applied to the surface; the reaction with water liberates heat through crystallization and the hydrated plaster hardens. Plaster can be easily worked with metal tools or sandpaper, can be moulded, either on site or to make pre-formed sections in advance, which are put in place with adhesive. Plaster is not a strong material. Forms of plaster have several other uses.
In medicine plaster orthopedic casts are still used for supporting set broken bones. In dentistry plaster is used to make dental impressions. Various types of models and moulds are made with plaster. In art, lime plaster is the traditional matrix for fresco painting. In the ancient world, as well as the sort of ornamental designs in plaster relief that are still used, plaster was widely used to create large figurative reliefs for walls, though few of these have survived. Clay plaster is a mixture of clay and water with the addition of plant fibers for tensile strength over wood lath. Clay plaster has been used since antiquity. Settlers in the American colonies used clay plaster on the interiors of their houses: “Interior plastering in the form of clay antedated the building of houses of frame, must have been visible in the inside of wattle filling in those earliest frame houses in which …wainscot had not been indulged. Clay continued in the use long after the adoption of laths and brick filling for the frame."
Where lime was not available or accessible it was rationed or substituted with other binders. In Martin E. Weaver’s seminal work he says, “Mud plaster consists of clay or earth, mixed with water to give a “plastic” or workable consistency. If the clay mixture is too plastic it will shrink and distort on drying, it will probably drop off the wall. Sand and fine gravels were added to reduce the concentrations of fine clay particles which were the cause of the excessive shrinkage.” Straw or grass was added sometimes with the addition of manure. In the Earliest European settlers’ plasterwork, a mud plaster was used or more a mud-lime mixture. McKee writes, of a circa 1675 Massachusetts contract that specified the plasterer, “Is to lath and siele the four rooms of the house betwixt the joists overhead with a coat of lime and haire upon the clay. 5. To lath and plaster partitions of the house with clay and lime, to fill and plaister them with lime and haire besides. 6. The said Daniel Andrews is to find lime, clay, haire, together with laborers and workmen….”
Records of the New Haven colony in 1641 mention hay as well as lime and hair also. In German houses of Pennsylvania the use of clay persisted.” Old Economy Village is one such German settlement. The early Nineteenth-Century utopian village in present-day Ambridge, used clay plaster substrate in the brick and wood frame high architecture of the Feast Hall, Great House and other large and commercial structures as well as in the brick and log dwellings of the society members; the use of clay in plaster and in laying brickwork appears to have been a common practice at that time not just in the construction of Economy village when the settlement was founded in 1824. Specifications for the construction of, “Lock keepers houses on the Chesapeake and Ohio Canal, written about 1828, require stone walls to be laid with clay mortar, excepting 3 inches on the outside of the walls…which to be good lime mortar and well pointed.” The choice of clay was because of its low cost, but the availability. At Economy, root cellars dug under the houses yielded clay and sand, or the nearby Ohio river yielded washed sand from the sand bars.
Other required building materials were sourced locally. The surrounding forests of the new village of Economy provided straight grain, old-growth oak trees for lath. Hand split lath starts with a log of straight grained wood of the required length; the log is spit into quarters and smaller and smaller bolts with wedges and a sledge. When small enough, a froe and mallet were used to split away narrow strips of lath - unattainable with field trees and their many limbs. Farm animals pastured in the fields cleared of trees provided the hair and manure for the float coat of plaster. Fields of wheat and grains provided straw and other grasses for binders for the clay plaster, but there was no uniformity in clay plaster recipes. Straw or grass was added sometimes with the addition of manure providing fiber for tensile strength as well as protein adhesive. Proteins in the manure act as binders; the hydrogen bonds of p
A tessera is an individual tile formed in the shape of a cube, used in creating a mosaic. It is known as an abaciscus or abaculus; the oldest known tesserae dates to the 3rd millennium BCE, discovered in the ancient city of Shahdad in Kerman province, Iran. In early antiquity, mosaics were formed from formed colored pebbles. By 200 BCE cut stone tesserae were being used in Hellenistic-Greek mosaics. For instance, a large body of surviving material from the Hellenistic period can be found in the mosaics of Delos, dating to the late 2nd century BCE. Ancient Roman decorative mosaic panels and floor mosaics were produced during the 2nd century BC at sites such as Pompeii. Marble or limestone were cut into small cubes and arranged into representational designs and geometric patterns. Tesserae were made from colored glass, or clear glass backed with metal foils; the Byzantines used tesserae with gold leaf, in which case the glass pieces were flatter, with two glass pieces sandwiching the gold. This produced a golden reflection emanating from in between the tesserae as well as their front, causing a far richer and more luminous effect than plain gold leaf would create.
Vitreous glass These are manufactured glass tiles made to size. They are made by molten glass being fired. An imprint of grooves is made on their underside for help with adhesion to cement. Ceramic tesserae These are the cheapest range of can be glazed or unglazed; the glazed ceramic tiles have the color painted onto the top of the clay and fired to a high temperature in a kiln. The unglazed or body glazed version has the color mixed into the wet clay so the color runs through them, they vary in size. Smalti This is the classic mosaic material, it is opaque glass fired in large slabs in a kiln and hand cut with a hammer and hardy chisel into small cubes. Their irregular finish makes them a wonderful reflector of light and this material is best used working straight into cement, it is sold by colour and weight. Gold smalti This tile is made with real gold and silver leaf sandwiched between two layers of glass and fired twice in the kiln to embed in the metal. Mirror Mirror adds great sparkle to a mosaic.
It is cheap as offcuts from a glass cutting shop are free. Use mirror glue. Stained glass Known for its translucent qualities stained glass is available in opaque form, it comes as large sheets. It can provide areas of larger tesserae pieces for contrast. Household ceramic tiles & china Colours and surfaces are limitless and can add texture and contrast to mosaic work in the technique known as trencadís or pique assiette. Tessellation — describes tessellation patterns Mosaic — describes techniques for assembling tesserae into a design
Slipform stone masonry is a method for making a reinforced concrete wall with stone facing in which stones and mortar are built up in courses within reusable slipforms. It is a cross between a veneered stone wall. Short forms, up to 60 cm high, are placed on both sides of the wall to serve as a guide for the stone work; the stones are placed inside the forms with the good faces against the form work. Concrete is poured in behind the rocks. Rebar is added for strength, to make a wall, half reinforced concrete and half stonework; the wall can be faced with stone on both sides. After the concrete sets enough to hold the wall together, the forms are “slipped’ up to pour the next level. With slipforms it is easy for a novice to build free-standing stone walls. Slipform stone masonry was developed by New York architect Ernest Flagg in 1920. Flagg built a vertical framework as tall as the wall inserted 2x6 or 2x8 planks as forms to guide the stonework; when the masonry work reached the top of a plank, Flagg inserted another one, adding more planks until he reached the top of the wall.
Helen and Scott Nearing modified the technique in Vermont in the 1930s, using slipforms that were slipped up the wall. The diagram of the slipform wall section is misleading without showing the 2nd form. Slipform Stone Masonry
In classical architecture rustication is a range of masonry techniques giving visible surfaces a finish that contrasts in texture with the smoothly finished, squared-block masonry surfaces called ashlar. The visible face of each individual block is cut back around the edges to make its size and placing clear. In addition the central part of the face of each block may be given a deliberately rough or patterned surface. Rusticated masonry is "dressed", or squared off neatly, on all sides of the stones except the face that will be visible when the stone is put in place; this is given wide joints that emphasize the edges of each block, by angling the edges, or dropping them back a little. The main part of the exposed face may be worked flat and smooth or left with, or worked, to give a more or less rough or patterned surface. Rustication is used to give visual weight to the ground floor in contrast to smooth ashlar above. Though intended to convey a "rustic" simplicity, the finish is artificial, the faces of the stones carefully worked to achieve an appearance of a coarse finish.
Rustication was used in ancient times, but became popular in the revived classical styles of Italian Renaissance architecture and that of subsequent periods, above all in the lower floors of secular buildings. It remains in use in some modern architecture. Similar finishes are common in medieval architecture in castles and similar buildings, but here it arises from an unwillingness to spend the extra money required for ashlar masonry in a particular building, lacks the deliberate emphasis on the joints between blocks. Though it achieves a decorative effect, this is something of a by-product, the exploitation for architectural effect within a single building of contrasts between rusticated and ashlar surfaces is seen. In some buildings, such as the Palazzo Vecchio in Florence something other than cost-saving is at play, this may be the association of the technique with the display of power and strength, from its use in military architecture. Rough finishes on stone are very common in architecture outside the European tradition, but these too would not be called rustication.
For example, the bases of Japanese castles and other fortifications use rough stone very attractively. Although rustication is known from a few buildings of Greek and Roman antiquity, for example Rome's Porta Maggiore, the method first became popular during the Renaissance, when the stone work of lower floors and sometimes entire facades of buildings were finished in this manner, it was used for secular buildings, has always remained uncommon in churches through a lingering association with the architecture of military power. The earliest and most influential example is the Palazzo Medici Riccardi in Florence, built between 1444 and 1484, with two contrasting rusticated finishes; the ground floor has an irregular and genuinely rugged appearance, with a variation in the degree to which parts of the faces of blocks project from the wall, equalled later. Above, the rustication is to emphasize the individual blocks, the faces are all smooth and even. In Florence, Palazzo Strozzi, begun 1489, with large oblong rounded cushions, the front of the Pitti Palace, begun 1458, rusticated their whole facades in the same style.
These facades only used the classical orders in mullions and aedicules, with arched forms in rustication the main relief from the massive flat walls. The Palazzo Rucellai of the 1460s, begins to classicize such facades, using smooth-faced rustication throughout, except for the pilasters at each level. In Rome, Donato Bramante's Palazzo Caprini provided a standard model for the integration of rustication with the orders. Here the obvious strength of a blind arched arcade with emphatic voussoirs on the rusticated ground storey gave reassuring support to the upper storey's paired Doric columns standing on rusticated piers, set against a smooth wall; the first major Renaissance building in Spain, the Palace of Charles V in Granada, had a rusticated ground floor facade with regular rounded cushions. The technique was enthusiatically taken up by the next generation of Mannerist architects, with Giulio Romano in the lead. Most early examples of this "rustic" style are therefore built for sophisticated patrons in the leading centres of taste.
Giulio's Palazzo Stati Maccarani in Rome and Palazzo Te in Mantua expand the voussoirs still further, the courtyard in Mantua plays games with the technique, with some blocks ashlar, other projecting further than the rest, larger blocks placed higher than smaller ones. The Mannerist architectural writer Sebastiano Serlio and others of his generation enjoyed the play between rusticated and finished architectural elements. In the woodcut of a doorway from Serlio's 1537 treatise, the banded rustication of the wall is carried right across the attached column and the moldings of the doorway surround, binding together all the elements; the Italians brought in to expand the Palace of Fontainebleau introduced the technique to France. Its spread to Germany and England took longer, but by about the end of the 16th century it had reached all parts of Europe. In his Banqueting House in London, Inigo Jones gave a rusticated surface texture to emphasize the blocks on both storeys, to unify them behind his orders of pilasters and columns.
During the 18th century, following the Palladian revival, rustication was used on the ground floors of large buildings, as its contrived appea
Rubble masonry is rough, unhewn building stone set in mortar, but not laid in regular courses. It may appear as the outer surface of a wall or may fill the core of a wall, faced with unit masonry such as brick or cut stone. Snecked masonry - Masonry made of mixed sizes of stone but in regular courses