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Ra (Japanese textile)

Ra (Japanese textile) is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Ra (Japanese textile) rather than just read about it. In short: Ra (羅; also read usumono, 'sheer fabric') is a lightweight, translucent textile found in the history of Japanese weaving. It is generally made of silk and woven in a form of openwork leno weave, in which warp threads cross adjacent warp threads and are held in place by the weft.

Key takeaways

  • Ra (Japanese textile) belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Ra (Japanese textile) to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Ra (Japanese textile) from memory before moving on to harder problems.

Reference excerpt

Ra (羅; also read usumono, 'sheer fabric') is a lightweight, translucent textile found in the history of Japanese weaving. It is generally made of silk and woven in a form of openwork leno weave, in which warp threads cross adjacent warp threads and are held in place by the weft. The resulting fabric has an open, net-like structure. Ra in which patterns are formed as part of the weave is called mon-ra (文羅, also written 紋羅), while ra without woven patterns is called mumon-ra (無文羅). Historically, the term ra was used in both a broad and a narrow sense. In its broad sense, it referred generally to lightweight, sheer silk fabrics, including sha (紗), a relatively simple gauze weave, and ro (絽), which combines sections of plain weave with regularly spaced leno-weave openings. In its narrower sense, ra denoted a particular group of complex gauze structures made by interlacing warp threads in more elaborate arrangements. Consequently, textiles described by the character 羅 in Chinese or Korean texts, or archaeological finds classified by that term, do not necessarily have the same fiber material, weave structure, or production technique as Japanese ra. Comparable openwork weaves have also been found in regions such as South America, but they were not locally known as ra; rather, the term has been applied to them within Japanese systems of textile classification. This article focuses primarily on ra in the history of Japanese textiles.

Terminology and definition The Sino-Japanese term ra derives from the Chinese character 羅, which originally denoted a net used to catch birds. The term was subsequently applied to sheer textiles resembling nets and came to be used more broadly for lightweight or high-quality silk fabrics. In Japanese, the character is read ra or usumono, the latter meaning 'sheer fabric'. In its broad sense, ra was a general term for loosely woven, lightweight fabrics, including sha (紗) and ro (絽). In its narrower sense, it refers to a weave structure in which parallel warp threads alternately cross adjacent warp threads, with the crossings held in place by the weft. In this narrower sense, ra is distinguished from sha and ro, which also belong to the family of Japanese leno or gauze weaves, by the way in which the warp threads are manipulated. In sha, two warp threads form a pair and cross around the weft, producing a relatively simple gauze structure. In ro, sections of plain weave alternate at regular intervals with crossings of two warp threads. Varieties are distinguished according to the number of weft picks in each plain-weave section, including three-pick ro (三越絽) and five-pick ro (五越絽). In ra, by contrast, warp threads cross multiple adjacent warp threads, producing open meshwork or geometric patterns. The distinction cannot, however, be reduced to the simple rule that sha uses two warp threads whereas ra uses three or more. In the traditional classification of yūsoku textiles—fabrics used for Japanese court costume—a special heddle device called a furue (振綜) was used to manipulate two or four warp threads and produce the geometric patterns of ra. At the same time, a structure using three manipulated warp threads that became widespread during the medieval period was regarded as a type of ra but was also known as kenmon-sha (顕紋紗). The historical terms ra, sha, and ro must therefore be understood as classifications involving not only the number of warp threads but also their movement, the manner in which they cross, and the way woven patterns are formed. Terminology and classification also differ between regions. In the traditional textile classification of the Korean Peninsula, structures in which groups of three or four warp threads cross one another are classified as na (나; 羅, also pronounced ra in Korean), while structures using pairs of warp threads are classified as sa (사; 紗). By contrast, hangra (항라; 亢羅), despite containing the character 羅 in its name, is classified as a ro weave. It alternates sections of plain weave with regularly spaced crossings of two warp threads and is not classified as a ra structure. The presence of the character 羅 in a textile's name therefore does not, by itself, indicate that it has the same structure as Japanese ra. Patterned ra, known as mon-ra (文羅 or 紋羅), is produced by varying the way in which the warp threads cross so that the pattern forms as an integral part of the weave. It is therefore distinct from plain ra to which a pattern has subsequently been added by dyeing or embroidery. Ra without woven patterns is called mumon-ra (無文羅). The Shōsō-in repository preserves examples of mon-ra woven with diamond-shaped, lattice-like, and other geometric patterns.

History in Japan

Ancient period When and by what route the technique of weaving ra reached Japan remains uncertain. Whether individual early examples were imported from continental East Asia or woven locally in Japan must therefore be considered separately for each surviving textile. The surviving fragments of the Tenjukoku Shūchō Mandala, traditionally said to have been commissioned in 622—the thirtieth year of the reign of Empress Suiko—following the death of Prince Shōtoku, include purple ra used as a base fabric for embroidery. The extant work incorporates both early fragments and sections added when the embroidery was reproduced during the Kamakura period (1185–1333), but the purple ra section remains an important early example of both ra and embroidery preserved in Japan. The production of ra flourished during the Nara period (710–794). It was woven in various parts of Japan and used for court dress and other forms of attire. The Shōsō-in, an eighth-century imperial repository in Nara, preserves numerous examples. Its finely woven mon-ra, featuring intricate patterns formed as part of the weave, demonstrates the advanced level attained by Japanese weaving techniques during this period. The Shōsō-in textiles include patterned ra, dyed ra, and belts made from the fabric. Some belts were embroidered over a ground of ra, showing that the textile was used not only as a lightweight, sheer fabric but also as a decorative ground in combination with dyeing and embroidery.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Ra (Japanese textile)

Start with the simplest possible case. Write down what Ra (Japanese textile) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Ra (Japanese textile) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Ra (Japanese textile) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Ra (Japanese textile)

In research
Ra (Japanese textile) appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Ra (Japanese textile) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Ra (Japanese textile) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Japanese weaving techniques, Silk, Woven fabrics, so understanding it makes those chapters shorter.
In everyday life
Look for Ra (Japanese textile) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Ra (Japanese textile) in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Ra (Japanese textile) means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Ra (Japanese textile) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ra (Japanese textile) in simple terms?

Ra (羅; also read usumono, 'sheer fabric') is a lightweight, translucent textile found in the history of Japanese weaving. It is generally made of silk and woven in a form of openwork leno weave, in which warp threads cross adjacent warp threads and are held in place by the weft.

Why does Ra (Japanese textile) matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Ra (Japanese textile)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Ra (Japanese textile).

Tags

  • Japanese weaving techniques
  • Silk
  • Woven fabrics

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