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Mottle
Mottle
Mottle
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This Appaloosa horse shows mottling around its mouth and nostrils. In this particular case, it is a normal hereditary trait linked to a spotted coat color-pattern and not a sign of disease.
Look up mottle in Wiktionary, the free dictionary.

A mottle is a pattern of irregular marks, spots, streaks, blotches or patches of different shades or colours. The term commonly describes the surface of plants or the skin of animals. In plants, mottling usually consists of yellowish spots on plants, and is usually a sign of disease or malnutrition.[1] Many plant viruses cause mottling, for example:

"Mottling" is sometimes used to describe uneven, discolored patches on the skin of humans as a result of cutaneous ischemia (lowered blood-flow to the surfaces of the skin) or Herpes zoster infections.[2] The medical term for mottled skin is dyschromia.[3] Although not always the case, mottling can occur in a dying patient and commonly indicates that the end of life is near. Mottling usually occurs in the extremities (lower first) and progresses up as cardiac function declines and circulation throughout the body is poor.[3] In animals, mottling may be a sign of disease, but may also be a hereditary trait, as seen with the champagne and leopard complex genes in horses.

"Mottles" can also refer to discoloration in processed food, such as butter.[4]

In geology, "mottled" refers to a patchy/blotch texture of alteration or interbedding, commonly found in limestone and commonly caused by bioturbation.[5]

"Mottling" can also refer to an undesirable defect which can occur with effect coatings, most obvious on light metallic finishes. The total color impression shows irregular areas of lightness variations. These "patches" are usually visually evaluated, described as a mottling effect. Some also feel that it reminds them of clouds.[citation needed] This effect is especially noticeable on large body panels. It can be caused by the coating formulation, as well as by variations in the application process. For example, disorientation of the metallic flakes or film thickness variations of the basecoat can lead to various mottle sizes resulting in a non-uniform appearance. The visual perception of mottling is dependent on the viewing distance: Large mottles can be seen in far-distance evaluation, while small mottles are more noticeable in close-up evaluation. The visual evaluation of mottling is very subjective, and depends on the illumination conditions, the observing distance and the viewing angle.

In graphics printing, "mottling" refers to an uneven coloration resulting from letterpressed printing of textured papers, mainly in larger colored surfaces. Due to the uneven surface, not all fibers of the paper are evenly saturated with color — unlike in offset printing.

Measurement

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The irregular lightness variations caused by mottling can be objectively measured with specially made instruments. These instruments simulate visual evaluation under different observing angles and characterize clouds / mottles by their size and visibility.[6] Small to large mottles are measured under three observing angles, in which the scan length can usually be varied from 10 to 100 cm. The measurement results are independent of color and curvature of the surface and thus can be considered objective.[7]

The specific measurement process for one such instrument is as follows. It first optically scans the surface and measures the lightness variations. The specimen is illuminated with a white light LeD at a 15° angle and the lightness is detected under three viewing angles to simulate visual evaluation under different observing conditions: 15°, 45° and 60° measured from the specular reflection. The mottling meter is rolled across the surface for a defined distance of 10 to 100 cm and measures the lightness variations point by point. The measurement signal is divided via mathematical filter functions into 6 different size ranges and a rating value is calculated for each angle and mottle size. The higher the value is, the more visible the mottling effect. The measured values are displayed in a graph showing the mottle size on the X-axis and the rating value on the Y-axis. Thus, target values for small and large mottle sizes can be established for paint batch approval as well as process control.[8]

Military

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Flecktarn mottle camouflage

Military battledress often use a mottle pattern, such as Frog Skin and Flecktarn.

References

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Mottle

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from Grokipedia
Mottle (Chinese: 斑驳; pinyin: bān bó) is a term denoting a of irregular spots, blotches, streaks, or patches of contrasting colors or shades, often observed in natural materials such as leaves and soils. In , mottle describes a common symptom of viral infections, where leaves exhibit an irregular of light green, , or chlorotic areas interspersed with darker green regions, potentially leading to , malformation, or reduced yield in affected crops. For instance, viruses like cherry mottle leaf cause puckered leaves with blotches on cherries, while pod mottle produces green-to- mottling on foliage, sometimes accompanied by pod distortion. Such symptoms can also arise from nutrient deficiencies, such as shortage leading to mottle-leaf in , characterized by partial and smaller leaves. In , mottles are secondary color features within the matrix, appearing as spots or blotches of colors like orange, red, gray, or blue that differ from the dominant soil hue, serving as visual indicators of soil and status. These features typically form due to periodic saturation, which depletes oxygen and promotes iron reduction or oxidation, with gray mottles (>50% abundance) signaling poor drainage and compaction risks, while fewer orange mottles suggest moderate conditions. mottling is assessed through field pits or auger samples to inform , such as avoiding compaction-prone areas for .

Definition and Overview

Definition

A mottle is a pattern of irregular marks, spots, streaks, blotches, or patches of different shades or colors on a surface. The equivalent term in Chinese is 斑驳 (pinyin: bān bó), which similarly denotes a state of mixed, irregular, and uneven color patterns. This visual effect arises from variations in pigmentation, texture, or composition, creating a non-uniform appearance that contrasts with smooth or even surfaces. Key characteristics of a mottle include its irregularity in distribution, where elements do not follow a predictable grid or , and the presence of contrast between adjacent shades, which can range from subtle gradations to stark differences. The scale varies widely, from microscopic flecks observable only under to large patches spanning entire surfaces, often resulting in visual impacts such as blending into surroundings or disrupting perceived uniformity. Mottles appear in diverse general contexts, such as the dappled patterns on leaves, the variegated discolorations on , the streaked formations in rocks like , or the intentional spotting on manufactured items like textiles. The term originated in the early .

Etymology

The term "mottle" emerged in English as a in the early 17th century, denoting the action of spotting or streaking with irregular patches of color. Its earliest recorded use dates to 1602, appearing in the writings of poet and anthologist Francis Davison. This form arose through clipping or shortening from the verb "," which itself originated in the period around 1447 and meant to diversify with colors. The root "," an and noun from the late 14th century, described something parti-colored or variegated, likely deriving from Old English "mot" () or Anglo-Norman "motteley," evoking a of hues akin to a fool's multicolored garb. By the late 17th century, "mottle" had developed into an adjective, with its first attestation in 1676 in the London Gazette, where it characterized surfaces marked by blended spots or blotches. As a noun, referring to a pattern of such marks, it appeared around the same period, often as a back-formation from "motley." Related terms include the parent word "motley," denoting diversity in color; synonyms such as dapple, fleck, and stipple, which similarly imply speckled or dotted effects; and antonyms like uniform or solid, suggesting evenness without variation. The word's usage timeline reflects early literary influences, with "motley" appearing in Shakespearean works like (c. 1599) to evoke variegated, patterns in or appearance, paving the way for "mottle"'s adoption in descriptive contexts such as fabrics or natural textures. Over the 19th and 20th centuries, it shifted from these everyday and artistic descriptions to specialized technical applications in fields like and industry, where it precisely denotes irregular color distributions.

Natural Occurrences

In Plants

Mottling in plants refers to irregular patterns of discoloration on leaves, often appearing as yellowish or chlorotic spots interspersed with areas, which can serve as an early diagnostic indicator of underlying biological or . This phenomenon disrupts the uniform coloration typical of healthy foliage and is particularly prevalent in agricultural and ornamental , where it signals potential threats to vitality. Viral infections represent a primary cause of mottling, with potyviruses such as Tobacco vein mottling virus (TVMV) inducing vein clearing and mosaic-like patterns on tobacco leaves, leading to light and dark green patches that vary in intensity across the plant. Similarly, Bean pod mottle virus (BPMV), transmitted by bean leaf beetles, causes green-to-yellow mottling and leaf distortion in soybeans and beans, often starting on younger upper leaves and progressing to puckering in severe cases. These viruses interfere with synthesis and cellular function, resulting in symptoms that range from small chlorotic flecks to extensive coverage of entire leaves. Nutritional deficiencies, particularly iron chlorosis, also trigger mottling by limiting production, manifesting as interveinal yellowing where veins remain dark green, creating a mottled appearance in crops like soybeans and ornamentals grown in alkaline soils. Environmental stresses, such as waterlogging, exacerbate this by inducing hypoxia and secondary nutrient uptake issues, like iron unavailability, which leads to patchy and patterns on affected leaves. These non-infectious causes produce visual traits akin to viral mottling but lack the systemic spread and vein-specific clearing often seen in pathogen-induced cases. The implications of mottling extend to reduced , as chlorotic areas contain less , impairing light capture and carbon fixation, which in turn diminishes overall growth and crop yields. For instance, TVMV in can cause severe malformations and yield losses exceeding 50% in susceptible varieties, while BPMV in soybeans reduces seed size, quality, and germination rates, impacting harvests by up to 25%. In agricultural contexts, these effects highlight mottling as a critical symptom for timely intervention to prevent widespread economic damage. Hereditary mottling, observed in ornamental plants like certain camellias or variegated foliage varieties, arises from genetic chimerism or mutations that stably alter pigment distribution, producing desirable mosaic patterns without pathogenic harm. In contrast, pathogenic mottling in crops such as and s is detrimental, driven by infectious agents that propagate systemically and require management strategies like resistant cultivars or , underscoring the distinction between benign aesthetic traits and disease indicators in plant cultivation.

In Animals and Humans

In humans, skin mottling, also known as dyschromia, manifests as irregular, blotchy discoloration often resulting from impaired flow or pigmentation irregularities. This condition can arise from ischemia, where poor peripheral circulation leads to heterogeneous in small vessels, producing a mottled appearance indicative of reduced skin microperfusion. , a common pattern of mottling, appears as a reddish-blue, net-like discoloration due to vascular spasms or flow disturbances near the skin surface, frequently triggered by exposure, use, or emotional stress, and is more prevalent in women aged 20 to 50. Pathological causes include conditions like Raynaud's disease, where episodic results in purplish mottling from small vessel occlusion, reversible upon rewarming. In severe cases such as or , mottling reflects systemic hypoperfusion and serves as a prognostic marker, correlating with prolonged hospital stays and higher mortality; the skin mottling score () quantifies its severity to assess peripheral tissue perfusion. Aging contributes to mottled pigmentation through , where chronic sun exposure causes uneven melanin distribution, leading to speckled or blotchy patterns like senile , a hallmark of epidermal changes in individuals over 60. Rarely, herpes zoster () may present with localized mottled skin discoloration along affected dermatomes due to varicella-zoster virus reactivation. In animals, mottling often stems from genetic mutations affecting pigmentation or vascular patterns, particularly in domestic species like horses. The champagne gene, caused by a in the SLC36A1 gene, produces a diluted color with mottled, varnish-like roaning and pinkish-lavender that develops freckled speckling with age, especially around the muzzle and eyes. Similarly, or leopard complex spotting pattern results in variable white spotting over pigmented areas, accompanied by mottled , striped hooves, and white sclerae, inherited as an autosomal dominant trait. Disease-related mottling in animals signals underlying , such as circulatory compromise in , where heterogeneous mirrors human presentations and indicates poor in critically ill dogs and cats. In , these patterns aid diagnosis; for instance, mottled skin in horses or small mammals can denote vascular issues or infections, prompting assessment for hypoperfusion or systemic illness. Mechanisms generally involve genetic alterations disrupting production, vascular dysregulation causing blotchy red-blue patches, or inflammatory responses leading to irregular pigmentation, with clinical value in monitoring conditions like endotoxemia or shock.

In Geology

In geology, mottling describes irregular, patchy color variations in rocks and soils arising from heterogeneous mineral compositions and post-depositional processes. These patterns often reflect variations in iron oxides, carbonates, or other minerals that alter the visual uniformity of the material. Mottling forms through several key mechanisms. Bioturbation, the mixing of sediments by burrowing organisms, disrupts primary layering and produces mottled textures in sedimentary rocks, particularly in low-sedimentation environments where biological reworking is extensive. Oxidation-reduction (redox) processes in waterlogged soils generate distinct mottles during gleying, where alternating wet and dry conditions reduce and re-oxidize iron, creating blotchy patterns of gray matrices with red or yellow spots. Weathering contributes by differentially breaking down minerals, such as through carbonation in limestones, leading to color contrasts from uneven dissolution or secondary mineral precipitation. Examples of mottled formations include bioturbated limestones, where burrowing in the Cresswell Limestone of created irregular mottling from organism activity during deposition. In soils, mottles appear as red-gray concentrations within a gleyed matrix, signaling prolonged saturation and serving as key indicators of hydric conditions in wetlands. Mottling holds significant value in environmental reconstruction, as preserved patterns in paleosols reveal past conditions, such as and drainage regimes, through analysis of iron mobilization and development. In , these features are essential for classifying hydric soils, enabling the identification of boundaries and assessment of for ecological and .

Human-Made Contexts

In Food Processing

In , mottling refers to irregular discoloration or spotting on the surface or within products, often manifesting as a defect that compromises visual uniformity. This phenomenon arises primarily from enzymatic reactions, microbial activity, and inconsistencies in conditions, leading to uneven distribution in items like , fruits, and preserved goods. Common causes include enzymatic browning, triggered by (PPO) enzymes oxidizing in the presence of oxygen, which results in localized brown spots particularly in fruit-based products. Microbial contamination contributes through uneven growth of molds, yeasts, or on surfaces, as seen in items where surface microorganisms create patchy pigmentation. Uneven heating or mixing during production exacerbates these issues by allowing differential exposure to or ingredients, such as in churning processes where poor dispersion leads to spotting. Representative examples illustrate these defects: in , yellow-white mottling occurs from inadequate churning or uneven salt incorporation, resulting in undissolved salt grains attracting and creating streaks. Mottled cheese rinds develop from microbial during aging, forming a heterogeneous layer of light and dark patches due to varying bacterial and mold activity. In fruit purees, such as or apple varieties, enzymatic causes mottled discoloration if processing fails to fully inactivate PPO, leading to patchy during blending or storage. These defects pose significant implications for , as mottling signals processing inconsistencies that can reduce by promoting faster oxidation or microbial proliferation in affected areas, while diminishing consumer appeal through unappealing aesthetics. Regulatory standards, such as those from the FDA, emphasize uniformity in color and texture to prevent adulteration, with defect action levels for moldy or discolored products guiding acceptable thresholds to ensure safety and marketability. Specific processes influence mottling severity; for instance, lower levels inhibit enzymatic browning by reducing PPO activity, elevated temperatures during mixing speed up reactions leading to uneven pigmentation, and additives like salt or preservatives can induce spotting if not uniformly distributed. In animal-derived foods like and cheese, mottling may analogously reflect underlying physiological irregularities in source materials, such as uneven fat distribution in .

In Coatings and Printing

In coatings, mottling manifests as an undesirable uneven or clouding in effect paints, particularly pearlescent or metallic finishes, resulting from disorientation of metallic flakes during application. This defect is prominent in automotive panels, where variations in spray technique or formulation lead to blotchy appearances under . For instance, excessive evaporation or improper layering in solvent-based metallic s can cause floating of pigments, exacerbating the irregularity. In printing, mottling appears as a spotty or uneven in solid ink areas, often due to irregular ink transfer on textured substrates like . Specific types include mottle, which affects print uniformity, and gloss mottle, which varies surface sheen. In on textured , the rough surface disrupts even distribution, while offset processes suffer from back-trap mottle caused by nonuniform ink retransfer between units. Digital graphics can also exhibit mottling from inconsistent absorption on varied substrates. Common causes across both domains include substrate texture variations, which lead to uneven ink or paint adhesion; ink tack, influencing how quickly the material sets and transfers; and differential drying rates, promoting irregular pigment settling. In offset printing, for example, non-uniform paper porosity accelerates uneven ink vehicle absorption, while in coatings, high tack can cause metallic flakes to clump. Mitigation strategies involve process controls such as adjusting formulations to balance and tack for uniform application, and optimizing drying conditions to prevent rapid solvent loss. In , improving substrate uniformity through contour reduces back-trap issues, while in coatings, controlled spray patterns minimize flake disorientation. Industry standards, like ISO/TS 15311-2 for print mottle , define acceptable levels by quantifying low-frequency density variations, ensuring quality thresholds are met without over-specification. For coatings, instrumental assessments on panels of at least 30 x 50 cm help verify compliance with visual uniformity norms.

In Textiles and Camouflage

In textiles, mottling refers to the deliberate creation of irregular, variegated color patterns on fabrics through various dyeing and finishing techniques, enhancing aesthetic appeal in fashion and decorative applications. Common methods include processes like , where fabric is bound or folded to prevent uniform penetration, resulting in soft, mottled gradients of color, and , which employs wax resists to produce intricate, uneven patterns on or . These techniques yield fabrics with subtle shade variations prized for their organic, handcrafted look in apparel and home goods. Mottled effects are also achieved through direct application of dyes, such as ice dyeing or sprinkling powdered dyes onto pre-soaked fabric, which allows colors to bleed irregularly for a marbled or spotted appearance. In , these variegated textiles are used to create visual interest in garments like scarves, dresses, and , evoking a sense of movement and depth without bold prints; for instance, heathered or mottled weaves blend multiple shades during production to mimic natural tonal shifts. Historical applications in include West African variants like adire, where tied and dyed cloths were incorporated into ceremonial garments and wall hangings, preserving cultural motifs through intentional irregularities. Beyond aesthetics, non-military employs mottled patterns in civilian outdoor gear to blend with natural surroundings, such as apparel featuring subtle tree bark mottling for concealment in forested environments. Techniques like with slub yarns—intentionally uneven threads—contribute to mottled textures in or , adding tactile variation while maintaining durability. Chemical spotting, involving localized dye applications or washes post-dyeing, further refines these effects in modern production. Examples of mottled textiles span natural and synthetic materials: traditional wool fabrics often exhibit mottling from hand-dyeing or variations during processing, used in rustic and folk rugs for an aged, authentic . In contemporary outdoor apparel, synthetic blends like polyester-nylon weaves incorporate mottled finishes to provide low-profile for activities like , balancing functionality with subtle style.

Measurement and Analysis

Techniques and Instruments

Techniques for quantifying mottle patterns objectively often involve optical scanning of surfaces to capture variations, typically using white LED illumination at angles such as 15°, 45°, and 60° relative to the to simulate different viewing conditions and emulate human perception. These methods scan the sample over a roll-over distance ranging from 10 to 100 cm, dividing the captured data into spatial frequency components to assess non-uniformities across scales. Specialized instruments, such as mottling meters, facilitate precise measurement by analyzing images or data. For instance, the OpTest Mottle Analyzer (OMA) scans solid print or areas up to 100 × 100 and decomposes mottle into six size ranges spanning 0.5 to 16 (specifically 0.5 , 1 , 2 , 4 , 8 , and 16 ), enabling calculations of a mottle index (M) that quantifies overall variation. Similar devices, like the BYK-Gardner cloud-runner, employ line-scan cameras to detect lightness fluctuations in paints and coatings, providing objective rankings that correlate with visual assessments. The mottle value is commonly computed as the standard deviation of optical density values, where the image is divided into non-overlapping square (e.g., 1.27 × 1.27 per ISO guidelines), and the density per tile is used to derive the index: M=1n∑i=1n(mˉi−mˉ)2M = \sqrt{\frac{1}{n} \sum_{i=1}^{n} ( \bar{m}_i - \bar{m} )^2 }
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