A metameric pair assessed only under a shop's fluorescent lighting may
Answer: A
The customer will see the goods under quite different light at home. Assessment under a single illuminant systematically misses this risk. Goods are worn under quite different light. End use is what should govern the assessment.
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Assertion (A): Assessment should use the illuminants under which the goods will be seen.
Reason (R): A pair may match under one and fail badly under another.
Answer: B
Both are true and the reason gives the reason, and complaints arise from the end use condition. Shop and daylight conditions are both commonly specified. End use governs which illuminants matter. Both shop and daylight are commonly required.
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A retailer specifying assessment under D65 and F11 is
Answer: C
Correct answer: anticipating both daylight and shop lighting conditions
D65 represents average daylight and F11 a narrow-band fluorescent of the kind used in retail, so specifying both requires the match to survive the two conditions the goods will actually be seen under. It is a practical constraint on metamerism, stopping well short of demanding a spectral match.
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Consider the following statements about multi-illuminant tolerances.
1. Requiring agreement under two illuminants limits metamerism.
2. It stops short of requiring a full spectral match.
3. It guarantees a match under every possible illuminant.
Answer: D
Correct answer: 1 and 2 only
Statements 1 and 2 are correct: agreement under two illuminants rules out recipes that fail badly between them, while allowing the curves still to differ. Statement 3 claims too much - a pair may agree under both specified illuminants and still fail under a third, since two constraints do not force the curves to coincide.
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Metamerism is most likely to be a problem when the standard and the batch
Answer: A
Correct answer: were produced using different colourants or substrates
Metamerism requires a spectral difference, and a spectral difference arises when the materials differ. Identical colourants on identical substrates give identical curves and cannot be metameric, however they are measured. Measuring on the same instrument affects the measurement, not the samples.
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Assertion (A): Matching a shade across two different fibre types is inherently metameric.
Reason (R): The same dye behaves differently on different fibres and different dyes must be used.
Answer: B
Correct answer: Both A and R are true, and R is the correct explanation of A
Both are true and the reason gives the mechanism. A dye that works on cotton will not fix on polyester, so a shade matched across the two fibres must be built from different dyes with different absorption spectra. The curves therefore cannot coincide, and the match is metameric from the outset - which is why two-fibre garments are assessed under several illuminants as a matter of course.
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A garment whose body and trim match indoors but not outdoors demonstrates
Answer: C
The two components are made of different materials with different spectra. It is among the commonest consumer complaints in the clothing trade. Body and trim are frequently different materials. The complaint arrives after purchase.
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Three of the following are situations likely to produce metamerism. Which is the odd one out?
Answer: D
Correct answer: producing two batches with the same recipe and materials
The other three all match across a spectral discontinuity - dyed against printed, one fibre against another, paint against plastic - and each forces different colourants. Two batches of the same recipe on the same substrate share a reflectance curve, so any difference between them is a straightforward colour difference rather than a metameric one.
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Batch to batch variation within one recipe is generally
Answer: A
Small changes in concentration scale the curve rather than reshaping it. Metamerism arises when the shape rather than the level differs. Concentration scales the curve without reshaping it. Shape change is what causes metamerism.
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Assertion (A): Concentration variation within a recipe produces little metamerism.
Reason (R): It scales the reflectance curve rather than changing its shape.
Answer: B
Both are true and the reason gives the distinction, and shape change is what causes metamerism. Substituting a colourant changes the shape directly. Shape change is what produces metamerism. Level change produces comparatively little.
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