I have the impression that for a long time scholars thought that ancient Greek and Roman sculpture was unpainted, and marble statues would be wholly white, but the modern consensus is that sculpture was indeed painted. The evidence I have seen mentioned for this is more or less visible trace amounts of paints on various archaeological findings. But is there any literary evidence on the matter? Did the Romans or Greeks write about painting their sculpture? Would written evidence alone be enough to debunk the myth of a white antiquity?
I doubt that anyone will want 'to debunk the myth of a white antiquity'. There seems to be a lot of evidence that such a myth doesn't have any substance and that, as in other ancient civilisations, Roman statues really were painted.
According to an article "Pictura" by Leonhard Schmitz in the Dictionary of Greek and Roman Antiquities (1882, ed. Wm. Smith) the term polychromy was apparently unknown to the ancients. Nevertheless, it is mentioned by Plutarch (De Gloria Athen. 6), and if it be true that Plato (De Republ.iv, 420, c) "alludes to painting statues, it is clear that they were occasionally entirely painted, in exact imitation of nature; for he expressly remarks, that it is not by applying a rich or beautiful colour to any particular part, that the whole is made beautiful."
Schmitz goes on to say that "the practice of colouring statues is undoubtedly as ancient as the art of statuary itself. . . The Jupiter of the Capitol, placed by Tarquinius Priscus, was coloured with minium* (Plin. H.N. xxxv.45). In later times the custom seems to have been reduced to a system." The theme is then developed and discussed at some length, with references and examples, proceeding to the Roman habit of painting buildings, followed by a disquisition on vase painting.
A long article "Statuaria Ars" in the same work, also by Schmitz goes into much detail, often very insightful, divided into five periods, of which the fourth covers 336-146 BC and the fifth from 146 BC to the fall of the Western Empire.
The whole discussion is reduced to more manageable size, also under the heading "Statuaria Ars", in the illustrated Concise edition of 1898 (ed. F Warre Cornish) based on Smith's larger dictionary "and incorporating the results of modern research". Early on, it adds "Where rough stone was used, colour was applied to all parts, more or less conventionally — red for the nude parts, and blue for hair, clothes etc. being the colours most used". Unfortunately, this edition gives no references, presumably relying on those in the version from which it was condensed — though it concludes with a list of some of the "numerous works bearing on ancient sculpture".
Although I cannot cite particular sources, I do know that the powerful modern techniques of chemical analysis have been used to identify the pigments used. If they were mixed in an organic medium, and if a sufficiently large sample is available, it may be that carbon dating can be applied.
- Minium is a naturally occurring lead oxide, varying in colour from a brownish yellow to a bright red. Used as a pigment it is reasonably stable, though atmospheric pollution may alter it.
Literary evidence would do little to "debunk the myth of a white antiquity", because such evidence would only refer to a subset of statues. Diehard whiteys could claim that other statues were unpainted.
Fortunately, the scientific evidence is overwhelming, e.g. https://hyperallergic.com/383776/why-we-need-to-start-seeing-the-classical-world-in-color/ or https://hyperallergic.com/159420/what-do-classical-antiquities-look-like-in-color/
In addition, back as far as the 1600s, contemporary accounts of statues unearthed at Pompeii record that they were brightly colored, but that the colors soon faded with exposure to air (and no knowledge of preservation techniques).