Red -- predicate adjective or predicate noun? Or both?

[Lucky]

Posted this question in another forum. I probably should have put it here. Please have a look at it and tell me what you think. Thank you.

1. The color of her gown was such a red as makes the eyes ache.

I wondering whether "red" functions both as an adjective and as a noun. For instance, isn't an adjective modifying the sentence's subject "color"? And isn't it a noun, functioning as the antecedent of the relative pronoun "as"? Could "red" possibly have a dual function.
And also confusing me is the word "such." Is "such" an adverb modifying the adjective "red," or is it an adjective modifying the noun "red."

Thank you very much.

[Mister Micawber]

'Red' is the noun complement of 'color', and 'such(a)' is an adjective modifier of 'red'. 'As' is a conjunction to introduce the exemplifying clause.

[Casiopea]

Originally Posted by Lucky

Posted this question in another forum. I probably should have put it here. Please have a look at it and tell me what you think. Thank you.

1. The color of her gown was such a red as makes the eyes ache.

I wondering whether "red" functions both as an adjective and as a noun. For instance, isn't an adjective modifying the sentence's subject "color"? And isn't it a noun, functioning as the antecedent of the relative pronoun "as"? Could "red" possibly have a dual function.
And also confusing me is the word "such." Is "such" an adverb modifying the adjective "red," or is it an adjective modifying the noun "red."

Thank you very much.

In addition to MM's excellent reply, I'd like to add something small, but noteworthy. The article "a" tells us "red" functions as a noun: Only nouns take articles.

a red (article + noun = noun phrase)

As for "such", and as MM has noted, it functions as an adjective here. We know that because adjectives modify noun phrases:

such a red (adjective+noun phrase)

As for whether or not "red" has a dual function, please note that, the entire phrase 'such a red as makes the eyes ache' functions as the subject complement:

The color of her dress was such a red as makes the eyes ache.

As for whether the underlined portion functions as a predicate noun or a predicate adjective, here's a test that always works: Add the Subject complement to 'seems':

The color seems such a red as makes the eyes ache. (not OK)
She is a doctor / She seems a doctor. (not OK)

The underlined portion doesn't work with 'seems', so its not an adjective. (Only adjectives can occur in that position--after 'seems'.)

The underlined portion is a predicate noun and within that structure 'red' has its own separate function: noun (i.e., "red" is the name of a color).

All the best, :D

[Lucky]

I thank both of you very much, for your time and for sharing your knowledge.

[Casiopea]

You are very welcome. :D