If you refer to a Steinway piano or a Taylor guitar, do you capitalize piano and guitar?
I couldn't think how to word a search for this information.
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Sign up to join this communityQuick answer: the descriptor should be lowercase for Steinway, and uppercase plural for Taylor.
Rationale:
Full titles of institutions and companies and the names of their departments and divisions are capitalized, but such words as school or company, as well as generic or descriptive terms are lowercased when used alone. Chicago Manual of Style, 13th ed. 1982.
Rather than try to decipher the rule, I suggest you write the name exactly as it is consistently written on the company's own website.
Steinway & Sons / Steinway pianos — Steinway consistently uses "Steinway & Sons the pianomaker; but note piano is is capitalized within some of their product names. Since 'piano' is not integral to the company name, it should not capitalized. To help your readers understand what is the full title, you could lengthen the descriptor by adding: "Steinway & Sons, the piano maker"
Taylor Guitars / (the) Taylor guitar(s) — The company name has the word "Guitars" as an integral part. From the website: "Taylor Guitars is a leading manufacturer of acoustic and electric guitars..." When talking about the company, 'Guitar' should be uppercase; when talking about the product, 'guitar(s)', should be lowercase; unless 'guitar' is integral to a particular product name.