HMRC's A to Z names business cards, and visiting, correspondence, membership and index cards with them. The card people expect to be zero-rated because it is printed is the clearest case of the 3.3 reasoning: it is kept, carried and used for a specific purpose in its own right, which is the wording HMRC gives for what a leaflet is not. It is also not distributed in quantity for general reading, which is another of the characteristics. Nothing about the finish changes it, and a card with a great deal of text on the back is still a business card.
What decides it?
Nothing you can print on it. Being kept and used is what it is for.
Where does this come from?
HMRC VAT Notice 701/10, section 8, HMRC's guidance on zero rating books and printed matter. See the notices we work from.
Some real jobs
500 business cards, both sides printed20%
Business cards are listed as standard-rated.
A business card with a mini price list on the reverse20%
Still a card kept and used, not a leaflet distributed to be read and discarded.
A folded card-sized leaflet for a door drop, printed in thousands0%
Judged as a leaflet: held and read, in quantity, short-lived.