What does 'convert type to curves' actually do?

It turns each letter into a vector shape, so the press no longer needs the font. The artwork can then be opened on any machine and prints exactly as approved. The trade-off is that the text is no longer editable, so keep an un-outlined master.

Why shouldn't small text be rich black?

Rich black mixes several inks. On small text, a fraction of a millimetre of misregistration shows as coloured fringes around every letter. Small black text should be 100% K alone, and set to overprint.

Is a digital proof enough?

For a few hundred cards, usually yes. For a long run, for packaging, or for anything where a brand colour has to be exact, ask for a hard proof on the real stock even if it costs a day.

Pre-Print Checklist: What to Check Before Artwork Goes to Press

Pre-Print QA Checklist

Before artwork goes to press, check nine things: bleed on every edge that runs off, text inside the safe margin, resolution at final scale, CMYK not RGB, type converted to curves, rich black on large areas only, overprint on small black text, barcodes at full size, and a physical proof on the real stock.

Every item here exists because it has gone wrong somewhere, for someone, at cost. Run the list once and it takes ten minutes. Skip it and you learn which item you needed the hard way.

Geometry

3mm bleed on every edge that runs off — 5mm for stack-cut items
Nothing critical within the safe margin
Nothing important crossing a fold, a glue flap or a spine
Crop marks present, offset clear of the bleed
Dieline on its own non-printing layer

Colour and ink

Document in CMYK, not RGB
Spot colours named and declared, or converted deliberately
Rich black only on areas larger than a thumbnail, never on small text
Small black text set to overprint, so a misregistration does not show white edges
Total ink coverage within what your press allows

Type and images

All type converted to curves — critical for Urdu and Arabic
Nothing below 6pt, and nothing below 7pt where the surface curves
Images at 300 dpi at final scale, or 30 dpi at 1:10 for large format
No images linked from outside the file
Barcode at 100%, quiet zone clear, dark on light

Before the run

Exported as PDF/X-4 unless your printer asks for something else
Opened the exported PDF and looked at it — not just the source file
A physical proof approved on the real stock for anything where colour matters