Shipping label prints faded or too light

Grey where it should be black, patchy across the label, or perfectly readable today and unreadable by Friday. Faded thermal output has four causes and they are easy to tell apart once you know what to look at.

Start here: the fingernail test

Before changing any setting, confirm the roll can darken at all. Tear off a label and scratch it firmly with a fingernail, a coin or a key.

• It goes grey where you scratched. The stock is direct thermal and works. Friction heat did what the print head does — carry on below.
• Nothing happens on either side. The stock is thermal transfer and needs a ribbon. In a printer without one it will never produce a usable label, whatever you set.

This takes two seconds and rules out the cause no amount of driver tinkering can fix.

1. Density is too low

The most common cause and the easiest to correct. A thermal printer prints by applying heat, and the density or darkness setting decides how much.

Raise Darkness or Density in the printer preferences by two steps, print a test label, and repeat if needed.

Resist jumping to maximum. Too much heat bleeds the ink outwards, which closes up the gaps in a barcode and fails at the scanner just like a faded one. There is a window, and stepping into it beats overshooting.

Speed matters here too, where the printer exposes it. Faster printing gives each dot less time under the head, so a printer set to run quickly needs more density to reach the same darkness.

2. The print head is dirty

Distinctive symptom: the fade is not even. Thin unprinted lines run down the label in the same place every time, or one band is consistently lighter.

Adhesive, paper dust and grit collect on the head and sit between it and the label. Clean it with isopropyl alcohol and a lint-free cloth or a cleaning pen, with the printer off and the head cool.

If a gap survives cleaning and stays in exactly the same position, those heating elements have failed. That is a head replacement rather than a setting, and on a cheap printer it is usually not worth it.

3. The roll is old, or was stored badly

Direct thermal paper has a shelf life. The coating reacts to heat — that is the entire mechanism — so it also reacts to warmth in storage, sunlight through a window, and time.

A roll kept in a hot room or a car for a season prints greyer than a fresh one at the same density. If output has drifted lighter over weeks with nothing changed, try a new roll before adjusting anything.

Store rolls somewhere cool, dark and dry, and buy in quantities you will actually use.

4. It fades after printing, not during

A different problem with the same word attached. The label printed correctly and lost contrast afterwards.

Nothing is wrong with the printer. Direct thermal keeps responding to heat and light after the fact: a parcel in a sunny window, a warm vehicle or a summer depot will fade a label that was perfect when printed.

For ordinary parcels shipped within days this rarely matters. For labels that must stay readable for weeks — long transit, outdoor storage, archive tags — direct thermal is the wrong stock, and thermal transfer with a ribbon is the durable answer.

What it is not

Fading is a hardware and consumables problem. It is not caused by the PDF, the print scale, or the paper size. If your label is also the wrong size, that is a separate fault with a separate fix — check the page size in Preview and crop it if it arrived as a full page.

If nothing helps

Print the printer's own self-test, usually a button combination at power-on. It bypasses the Mac completely.

• Self-test is faded too. The printer or the roll. Work through the four causes above.
• Self-test is crisp. The printer is fine and the density is being overridden somewhere on the Mac — check the driver preferences rather than the app you printed from.