Faded mineral labels
Thermal receipt paper goes blank entirely; felt tip and blue ballpoint fade in a lit cabinet within years. Photograph the label before you touch anything else.
Faded mineral labels usually fail for one of five reasons, and the commonest is thermal receipt paper, which goes blank with heat, light or friction. Dye inks are next: the conservation literature places most felt tip pens and blue ballpoint in its highest light-sensitivity class, fading at 150 lux within half a year to 7 years. A specimen without a readable label has lost its locality and its provenance.
In short
- Photograph the label before you do anything else, in raking light, at full resolution, both sides. A faded label is a decaying record and every hour it spends out of a folder is more decay. This costs nothing and cannot be undone later.
- Never rewrite an original label. Make a new label, keep the old one with the specimen in a sleeve, and record on the new one that it was copied and when. The old handwriting is the provenance; a tidy transcription is not.
- Thermal paper is the commonest failure and it is total. Till-roll and thermal printer labels darken chemically rather than carrying ink, and the image disappears under heat, light, solvents and even the plasticiser in a PVC sleeve.
- Dye inks fade and pigment inks do not. The CCI places most felt tips, including blacks, and most red and blue ballpoint inks in its high-sensitivity class. Carbon pigment ink is in the most stable class and costs no more.
- Ink is not the only thing that fails. Acidic, lignin-rich paper browns, and brown paper with grey ink is unreadable even when the ink has not moved at all. Contrast is what you are preserving, not pigment.
| Cause | What you see | The test that confirms it | What to do |
|---|---|---|---|
| Thermal receipt paper | Text gone completely, paper otherwise clean, sometimes an overall grey cast | Scratch an unused corner with a fingernail — thermal paper darkens where you scratch it | Nothing recovers it. Photograph immediately, and never store thermal paper against PVC or in a warm place |
| Dye-based ink: felt tip, most blue and red ballpoint, dye inkjet | Colour lost first, black felt tip going brown or grey, blue going pale | Compare the covered part under the specimen or the folded edge with the exposed part | Photograph, make a pigment-ink copy, store the original away from light |
| Light exposure on open display | Fading strongest where the light fell; sharp shadow lines from the specimen or a stand | The shadow line itself — a fade that stops at a straight edge is a light fade | Move the labels out of the lit case. Display a copy, keep the original dark |
| Acidic, lignin-rich paper | Paper browned to a tea colour, ink largely intact but no longer readable against it | Browning is worst at the edges and along a fold, where oxygen reached it | Photograph in raking light and try a colour channel separation. Rehouse in an inert sleeve |
| Damp, water, or adhesive | Ink run or feathered, tide marks, a label stuck to the specimen or to a box | Look for a tide line — a hard edge with darker deposit along it | Do not attempt to soak it off. Photograph, then get advice before any treatment |
'My mineral labels have faded' — the five causes, commonest first
The phrase people search is a symptom, and it has five different diseases behind it. They are worth separating, because the response differs and two of them are recoverable while one is not.
Thermal receipt paper is the most common and the worst. It carries no ink at all: the image is a chemical reaction in a coating, triggered by heat from the printer head. Heat, light, friction, solvents, oil from fingers and the plasticisers in PVC sleeves all continue that reaction until the whole sheet is either blank or uniformly dark. There is no recovery. If any of your labels are till-roll or thermal printer output, photograph them today.
Dye ink is second and is what most people mean. The Canadian Conservation Institute's note on light places, in its highest-sensitivity class, most felt tip pens including blacks, most red and blue ballpoint inks, and many cheap synthetic colourants in all media. For that class it gives just-noticeable fade at 150 lux in roughly half a year to 7 years, and at 50 lux in 1.5 to 20 years.
Light exposure is third and is really a modifier on the second, but it is worth its own line because it leaves a signature: a fade with a hard shadow edge where the specimen or a stand covered part of the card. If you can see a sharp line, you know the mechanism, and you also have an unfaded reference patch for a photograph.
Paper browning is fourth, and it is the one people misdiagnose as fading. Acidic, lignin-rich card yellows and browns, and grey pencil on tea-coloured card is unreadable even though the graphite has not moved at all. You are preserving contrast, not pigment.
Damp and adhesive are fifth — run ink, tide marks, a label glued to a specimen. This is the one where amateur intervention does most harm.
What to do in the first hour, before any decision about treatment
Photograph everything, now. Not the ones that look bad — everything. This is reversible, free, and the only step that gets harder the longer you leave it.
Do it properly: full resolution, flat, both sides of the card, in even light for the record and again in raking light from a low angle, because a pen that has faded chemically often left a physical impression in the paper that raking light picks up when the eye cannot see the ink at all. A specimen number pressed into card with a hard pencil is frequently legible in a raking-light photograph and invisible in the hand.
Then, before treatment of any kind: write the new label and keep the old one. The new label carries the information, the date it was copied, and the fact that it is a copy. The old label goes into an inert sleeve and stays with the specimen. This is the point our page on what ex coll. means on a label keeps returning to: an old label is evidence, and its value lies in the handwriting, the printed letterhead and the paper, not only in the words. A collector who transcribes a faded Victorian dealer's label neatly onto a new card and throws the original away has destroyed the provenance and kept the data.
Only after that is it worth trying to read what is left. Two things sometimes work and neither touches the object: photographing through a coloured filter or separating the colour channels of the photograph afterwards, which can lift pale blue ink off brown paper; and raking light, as above. Anything involving solvents, bleaching or wetting should go to a paper conservator, and for a label worth that trouble it is worth the call.
What to write the next one with, so this does not recur
The replacement is a two-minute decision that determines whether your labels outlive you.
Ink: carbon pigment, not dye. Pigment ink suspends solid particles rather than dissolving a colourant, and the CCI's stability classes put carbon-based media at the top. A pigment fineliner or a technical pen is what you want. Ordinary blue ballpoint and every felt tip, including the black ones, are in the class that fades.
Pencil is better than most people expect. Graphite is essentially permanent, and a hard pencil on good card will outlast almost any ink. Its weaknesses are smudging and low contrast, which argue for a soft-ish grade written firmly and stored flat.
Paper: acid-free, lignin-free, reasonably heavy. Browning destroys contrast independently of the ink, and thin card creases along a fold and then tears along the crease.
And do not print labels on thermal paper, ever, including the sticky thermal labels that come with cheap desktop label printers. They are excellent for parcels and unusable for records.
The rest of the system — the number that must never change, the three certainty states, recording the date a species determination was made — is on our page on labelling and cataloguing a collection, which is where to go next if you are rebuilding a whole set of labels rather than rescuing a few.
Where the labels should live, and the display compromise
Labels fade in cabinets for the same reason specimens do, and the fix is the same arithmetic.
Exposure is a dose: illuminance multiplied by hours. At 150 lux for 4 hours a day a label in a case collects 0.219 million lux hours a year; at 50 lux it collects 0.073. For the high-sensitivity ink class that covers most felt tips and blue ballpoints, that is the difference between visible fading in a few years and visible fading in a couple of decades. Our note on lighting a display cabinet works the calculation through.
But there is a real tension here, and the honest answer is a compromise rather than a rule. A display where the labels are in a drawer is a display that will eventually orphan them, and an orphaned label cannot be reunited with its specimen. So the label has to be in the case, visible, with the piece.
The resolution is to display a copy and keep the original dark. A pigment-ink or laser-printed copy in the case, the original in a sleeve in a folder with the catalogue, cross-referenced by the specimen number that never changes. The copy can fade and be reprinted. The original never sees a lumen.
That arrangement also solves the succession problem, which is the one that actually destroys collections: the person who inherits a boxed collection with a folder of original labels and a catalogue has something intelligible, and the person who inherits a cabinet of beautiful specimens with blank cards has a pile of rocks. Our page on inheriting a mineral collection is written from the receiving end. If you are trying to reunite specimens with provenance you can no longer read, that is a specific brief and worth stating on a wanted list, because dealers and collectors sometimes hold the other half of a dispersed collection's paperwork.