Prints, slides and negatives: scanning them and keeping the originals

How to handle old prints, slides and negatives, scan them at a stated setting to files that keep everything the scanner saw, capture the writing on the backs, and store the originals where they will last.

What a scan replaces, and what it does not Understand

A scan is a digital picture of a physical photograph, made by a machine that measures the light coming off (or through) it, point by point. It lets you copy, back up, share and caption a photo that otherwise exists once. It does not replace the original. The National Archives says to keep your originals after you digitize them, because digital files have their own preservation risks and can easily be lost (NARA's Digitizing Family Papers and Photographs). The Minnesota Historical Society's brochure says there is no substitute for an original photograph and asks families not to discard photos after digitizing (MNHS's Digitizing Your Family Photographs). So this chapter has two halves that go together: make a good scan, then keep the original well. Convention

The original also holds clues a scan of the front misses: writing on the back, the paper, the mount, the size and the border (Dates, captions and people uses them).

Start small

Not everything needs scanning, and nobody has to do a whole box at once. A University of Nebraska Medical Center library workshop puts it plainly: not everything needs to be digitized, start small, try a pilot project, and define why you are doing it (UNMC's Preserving Family Treasures slides). A first batch of 20 prints or one envelope (this manual's size) teaches you the scanner and shows how long a scan takes. Preference

Handling prints, slides and negatives

A photograph is a thin image layer on paper, plastic or glass. Skin oils, grit, ink and pressure leave marks that a scan then records.

• Clean, dry hands or nitrile gloves. The Library of Congress says to handle photographs with clean hands or clean nitrile gloves (LoC's Care, Handling and Storage of Photographs). The National Archives says to handle photographs and negatives with gloves, because fingerprints can cause permanent stains (NARA's handling tips). Our default: nitrile gloves for negatives and slides, and either gloves or freshly washed, dry hands for prints. Convention
• By the edges. LoC says to hold a photograph by its edges or its housing whenever possible. For a slide, the housing is its mount.
• A clean, dry table with no food or drink. LoC asks for a clean, dry, organized work area free of food and drink.
• No clips, rubber bands, tape or sticky notes. LoC says not to use paper clips, rubber bands or other fasteners on prints, or any tape, sticky note or glue.
• Dust off gently. Minnesota suggests a rubber air blower for dust before scanning. Wiping a print with a cloth or a sleeve can drag grit across it.

None of the three says cotton gloves; LoC names nitrile, and the National Archives and the Northeast Document Conservation Center say gloves or clean hands without naming cotton (NEDCC's leaflet 5.3, Care of Photographs).

Writing on photographs

Our default is to number the envelope, folder or box, not the photos. LoC says to limit markings, to write on the back near the edge with a soft graphite pencil if you must, and that marking the photograph's housing is preferable. NEDCC agrees that an ordinary lead pencil on the back, along the edge, is best for most prints, and notes that plastic-coated (resin-coated) papers need a pencil or marker made for that surface, which its leaflet names. The National Library of Australia's talk hopes for soft pencil rather than ballpoint on the backs it reads. Convention

Scanners and phone apps

A flatbed scanner is a scanner with a glass plate: you lay the original face down on the glass and close the lid. It is what the sources recommend for photos. The National Archives says the original must fit completely on the glass, because the lid can crush and crease it, and that automatic-feed scanners are not suitable for fragile, weak, bent or valuable papers. Minnesota says to avoid office all-in-one copiers and sheet-fed or document scanners for photos, and to use a flatbed or a camera on a copy stand. Convention

• Clean the glass first. The Library of Congress's scanning handout says to clean the scanner glass and remove clips, staples and tape before you scan (LoC's Scanning Your Personal Collections). FADGI warns that dust on the glass ends up in the file.
• Film needs light through it. A print is scanned by light bouncing off it. A slide or negative has to be lit from behind, so a flatbed scans film only if it has a film lid or adapter; a film scanner is built for it. Physical principle Check your scanner's specifications before buying film holders.

Phone apps

A phone photographs a print rather than scanning it. Minnesota calls smartphone apps inferior in nearly every sense except convenience, and useful when you are borrowing a relative's photos for an afternoon. Google's PhotoScan is still listed in both app stores, but it has not been updated since July 2023 on Android (PhotoScan on Google Play) and November 2022 on iPhone (PhotoScan on the App Store). Apple's scanner in Notes and Files is documented as a document scanner, for papers and signing; Apple's page says nothing about photographs (Apple's How to scan documents on your iPhone or iPad). Product Our default: a flatbed and a computer for anything you mean to keep; a phone app for a borrowed print you cannot take home, labeled as a phone copy on the scanning log.

Scan settings: resolution, color and file format

Three settings decide what a scan keeps: pixels per inch, how much color each pixel records, and whether saving throws any of it away. Set them once and write them on the scanning log's settings sheet.

These are this manual's defaults, chosen from named institutions' settings. Convention

Resolution

ppi (pixels per inch) is how many pixels the scanner records along each inch of the original. Scanners often say dpi (dots per inch) for the same thing. A 4 by 6 inch print at 600 ppi becomes 2,400 by 3,600 pixels.

The sources give a ladder rather than one number. The Library of Congress's handout says 300 ppi in general for 4 by 6 and 5 by 7 photos, and 400 or 600 to enlarge them to 8 by 10 or larger. Minnesota says 300 is fine in general and 600 for enlargement or for especially detailed or precious photos. FADGI, written for federal agencies, sets 400 ppi as the level it does not recommend going below and 600 as its best level for prints (FADGI's Technical Guidelines). We use 600 because a family snapshot is small and often the only one; the cost is time and four times the disk space of 300. With a very large box and little time, 400 (FADGI's floor) is the next choice. The ladder is under Go deeper.

Use the scanner's true optical resolution: the most pixels per inch its sensor actually records. Many scanners also advertise a much higher "interpolated" figure, which is the optical scan enlarged by software and adds no detail. A Library of Congress blog post quotes a photographer advising the optical figure, not the marketing one (The Signal, How Many DPI/PPI Is Too Much?). The same post records that very high settings on a small print mostly show dust and defects, which is why we stop at 600 for prints. Your scanner's specification sheet gives the optical figure; write it on the settings sheet.

Color

24-bit color records 8 bits for each of red, green and blue. Minnesota's rule of thumb is that every photo you digitize should be in color, sepia and black and white included, because color files record more detail and can be turned into grayscale, while grayscale files cannot gain the color back. Physical principle Institutions scan at 16 bits per channel (48-bit color), which doubles the size; that is under Go deeper.

File format: a lossless master and a sharing copy

A lossless format stores every pixel exactly as captured. A lossy format such as JPEG makes files smaller by discarding detail the eye is unlikely to miss, and discards more each time an edited file is saved again. The master is the scan you keep untouched; a sharing copy (also called an access copy) is a smaller copy made from it.

• TIFF is a lossless format that museums use for masters, Minnesota says, and a Library of Congress post calls saving scans as TIFF good practice because it is lossless (The Signal, What People Are Asking About Personal Digital Archiving). PNG is a smaller lossless option Minnesota also names.
• JPEG is for the copies you send and post. Minnesota says JPEG is not a good format for archiving.
• Edit only copies. Minnesota says not to overwrite the original scan when editing, and to save edits under a new name; the Library of Congress post says the same about any original. FADGI says dust removal, color correction and restoration belong on access copies, not masters. If your scanning software has dust removal or color restoration switched on, turn it off for the master. Convention

How big the files are

An uncompressed 24-bit TIFF takes 3 bytes per pixel. Lossless compression makes real files somewhat smaller. The scan size calculator does this arithmetic for your own sizes and counts.

So 600 prints at 4 by 6 come to about 16 GB of masters, before any copies. That is our arithmetic (pixels times 3 bytes, with a megabyte as 1,000,000 bytes), not a figure from a source. The 300 ppi print column uses the size rule in Minnesota's brochure and the Library of Congress post on scanning services. Every copy you keep in Backups needs the same space again.

The backs, and naming the scans

The back of a print often carries the only record of who is in it and when: a name, a date, a place, a processing lab's stamp. The National Library of Australia's talk on dating photographs lists writing on the front or back among its main clues (NLA's Finding and dating photographs), and NEDCC's labeling advice is about writing on the reverse. A scan of the front alone loses all of it.

So this manual's step is to scan the back of every print that has any writing or stamp on it, at the same settings, and to save it beside its front. None of the archive guides we read tells families to do this; it is this manual's rule, built on the point that the information is often on the back. This manual's rule A back with nothing on it does not need a scan; a single line in the batch notes saying "backs blank" is enough.

• Name the back so it sorts with its front. If the front's name ends in _012.tif, the back's ends in _012-back.tif, with the rest of the name the same. Our convention, so a reader of the folder sees the pair together. Convention
• Copy the writing into the caption. A scan of handwriting is hard to search. Type what it says into the photo's caption in Dates, captions and people, and note "from the back, in pencil".
• Tick "backs captured" on the batch's row in the scanning log.

Naming the scans

Scans go into a folder per batch, named date first, so batches sort in order. The National Archives' rule for file names is Latin letters only, no spaces, punctuation or symbols, with hyphens and underscores instead of spaces, and the Library of Congress handout's example names begin with the date. This manual's pattern, and how to name a scan whose date is only an estimate, are in Folders and file names. Many scanning programs number files in order; keeping those numbers keeps the files in the order they came out of the envelope, which is itself information. Convention

Scanning services

A scanning service is a business that scans prints, slides or negatives for a fee. We do not name one, and the Library of Congress does not either: a 2013 post on its blog says it cannot recommend commercial services and lists what its author would consider (The Signal, Scanning: DIY or Outsource). A service can scan at the settings in this chapter if you ask for them. Preference

The questions, from that post and this chapter:

1. Cost per scan, and what counts as a scan (a slide, a print, a print's back).
2. Resolution. The post says commercial resolutions range from 300 to 3000 dpi. Ask for 600 ppi for prints and 3000 for 35 mm film, in writing.
3. File format. TIFF masters and JPEG copies. The post calls TIFF a good long-term format when file size is not a concern.
4. Delivery. How the files come back (a drive, a download) and for how long a download stays available.
5. Handling. How the company handles originals, and whether they come back in the order sent.

The post also says mailing services carry no guarantee of safety or security, and suggests a local drop-off if that concerns you. Before anything leaves the house, count the items in each envelope and write the count on the scanning log (this manual's step), so you can check the return. More is under Go deeper.

Storing the originals

Photographs decay through chemistry, which speeds up with heat and moisture. NEDCC says the chemical deterioration of most photographic materials roughly doubles with each 10°F rise in temperature. Physical principle

Our default target is the one the Library of Congress and NEDCC share: 70°F or below and 30 to 50 percent relative humidity (the amount of moisture in the air compared with the most it could hold at that temperature), with as little swing as possible. The National Archives' family pages give the outer limits for a home: below 75°F, and below 65 percent relative humidity to prevent mold (NARA's Storing Family Papers and Photographs). Convention

Enclosures and boxes

An enclosure is whatever touches the photo: a sleeve, an envelope, a folder, an album page. Photo-safe is a defined term: materials that pass the ISO 18902 standard, including the Photographic Activity Test (PAT), a test of whether a material causes fading or staining in photographs. The Image Permanence Institute's guide explains that photo-safe takes several tests, not only a pH test, so "acid-free" alone does not mean photo-safe (IPI's photo-safe guide). Look for "passes the PAT" on the label. Convention

• Plastics: uncoated polyester, polypropylene or polyethylene only (LoC, NEDCC). NEDCC and the National Archives both say to avoid PVC.
• One item per enclosure, with prints and negatives kept apart, says NEDCC.
• Most prints lie flat in a box, NEDCC says, rather than standing on edge.
• Self-stick "magnetic" albums out. LoC, NEDCC and the National Archives all advise against them; NEDCC says their pages are often acidic and can bond to photographs. Do not pull prints off one; scan the page and ask a conservator if you want them out.
• Display copies. NEDCC says light damage is cumulative and irreversible. The National Archives says the best protection is to display copies and keep the originals in a box (NARA's Displaying Family Papers and Photographs); a print from your scan is that copy.

Label the box, not the photos: what is in it, the envelope numbers, and where the scans are. Write the box's place on the batch's row of the scanning log.

Wet, moldy or damaged photos

A flood, a burst pipe or a damp basement is the situation where acting quickly matters. The National Park Service's leaflet on wet photographs is written for people without training (NPS's Saving Wet Photographs).

1. Sort first. The leaflet's triage: if a photo can be reprinted from a digital file or an undamaged negative, reprint it and let the wet print go. Your scans are that digital file.
2. Act within 48 hours on the irreplaceable ones. The leaflet says mold can begin to grow within 48 hours. Its order is wet color prints first, then black-and-white prints, then negatives and slides.
3. Leave stuck photos stuck. Do not pull apart photos stuck to each other or to frame glass; the leaflet sends those to a conservator.
4. Rinse and air-dry. One at a time in clean water, without touching the image surface until it is dry, then face up on clean towels or blotter, or hung by the edges, with a fan and a dehumidifier running.
5. Freezing only after asking. Freezing is an option if you cannot treat photos within 48 hours, but the leaflet says not to freeze older or valuable photos without first consulting a conservator.

For everything else, the National Archives' rule is to contact a conservator if you cannot safely solve a problem with correct storage and handling, and it notes that apart from wet or pest-damaged items you have time to decide (NARA's Repairing Existing Damage). Its examples are items stuck together, mold, rolled items that tear when unrolled, and items in many pieces. The American Institute for Conservation's directory lists peer-reviewed members, searchable by specialty (Photographic Materials) and by distance (AIC's Find a Professional). Ask a conservator

See it: Ruth's shoebox and slides See it

Free pages that show the methods:

• Minnesota Historical Society, Digitizing Your Family Photographs: a two-page brochure with the color rule, formats and the size table.
• National Archives, Digitizing Family Papers and Photographs: keep the originals, the glass, file names, who-what-where-when.
• NEDCC, Care of Photographs: temperature, humidity, light, labeling and enclosures in one leaflet.
• National Park Service, Saving Wet Photographs: the 48-hour steps with pictures, worth printing before you need it.

Practice: scan a first batch Practice

Minimum: 20 prints scanned at your settings into one folder, the backs with writing scanned beside them, and the originals back in a labeled box in an interior closet. Time: one evening; time the first five scans and write the time down, because scanners differ. Materials: a flatbed scanner and a computer (or a phone app for a borrowed print), nitrile gloves or clean dry hands, a soft pencil, an envelope or box, a lint-free cloth for the glass, and the scanning log.

1. Fill in the settings sheet first. Scanner, its true optical resolution, 600 ppi for prints, 3000 for film, 24-bit color, TIFF master, JPEG copy. The sheet is seeded with these defaults; change what your scanner cannot do.
2. Clean the glass and clear the table. No food or drink; gloves on.
3. Scan the 20 prints into one folder, named for the batch, date first. Check the first file opens and its pixel size matches the table (a 4 by 6 at 600 ppi is 2,400 by 3,600).
4. Scan the backs with writing, named to sort beside their fronts. Write "backs blank" in the notes for the rest.
5. Box and label the originals, and put the box in an interior closet, off the floor.
6. Add a row to the batches sheet: envelope, items, kind, scanned, backs captured, where the originals are.

Your photos Your photos

Check your work Check your work

Criteria

• Does the settings sheet name your scanner, its true optical resolution, and the ppi, color depth and formats you used?
• Do the 20 files open, at the pixel size the setting should give?
• Are the masters TIFF (or another lossless format), with no dust removal or color correction applied?
• Does every print with writing on the back have a back scan beside it?
• Are the originals back in a labeled box in an interior room, and does the batches sheet say where?

Worked example

Ruth's settings sheet names her flatbed, 600 ppi, 24-bit color, TIFF and JPEG. Her first file opens at 2,400 by 3,600 pixels and is about 26 MB. Seven backs are scanned and named with "-back"; the batch row says "shoebox-01, 20 prints, backs captured, hall closet shelf, box 1". It passes. The sheet's line for film says "3000, or less if the scanner's optical figure is lower: not yet checked", because that is still open.

Common mistakes

• Scanning in grayscale to save space. The color is gone for good; scan in color and make a grayscale copy if you want one.
• Saving the master as JPEG. Every later edit and save loses a little more. Keep the TIFF; make JPEG copies.
• Leaving "restore color" or "remove dust" on. The master should be what the scanner saw. Corrections go on a copy.
• Throwing the prints away afterwards. The National Archives and Minnesota both say keep them.

What is still unresolved

Who is in the photos and when they were taken is Dates, captions and people. How to name scans with estimated dates is Folders and file names. Keeping the scans in more than one place is Backups, and whether TIFF still opens in ten years is Formats and the long term. A damaged print is a conservator's call.

Knowledge check and scenario

Checklist

• 20 prints are scanned to lossless files at my setting, the backs with writing are captured, and the originals are boxed and labeled.
• The settings sheet names my scanner, its true optical resolution, and the settings I used.
• The box is in an interior room, off the floor, and the batches sheet says where.
• I ran the scan calculator for the whole box and compared it with my drives' free space. (Go deeper; optional)
• I scanned one slide or negative at 3000 ppi and checked it at full size. (Go deeper; optional)