How to Store Microscope Slides

The standard microscope slide is nominally 75 × 25 mm (3″ × 1″). That is the figure every purpose-built slide box, tray and cabinet is cut around, including the Eberbach range — the E2870 tray is specified for 75 × 25 mm slides.

Larger formats exist. Double-width and oversized slides used for whole-mount and some neuropathology work will not sit in a compartment cut for a standard slide, so check the format of your own material before buying storage for it. If your collection mixes formats, plan to store the oversized ones separately rather than forcing them.

The common failure modes are chipped edges, scratched specimens and displaced cover glasses. All three come from slides moving against each other or against a hard surface.

• Store slides flat, one to a compartment. An individual compartment stops slide-on-slide contact and keeps the cover glass from being dragged sideways. Every Eberbach tray is compartmented for this reason.
• Give freshly coverslipped slides time before filing them. Mounting media cure at different rates; leave new slides flat until the mountant has set according to its own documentation, then file them.
• Avoid loose stacking. A pile of slides in a drawer or a tray without dividers is the fastest route to chipped corners.
• Handle by the frosted end. It keeps fingerprints and skin oils off the specimen area and off the cover glass.
• Keep the container closed. A lid or door mainly keeps dust off; dust on a cover glass is a nuisance under the objective long before it is anything worse.

Beyond the mechanical basics, how a stained specimen ages depends on the stain, the mountant and the sealing method rather than on the container. Storage conditions for a particular preparation should follow the protocol your lab already uses for it — no cabinet or box, ours included, changes the chemistry.

A collection you cannot search is a collection you will re-cut. Labeling is what makes a slide findable; indexing is what makes it findable quickly.

On the slide

• Write on the frosted end with pencil or a marker rated as solvent-resistant. Ordinary marker ink comes off on contact with xylene and alcohols.
• Record an identifier that ties back to a record elsewhere — accession number, block number, case or experiment ID — rather than a description. Descriptions run out of room and go stale.
• Use one format across the collection. Mixed conventions are the reason people end up hunting tray by tray.

Across the collection

• Fix a location, not just an identifier. Cabinet → tray number → compartment is enough to send someone straight to a slide. Eberbach cabinet trays ship numbered in sets of 25 so this is possible out of the box.
• Keep the index outside the cabinet as well as in it. A spreadsheet or LIMS entry with the location field filled in survives someone reorganizing a shelf. The E2840 3,000-slide cabinet also includes a pullout card-index drawer if you keep a paper record at the cabinet.
• Decide the filing order before the collection is large. Sequential by accession number is the easiest to maintain because new material always goes at the end. Filing by subject or by stain looks tidier and becomes expensive to maintain as soon as you need to insert.

The two have opposite requirements, and most labs are better off separating them than finding one container that half-serves both.

• Active, frequently handled slides want to be near the microscope and quick to open. A small box on the bench is faster than walking to a cabinet, and the handling risk is lower than carrying trays back and forth.
• Retained or reference material wants a fixed, numbered location that does not move. Retrieval is occasional, so a few extra seconds per slide is irrelevant next to knowing exactly where each one is.

In practice this usually means a working set of a few dozen slides in a box, and everything past its active life filed into a cabinet on a regular schedule. The point at which material moves from one to the other is worth writing down.

Three formats cover almost every collection, and the choice is mostly a function of size and how often you move the slides.

• A slide box holds a handful to a few dozen slides and travels. The portable oak microscope slide box (E2000) holds 26 standard slides in solid oak with a foam-padded lid — sized for a teaching set, a field trip or the slides you are actively working through.
• A slide tray is the unit a cabinet is built from: compartmented, removable, and pulled out on its own so the rest of the collection stays put. The E2870 holds 20 slides and is interchangeable across the Eberbach cabinet range, which is also how you add capacity to a cabinet you already own.
• A storage cabinet holds the trays in a fixed, indexed position and scales from 500 to 3,000 slides nominal. This is where a collection ends up once counting boxes has become the problem.

The trade-offs between the three — portability, retrieval speed, indexing, floor space — are compared side by side in the guide to choose a microscope slide storage system.

Buy for the collection you will have, not the one you have. Three numbers are enough to size storage sensibly:

• Current count. Slides already held, including anything currently in drawers and boxes that you intend to consolidate.
• Annual intake. New slides added per year. For a service lab this tracks case volume; for a research group it tracks project count.
• Retention period. How long material stays before it is discarded or moved off site. Current count + (annual intake × retention years) is the figure to size against.

Add headroom on top. A cabinet filled to capacity on delivery leaves nowhere to insert, and inserting is exactly what a sequentially filed collection needs to do. Aim to be somewhere around two-thirds full at installation.

One capacity note specific to compartmented trays: nominal capacity assumes one slide per compartment. Two slides per compartment doubles the figure — an Eberbach cabinet rated at 500 slides will take 1,000 that way. It is a legitimate way to defer a purchase, at the cost of slide-on-slide contact and slower retrieval, so it suits dormant material better than a working collection.

Slides in transit take more knocks in an afternoon than they will in a year on a shelf. For a small set, a rigid box with compartments and a padded lid is the whole answer: the slides cannot slide, and the lid absorbs what the outside of the box takes. That is what the E2000 is built for — teaching sets, site visits, carrying a case between buildings.

Cabinets are not travel cases. Cabinet trays are removable, so the practical approach to moving a large collection is to move it tray by tray, keeping the numbering intact and the trays flat, rather than carrying a loaded cabinet.

As a starting point, matched to the Eberbach range:

• Up to ~26 slides, moving around: a portable wooden microscope slide box.
• A few hundred slides, staying put: the 500-slide E2800 storage cabinet, which stacks and banks with more units as the collection grows.
• One to two thousand slides: the E2820 at 1,000 slides or the E2830 at 2,000, with 50 and 100 numbered trays respectively.
• Three thousand and up: the E2840, with 150 trays and a card-index drawer.
• A cabinet that is full: extra replacement slide trays before a second cabinet.

Full capacities, tray counts and shipping dimensions for every model are listed on the microscope slide storage range.