Collecting guides
Matrix Numbers… What the Runout Says, and What It Doesn't
Updated · Published
Read the matrix numbers and other marks near a record’s label, compare pressing candidates, and know when an identification needs more evidence.
In short
- The runout, or dead wax, can hold the matrix number, engineer initials and a plant mark.
- A matrix number printed on the label and one inscribed in the runout are different observations.
- Tilt the record under a lamp to the side and copy both sides exactly.
- A different inscription does not automatically mean a different release.
- Failing to find a match does not establish rarity.
The small writing near a record’s label was put there for the people making it. Collectors arrived later, with lamps.
A matrix number identifies manufacturing parts used to make the record. It often resembles the catalogue number with a side letter or number added. Sometimes it does not. There is no single code that explains every record on your shelf.
First, know where you are looking
The runout, also called the dead wax, is the band between the last music groove and the label. It can contain the matrix number, a mastering engineer’s initials, a plant mark and other symbols. They share the space; they do not all mean the same thing. A CD carries its own marks in the ring around the centre hole, and our guide to buying used CDs explains how to read them.
Some matrix numbers are also printed on the paper label. Note those separately. A label matrix and an inscription in the runout are different observations, even when the characters agree.
Read what is there
Stamped characters tend to look regular; hand-etched ones look like someone wrote them. Record that distinction when it helps separate candidates. It is a clue, not a verdict on its own.
- Hold the record by its edges under a lamp to the side. Slowly tilt it until the marks catch the light.
- Work around the whole band. Numbers and other marks may be far apart.
- Copy both sides exactly, including letters and symbols. Mark uncertain characters as uncertain. A photo or magnifier may help.
- Keep the side and location clear in your notes. Discogs asks for a complete runout string per side, with single spaces between separated groups.
There is no prize for reading it in one glance. Change the angle before deciding a faint character must be an 8.
Use it to separate candidates
Start with the sleeve and label. If two editions still look alike, compare their documented runouts with your copy. Our pressing identification guide walks through those earlier checks.
A different inscription does not automatically mean a different release. Discogs can list several runout variants under one release. Check the whole entry and what the difference represents, rather than treating an extra hyphen as a discovery.
Keep the useful uncertainty
Read both sides. Keep engineer marks separate from your interpretation of the matrix. Do not turn a copyright date, a familiar number or a hopeful guess into proof of an edition.
Sometimes the marks settle it. Sometimes they leave two plausible candidates. Save what you can see and note what would distinguish them. Record by Record can help you organise the collection; the evidence still lives on the record.
Questions
Why does the label's matrix number look shorter than the runout's?
Discogs notes that a matrix number printed on the label often leaves out the stamper version and other details found in the runout. A shorter label number is therefore not a contradiction. Enter the two as separate identifiers, each with its location described, and never trim the runout string to fit the label. The characters the label omits can be the ones that separate your copy from its neighbours.
Can the matrix number tell me the catalogue number?
Often. Discogs gives the pattern ABC-001-A and ABC-001-B for a record whose catalogue number is ABC-001. It accepts a catalogue number worked out this way only with good evidence, for instance when it matches the format the label used on its other releases. That is how some white-label records get tied back to a label. When no catalogue number appears anywhere, the matrix goes in the identifiers instead.
When can a runout difference mean a separate release?
Discogs treats matrix differences between copies of one edition as manufacturing variations, and says major-label releases can carry many of them. The exception is smaller releases and special cases, where a variation can mark a distinct edition. Discogs also allows separate entries for different manufacturers, and some manufacturers can only be told apart from the runout. If you think your copy is one of those cases, ask in the Discogs database forum before submitting.
Where can I get help reading a runout I cannot decode?
Discogs points contributors to its Submission Help Forum for interpreting a specific runout, and to a community-built list of what plant and mastering codes mean. Bring clear photos of both sides, taken at the angle that shows the marks, with your transcription and the label details. Someone who knows that plant may place a symbol you have never seen. Their answer is still an interpretation, so note who suggested it.
Sources
- support.discogs.com/hc/en-us/articles/360004017694-Database-Glossary
- support.discogs.com/hc/en-us/articles/360005006614-Database-Guidelines-4-Label-Catalog-Number
- support.discogs.com/hc/en-us/articles/360005054893-Database-Guidelines-5-Barcodes-Identifiers
- support.discogs.com/hc/en-us/articles/360008602254-How-To-Find-Information-On-A-Vinyl-Record