Luminous Chalk (Grade B)

Luminous Chalk (Grade B) is the ordinary working chalk of the Tower's stores: a self-emitting marking compound issued in boxes of forty-eight sticks, each stick burning with a steady, low, greenish-white light for eleven hours. It is certified by the Directorate of Luminance on Floor 8 the Chalk Halls and is the grade most frequently drawn against requisitions by Wayfinders for temporary sigil-marking on non-material surfaces. It stands between Grade A, reserved to the Office of Luminous Accounting, and the warmer, weaker sticks of Grade D Luminous Chalk issued in the sub-vaults; the family as a whole is described at Luminous Chalk.

Formulation and certification

Each stick measures nine and a half centimetres and is wrapped in unsealed grey paper bearing the batch spiral and the certifying aperture-mark of the Directorate. The compound is a chalk base charged with a suspension whose exact constituents are held under Concordance 9, Annex 2, and may not be copied outside the Directorate's scriptorium. What is published is the performance: eleven hours of emission, a falloff of no more than one part in forty across the working life of the stick, and a residue that may be brushed from any hard surface without leaving a Luminous Signature behind. Sticks that fail the falloff test are not destroyed; they are re-graded to D and sent downward.

The Office of Luminous Accounting maintains that Grade B, Luminous Mortar, and Luminous Verdian share a common charge and differ only in binder, and cites the identical colour temperature of all three in support. The Directorate has never formally disputed this. It has, however, declined four times to countersign the Office's comparison tables, and the omission is noted in every edition of the certification register.

Requisition and the Halden finding

Grade B is drawn by requisition, counted in boxes, and reconciled at the close of each shift. The count is the difficulty. Because the sticks are read by their own light, a storekeeper cannot tell a full box from an empty one without opening it, and the opening consumes the seal. The resulting discrepancies were for a long time entered as wastage.

The practice changed after the submission of Ostrev Halden, a clerk on Floor 331, who in the winter of the year recorded as 4,112 submitted a requisition for two hundred and sixteen boxes — one stick for each unlit alcove on his round, counted once for each hour of his shift. Halden's arithmetic was correct and his need was not. The Adjudication of the Chalk-Dust Hands heard the matter and ruled that a requisition must state the marks intended, not the dark they are intended to relieve; the ruling is now printed on the reverse of every requisition form. Halden was reassigned to the counting of alcoves and given no chalk. His finding stands, and storekeepers still call an inflated draw "counting alcoves."

The Crisis of Recursive Annotations

Grade B's best-known incident occurred on Floor 719, in the garden maintained there, when an archivist correcting an annotation previously laid down in Memoria Chalk worked over the error with Grade B. The two compounds interacted, as the inert Memoria formulation will when brought into contact with an active luminous charge, and the correction did not replace the annotation but produced a second one beside it — a Protocol-Bound Annotation that could not thereafter be lifted, scraped, or argued away. The Crisis of Recursive Annotations occupied the floor for the better part of a season and is treated at its own entry.

The Directorate's position, restated at every recension since, is that Grade B behaved exactly as certified and that the fault lay in the surface. The Wayfinders' position is that a chalk intended for non-material surfaces should not have been within reach of a volume. Neither body has withdrawn its account, and College of Luminous Anomalies now teaches the incident as an example of correct materials in incorrect order.

Comparison with Grade A

The distinction between the two upper grades is a persistent subject of scholarly disagreement. Concordance 9, clause 14, defines Grade A by duration alone — any stick emitting beyond thirty hours — and says nothing of brightness. The Office of Luminous Accounting, in its third recension, defines Grade A by reservation, holding that a grade is A if the Office has reserved it, whatever its emission. A stick may therefore be Grade A under one instrument and Grade B under the other, and several have been, without any party being in the wrong.

"Where two instruments describe one stick, the stick is not thereby two sticks; it is one stick described twice, and the storekeeper is to issue it once."

— Concordance 9, Annex 6

Storekeepers regard Annex 6 as the most useful sentence in the Concordances and the least often cited in disputes.

Handling and storage

Grade B is stored in the Chalk Vault at the temperature of the floor on which it is kept, in boxes stacked no more than six high, on the unlit side of the corridor. Sticks are not to be carried loose in a pocket. A stick that has begun to dim may be finished on any non-material surface for which no record is required, but must not be returned to its box, as the dimming spreads to the sticks it touches and the batch spiral can no longer be read. Wayfinders mark with the stick held at the far end; the near end is left unlit by the grip and is where the batch number is printed.

Boxes recovered from expeditions below Floor 900 have been found to emit after an interval the Directorate's instruments cannot measure, and are held unopened pending a determination. The determination has been pending since 4,109.