Vellum Grade 4

Vellum Grade 4, formally designated under the Principal Register as Line Sigma-4, is a classification of penitent-grade vellum authorized for specific administrative and remedial tasks within the Tower. It is distinguished by a nominal thickness of 0.12 millimeters and a surface finish characterized as "moderately absorptive."

Specification and Production

The material specifications for Vellum Grade 4 are enumerated in Annex Ω-7 of the Third Concordance, last amended in the Year of the Script 437. The vellum is produced exclusively by the Physickers of the Deep Font from the dermal layers of unspecified penitent-class subjects undergoing sanctioned remediation. The curing process involves immersion in a solution of Archive-Grade Neutral Salts for a period not less than forty-two days, after which it is pressed between sheets of Archive-Grade Buffer 7 until the specified caliper is achieved. The resulting sheet is a pale, uniform grey, exhibiting minimal translucency.

Authorized Uses

Per Ordinance 441.9, Vellum Grade 4 is authorized for the following applications:

• The drafting of preliminary findings during a sanctioned Vellum Descent.
• The creation of duplicate ledgers for volumetric accounting of non-permanent holdings (e.g., Phantom Pollen inventories).
• The recording of procedural minutes for Guilds of Grade V and below, including the Lamplighters Union.
• As a temporary substrate for sigils marked with Luminous Chalk, provided the sigils are erased within one full diurnal cycle of the Tower.

It is explicitly not authorized for the inscription of permanent ordinances, the recording of primary registry entries onto the Master Roll of Primary Registrants, or for any documentation pertaining to the integrity of Nictitating Vellum. The use of Verity Ink on Vellum Grade 4 is prohibited, as the absorptive surface causes unacceptable bleed-through.

Disputes Regarding Classification

The classification of Vellum Grade 4 within the broader schema of archival materials is a point of ongoing scholarly contention. The Second Concordance, Clause XIX, defines it as a "remedial substrate," implying its purpose is pedagogical and transient. However, a contradictory amendment to the Fifth Concordance (Clause VII, sub-clause δ) reclassifies it as a "tertiary archival medium," a status that would permit its use in longer-term storage under controlled conditions. This reclassification was itself referenced—but neither affirmed nor overturned—during the evidentiary review of Vellum Descent Sigma-1. The matter is currently pending review by the Sub-committee on Material Permanence.

Storage and Handling Protocols

Bundles of Vellum Grade 4 are to be stored vertically in acid-free sleeves fabricated from a derivative of Archive-Grade Neutral Substrate. They are housed in climate-controlled stacks on Floors 22, 115, and 419, though not within the specialized buffer-lined chambers reserved for higher-grade materials on the latter floor. Handling requires gloves of undyed linen; the oils from bare skin are known to induce premature calcification at the sheet edges, rendering them brittle. Spoiled or expired sheets are to be returned to the Physickers of the Deep Font for pulping and re-integration into the production cycle.

Distinction from Other Vellums

Vellum Grade 4 occupies a distinct niche between purely utilitarian and truly archival materials. It lacks the self-referential clarity of Vellum of Perpetual Claritude, the reactive properties of Nictitating Vellum, and the temporal instability of Phantom Vellum. It is also distinct from Vellum of Perpetual Reckoning, which is reserved for final accounting judgments. Its most direct comparator is the Sigma-3 grade used in sifting Phantom Pollen; Grade 4 is approximately 0.03 mm thicker and demonstrates marginally greater structural integrity under tension.