Ink Saturation

Ink Saturation is the measure of the quantity of ink carried within a given square inch of vellum, parchment, or archival board, expressed in Certified Archival Ink grains per square inch (gsi) and reckoned, in the case of amended documents, at the moment of the reading rather than the moment of the writing. It is the oldest of the Tower's saturation measures and the only one for which a floor has been named, numbered, and then renamed twice.

The measure is not to be confused with its neighbours. Mnemonic Saturation concerns what a text retains; Resonant Saturation concerns what a subject resonates; Buffer Saturation concerns the load borne by a Thematic Buffer. Ink Saturation concerns only what is physically on the page, and the Division of Calibration has defended this narrowness in writing on eleven occasions.

Origins and the Saturation Floor

Ink Saturation entered the record during the recension of the Second Concordance, when the clerks of the Western Habitation Annex complained that documents returned to them from the eastern scriptoria could no longer be folded without cracking. The Guild of Dormant Scribes replied that cracking was a property of the reader, not the page. The dispute was eventually settled by reference to the Fourth Concordance, which established that ink saturation was to be measured, recorded, and — in the words of Annex 2 — "not thereafter argued about by persons who have not measured it."

Floor 44 (formerly the Floor of Weights, and before that unnamed) was redesignated The Saturation Floor in the winter of the year the eastern stairwell was closed for repairs. It remains the only floor where the ambient ink content of the air is posted daily, at the head of the stair, on a slate. Visitors are asked not to lick the slate.

Measurement

Saturation is read with a Calibrated Blot Gauge, a weighted disc of unsized paper pressed to the page for a count of forty and then weighed against a standard. Readings below 3.0 gsi are described as lean; between 3.0 and 6.5 as settled; above 6.5 as burdened. Documents above 9.0 gsi are transferred to Stacks 11-Gamma, where Protocol Gamma-12 holds the air at 13°C and 22% humidity to slow the migration of ink into the binding.

The relationship between Ink Saturation and the broader Vex Saturation Scale is contested. The Scale's own threshold of 8.4 for registering Mnemonic Saturation was, according to the Division of Calibration, never intended to apply to physical ink at all, a position the Scale's custodians have declined to endorse in writing.

The Body's Objection

Redactive Inking — described by the Division as "amendment by saturation" — has been the principal source of high readings since its introduction. A page amended by Redactive Inking three times will commonly read 7.5 gsi or above; a page amended five times is no longer read, and is filed instead.

The Division has issued printed cards on the subject since the Fifth Concordance, Annex 9:

"The card is to be placed face-down upon the amended page and left there. It is not a note. It is not to be read. If it has been read, it was left face-up, and the clerk should present themselves at the Calibration desk before the end of the shift."

— Division of Calibration, printed card series iii, verso

Clerk Orrin Vasp of the Western Annex, who in the winter of the year the eastern stairwell was closed left forty-one such cards face-up and subsequently presented himself forty-one times, was commended for his diligence and reassigned. His grievance — that the cards could not be told apart from the pages beneath them — is preserved in the annex files and has never been answered.

Disagreement in the Concordances

The Seventh Concordance holds that Ink Saturation is a property of the document and travels with it: a page moved from floor to floor carries its reading unchanged. The Ninth Concordance holds the opposite, that saturation is a property of the shelf, and that a page's reading is therefore whatever the surrounding holdings make it. The two have never been reconciled, and the Librarians have declined to prefer either, on the ground that both are Concordances and neither is more recent in any sense the archive recognises.

In practice most floors observe the Seventh and most scriptoria the Ninth, which is why documents are commonly measured twice: once where they are written and once where they are kept. Where the two readings differ by more than 1.5 gsi, the difference is entered in the Margin Ledger under the heading travel, and no further explanation is required.

Ranking by Argument Weight

Ink Saturation is one of the three inputs to the Materialist Coefficient, alongside vellum density and amendment thickness, by which documents are ranked by argument weight. The inclusion was resisted by the Guild of Dormant Scribes on the ground that a heavily inked argument is not thereby a better one. The Division of Calibration conceded the point in a memorandum of the following spring and did not alter the Coefficient, noting that the Coefficient had never claimed to measure quality.

It is this distinction the Division returns to whenever the subject is raised: Ink Saturation measures the ink. What the ink is doing there is a matter for other offices.