The library belongs to a small Episcopal parish in the South End of Boston, and it occupies a single room on the second floor of the rectory on West Brookline Street. There are roughly four hundred volumes, almost all of them bound in nineteenth-century leather, and a fair number of them are, in the technical phrase, in active red rot.
Red rot is the powdery decay that affects vegetable-tanned leather produced between approximately 1830 and 1900. The leather of this period was tanned with materials and processes that, while serviceable for the first fifty or sixty years, broke down predictably after that. The result is a binding that crumbles to a fine reddish-brown powder under the lightest touch.
The parish librarian, a retired librarian named Anne Sutterfield who has volunteered at the rectory since 2014, brought the problem to the diocese's attention in 2022. The diocese commissioned a survey from a paper-and-leather conservator in Boston named Eduarda Vellutini, who has spent her career on religious libraries.
Vellutini's survey, completed in early 2023, found that of the four hundred volumes, ninety-two were in advanced red rot, one hundred and seventy were in early-to-moderate red rot, and the remainder were in acceptable condition. The advanced cases were leaving red dust on the shelves, on adjacent books, and on the hands of anyone who touched them.
The first decision in addressing red rot is whether to treat the leather at all. The conservator's instinct, when faced with a deteriorating original binding, is to stabilize rather than to replace. A rebound book has lost its original binding and, with it, a significant part of its history as an object. A book in its original leather, however degraded, retains that history.
But stabilization has its limits. Red rot, once it has progressed past a certain threshold, cannot be reversed. The damage is at the molecular level. The collagen fibers of the leather have been broken into shorter, weaker fragments by acid hydrolysis, and no surface treatment can rebuild them.
What surface treatment can do is consolidate what remains, slow further deterioration, and reduce the powdering. There are four interventions that the current literature supports, and Vellutini was prepared to recommend all four, in stages, across the parish library.
The first is environmental. Red rot accelerates in warm, humid conditions and is further driven by atmospheric sulfur compounds, which in a city like Boston come from traffic exhaust and from industrial sources to the south. The library was kept at 72 degrees Fahrenheit year-round and at relative humidities that swung from 28 percent in winter to 65 percent in summer.
The diocese installed a small dedicated HVAC unit in late 2023, which now holds the room at 65 degrees and between 42 and 48 percent humidity. The unit includes activated-carbon filtration on the intake to remove sulfur compounds. Cost: about $14,000 installed, plus modest running costs. The single most important intervention, in Vellutini's view, and the one that most parishes do not make.
The second is housing. Each volume in advanced red rot was measured, and a custom phase box was constructed of acid-free corrugated board. The boxes contain the powder, protect the volume from handling, and provide a stable microenvironment that buffers brief excursions in the room's humidity. The box-making, done by a binder in Cambridge over six months, came to about $9 per volume.
The third is surface consolidation. For volumes still in use — and a parish library is by definition in use — Vellutini recommended a treatment with a dilute solution of Klucel-G, a hydroxypropyl cellulose, in isopropanol. The solution is brushed onto the leather with a soft sable brush, allowed to penetrate, and then allowed to dry.
Klucel-G is the current standard for red-rot consolidation. It strengthens the leather surface, dramatically reduces powdering, and is reversible — a future conservator can remove it with the same solvent. It does not restore strength to the underlying degraded leather, but it stabilizes the surface for routine handling.
Vellutini treated thirty of the parish's most-used volumes herself in early 2024. The treatment takes about twenty minutes per volume and must be repeated every fifteen to twenty years. Cost, at her institutional rate, was about $40 per volume.
The fourth intervention is rebacking. For volumes whose spines have entirely failed but whose boards and textblocks are sound, a conservator can replace the spine leather with new, properly tanned leather that is toned to match the original. The original board leather is retained, and the new spine is applied beneath and around it.
Rebacking is expensive — typically $300 to $800 per volume, depending on size and complexity — and the parish has done only six volumes so far, the ones in active liturgical use. The other advanced cases sit in their phase boxes, consulted carefully when they are needed, and otherwise left undisturbed.
What the parish did not do, on Vellutini's strong recommendation, was apply leather dressings of the kind sold in hardware stores under names like neat's-foot oil, lanolin paste, or leather conditioner. These products were standard practice in librarianship through the 1970s and have been quietly disavowed by the conservation community for the past forty years.
Oils and waxes applied to red-rotted leather do not consolidate the structure. They darken the surface, attract dust, can migrate into the paper of the textblock, and accelerate certain chemical reactions in the leather itself. The shelves of older private libraries are still littered with volumes that were lovingly oiled in 1965 and are, today, in worse condition than untreated volumes from the same shelf.
The single most useful thing an owner of leather-bound books can do, Vellutini said when I sat with her in the rectory library in mid-April, is to do less. Stable cool dry conditions, soft handling, clean shelves, well-made boxes for the fragile volumes, and a willingness to leave the leather alone unless a trained conservator has recommended otherwise.
The rectory library is quieter than it was. The shelves are dusted twice a year with a soft brush attached to a HEPA-vacuum nozzle. The red dust no longer accumulates on the floor. The volumes still smell, faintly, of old leather, which is the smell of slowly breaking collagen and which, for the moment, has been slowed.
Sutterfield brings down the parish's 1872 altar book on Sunday mornings for the eight o'clock service, returns it to its phase box by noon, and notes the loan in a small ledger she keeps at the rectory desk. The book has perhaps another forty years of careful use in it. After that, the parish will need to make a different decision.
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