Established Eighteen Hundred and Forty-Two

Mathew's Daguerreotype Studio

Portraits in Silver & Light — by Permanent Process
No. 233 Washington Street · Boston
"Your beloved face — held forever in a plate of polished silver."
Wide view of Mathew's portrait studio: large-format camera on tripod, daylight window, mahogany sitting chair, headrest stand, framed silvered plates upon the wall.

Filter the Ledger

Classification
Year
Development

I. Plate Preparation

A copper plate is clad in pure silver and buffed to a true mirror. The polishing is done by hand with rouge powder, then with finest buckskin, until one's own face is returned undistorted from the surface.

Rouge buff — 8 minutes, in three directions
Velvet finish — 4 minutes, single direction
Final breath-test for any clinging mote

II. Iodine Sensitization

The mirrored plate is suspended face-down over an iodine box in the darkened sensitizing room. Vapours rise and form a thin coating of silver iodide. The plate must turn the precise rose-gold tint of a winter sunrise — no darker, no lighter.

Iodine box — 60 to 90 seconds at studio temperature
Bromine accelerator chamber, per Disdéri's rosewood-block technique, 12 seconds
Re-iodine, 8 seconds, to set the bromide

III. Exposure in Camera

The plate is brought, light-tight, to the camera. The subject sits braced in the iron headrest. The cap is lifted from the Voigtländer Petzval lens. The exposure runs from twenty to sixty seconds, depending upon the light at the studio window and the complexion of the sitter.

Bright morning, fair complexion: 22 sec.
Overcast: 38 sec.
Late afternoon, gentleman in dark wool: 54 sec.

IV. Mercury Vapor Development

The exposed plate is held above a small iron pan of warmed mercury at 75° C. The vapours seek out only the exposed silver, depositing in fine grains and bringing the latent image forth as if a face were rising through fog.

Mercury pan — preheated
Plate held face-down, 75 to 90 seconds
Removed at first appearance of the brow and shoulder line

V. Fixing & Gold-Toning

Hyposulphite of soda removes all unexposed silver iodide. The plate is then bathed in gold chloride, which both protects the image and warms the tones from chill grey to that gentle bloom of life. The bath is decisive — under-toning leaves a cold ghost; over-toning yellows the cheek.

Hypo bath — 30 seconds, distilled water rinse
Gold chloride — 45 seconds over spirit lamp
Final wash, four changes of water

VI. Sealing & Casing

The dried plate is bound with cover-glass and brass mat, then pressed into a fitted morocco case lined in plush velvet. Sealed thus, a portrait will hold its silver for a hundred years and more — there is no reason to suppose it will not outlast all of us who made it.

Brass mat, hand-cut to plate size
Bevelled cover-glass, sealed with paper tape
Pressed into morocco case — closed with hook clasp
Close detail: a polished silver daguerreotype plate resting in a velvet-lined morocco case, beside a small amber bottle of chemical solution.

We are pleased to take new sittings. Morning light is finest for fair complexions; late afternoon recommended for gentlemen in dark wool. Please indicate any particular wish for the keepsake.

Your appointment will appear in the Sitting Ledger upon entry. We confirm by post within three days.

Entered into the ledger.