Is Wet Plate Collodion Photography “Silver-based”?

What “Silver-Salt Photography” Means in Japanese

In Japanese, we have a special term — “ginen-shashin (銀塩写真) — which literally means “silver-salt photography.”It refers to all analog photographic processes that record images using silver halides — from film photography to the early wet plate collodion method.

Interestingly, this expression doesn’t really exist in English. People usually just say film photography or silver-based photography.But the Japanese term “silver-salt” captures the chemistry behind how light once became an image — long before the digital sensor was born.

In this article, I’d like to explain what “silver-salt” actually means:Why silver? What kind of salt? And how is it related to wet plate photography — the earliest form of silver-based image-making?

What Is “Silver-Salt” Photography? 

“Silver-salt photography” (銀塩写真 / ginen-shashin) means any photographic process that uses silver halides — compounds made of silver (Ag⁺) combined with halogen ions like chlorine (Cl⁻), bromine (Br⁻), or iodine (I⁻).

These halides are light-sensitive. When exposed to light, they undergo a chemical reaction that forms a latent image, which can then be developed into a visible picture.

Both photographic film and photo paper are coated with these silver halides.That’s why they’re sometimes called “silver-based materials.”

What Does “Salt” Mean Here?

In chemistry, a “salt” refers to a compound made by combining a metal ion and a nonmetal ion.

For example, table salt (sodium chloride) is made of sodium (Na⁺) and chlorine (Cl⁻).In photography, instead of sodium, we use silver ions (Ag⁺), which combine with halogen ions (Cl⁻, Br⁻, I⁻) to form silver halides like silver chloride or silver bromide.

That’s why we call it “silver-salt photography” — even though it has nothing to do with the salt on your dinner table.

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A Bit of Photo History: Salt Prints

One of the earliest photographic printing methods — the salt print — literally used this chemistry.Photographers soaked paper in a salt solution, coated it with silver nitrate, and let the two react to form light-sensitive silver chloride.

This technique marked the birth of silver-based printing and set the foundation for later photographic materials.

How Silver-based Photography Works

Exposure (Light Reaction)

When the film or paper is exposed to light, silver halide crystals react and form a latent image that’s invisible to the eye.

Development

During development, chemicals reduce the exposed silver ions into metallic silver, making the image appear.

Fixing

The remaining unexposed silver halides are washed away, leaving behind only the permanent image.

Film Photography and the Role of Silver

In film photography, the negative image is first recorded on film.Then, when that negative is printed onto photo paper, the tones are reversed — producing the positive image we see.

Both the film and the paper rely on the same principle:light changes silver halide into metallic silver, forming areas of density and tone.

It’s this transformation — from invisible silver salts to visible metallic silver — that gives analog photos their depth and warmth.

Wet Plate Collodion — The Earliest Silver-based Process

The wet plate collodion process, invented in the 1850s, is one of the earliest forms of silver-based photography.A glass (or metal) plate is coated with a collodion solution, then sensitized in a silver nitrate bath to form a layer of light-sensitive silver halides.

When exposed and developed while still wet, the image appears as a physical layer of metallic silver on the plate.Because the surface is smooth and rigid, wet plates can capture incredibly fine detail and a distinct metallic presence — qualities that make them unlike any modern medium.

Why Silver?

During the early days of photography, inventors tried many materials — asphalt, iron, even platinum.But silver proved exceptional:it reacts efficiently to light, produces delicate tonal gradations, and remains stable for centuries.

The microscopic silver particles can render the finest transitions from black to white — creating that luminous, almost ethereal beauty unique to silver-based images.

The world’s oldest photograph was made using the light-sensitive nature of asphalt—a technique called heliography.

Cyanotype uses iron salts and is known as the origin of the word “blueprint.”

Later came silver-based photography, which evolved into the wet plate process like ambrotypes, capturing images made of silver on glass or metal.

In the End

“Silver-salt photography” is essentially the art of capturing light through chemistry.Wet plate photography represents one of its earliest — and most tangible — forms.

Even in our digital age, there’s something deeply moving about watching an image appear through light and silver.It reminds us that photography was once not just about capturing reality, but about making matter react — turning light into something you could hold.

If this sparked your curiosity, I encourage you to experience silver-based photography in person.There’s a kind of beauty there that no screen can ever quite reproduce.

Silver-based photography → Wet plate photography (Ambrotype)

If this sparked your curiosity, I hope you’ll see these photographs in person.Their beauty is something you can’t fully feel through a screen.

• 湿板写真の技法について → 湿板写真とは

• 湿板についてもっと知る → 湿板Journal（blog）

• 実際の作品を見る → ギャラリー

• 撮影や体験をしてみたい → 料金／ワークショップ