Skip to main content

What went wrong?

My cyanotype has white spots, blue specks or streaks

Alternative processes

What you're seeing

White dots or patches, fern-like white patterns, dark blue specks, or brush streaks running through the blue.

Check this first

Check this first

Look at the dry coated paper under a raking light before you expose it. Crystals, puddles or blue specks you can see there will print.

Likely causes, most common first

  1. 01

    Excess sensitiser crystallising

    Common
    How to tell
    White patches or fern-like patterns where the coating was heaviest. Sarah Van Keuren describes orange crystals of potassium ferricyanide forming as puddles dry.
    Test it
    Inspect the coated sheet under raking light for glinting crystals before exposure.
    The fix
    Coat thinly (Mike Ware uses about 1.5 cc for a 10x8in area with a rod) and blot off any excess.

    Sources AlternativePhotography.com (Sarah van Keuren), A Non-Silver Manual: Cyanotype; Mike Ware, Siderotype Workshop Notes: Simple Cyanotype; Mike Ware, The New Cyanotype Process

  2. 02

    Decomposed sensitiser

    Common
    How to tell
    Dark blue specks scattered over the print, including the highlights. Mike Ware: a working sensitiser that turns from yellow to dark blue is precipitating Prussian blue, which causes blue speckles.
    Test it
    Filter the sensitiser, or mix fresh, and coat a second sheet.
    The fix
    Mix working sensitiser only when needed. Mike Ware says filtering can sometimes rescue a solution that has turned.

    Source Mike Ware, Siderotype Workshop Notes: Simple Cyanotype

  3. 03

    Wet or careless brushing

    Occasional
    How to tell
    Streaks that follow the brush direction, or a 'snowstorm' of white dots.
    Test it
    Coat one sheet with a dry brush in slow even strokes, or a coating rod, and compare.
    The fix
    Use a dry brush or rod. Malin Fabbri brushes vertically then horizontally in slow, even strokes.

    Sources AlternativePhotography.com (Sarah van Keuren), A Non-Silver Manual: Cyanotype; AlternativePhotography.com (Malin Fabbri), Cyanotype

Avoiding it next time

  • Coat thinly and blot excess sensitiser.
  • Check coated paper under raking light before printing.

Go deeper