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What went wrong?

My platinum or palladium prints look grainy, speckled, blotchy or bleed

Alternative processes

What you're seeing

Mottled or grainy tone following the paper fibres, bright specks, blotchy patches, yellowish highlights, or dark density spreading into a pale sky.

Check this first

Check this first

Check the humidity where you coat and print, and whether the coating was fully dry. Mike Ware finds the best results between 50% and 80% relative humidity.

Likely causes, most common first

  1. 01

    Coating not fully dry before exposure

    Common
    How to tell
    Splotchy areas, often where the coating was heaviest. Bostick & Sullivan say areas not completely dry before exposure print splotchy.
    Test it
    Coat two sheets, dry one for your usual time and the other fully (Mike Ware: about ten minutes at 40°C or an hour at room temperature), and print both.
    The fix
    Let the sensitiser soak in until the surface is no longer shiny, then dry fully in the dark.

    Sources Bostick & Sullivan, Platinum and Palladium Printing Instructions; Mike Ware, Siderotype Workshop Notes: Platino-palladiotype

  2. 02

    Humidity too low or too high

    Common
    How to tell
    In a dry room, paper soaks up too much sensitiser and coats unevenly. Over-humidified paper gives weaker images, clearing problems and, Mike Ware warns, an irremovable yellow iron stain.
    Test it
    Put a hygrometer by the coating area and log the reading with each print.
    The fix
    Keep the paper and room in Mike Ware's 50-80% range. He describes humidifying boxes over saturated salt solutions (common salt gives about 76%).

    Sources Mike Ware, Siderotype Workshop Notes: Platino-palladiotype; Mike Ware, The Platino-Palladiotype Process

  3. 03

    Incomplete clearing

    Common
    How to tell
    Yellowish highlights or margins, easiest to see under bluish light.
    Test it
    Compare the masked coated margin with bare paper after processing.
    The fix
    Extend the clearing baths or make them stronger. Bostick & Sullivan note hard water can slow clearing. Mike Ware prolongs the final EDTA bath.

    Sources Bostick & Sullivan, Platinum and Palladium Printing Instructions; Mike Ware, Siderotype Workshop Notes: Platino-palladiotype

  4. 04

    Unsuitable paper (gelatin size or alkaline buffer)

    Occasional
    How to tell
    Pure platinum prints lose highlight detail first, and grain follows the paper fibres. Mike Ware: gelatin size inhibits platinum, and the paper must be free of alkaline buffer.
    Test it
    Coat the same sensitiser on two papers and print side by side.
    The fix
    Use an unbuffered paper without gelatin size. For grain in pure platinum, Mike Ware suggests the stronger potassium oxalate developer as the first bath.

    Sources Mike Ware, Siderotype Workshop Notes: Platino-palladiotype; Mike Ware, The Platino-Palladiotype Process

  5. 05

    Crystals on the dried sheet

    Occasional
    How to tell
    Bright specks. Mike Ware says crystals show as points of reflected light on the dry sheet, more likely when coating in a cold room.
    Test it
    Inspect the coated sheet under raking light before exposure.
    The fix
    Dissolve crystals in the sensitiser with a drop or two of warm distilled water before coating.

    Sources Mike Ware, The Platino-Palladiotype Process; Mike Ware, Siderotype Workshop Notes: Platino-palladiotype

  6. 06

    Heavily exposed, unmasked border bleeding

    Occasional
    How to tell
    Dark haze spreading inward from the edges into pale areas such as sky. Mike Ware says a heavily exposed border of sensitiser can 'bleed' during wet processing.
    Test it
    Mask the coated margin on the next print and compare.
    The fix
    Mask the margins with Rubylith or black polythene.

    Source Mike Ware, Siderotype Workshop Notes: Platino-palladiotype

Avoiding it next time

  • Coat and print between 50% and 80% relative humidity.
  • Dry the coating fully in the dark.
  • Mask the margins and check them for clearing.

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