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What went wrong?

My salt or albumen prints are blotchy, spotty or uneven

Alternative processes

What you're seeing

Light blotches in dense areas (old manuals call them 'measles'), round white spots, light brown spots, streaks or patches of uneven density, or an overall grey, flat image.

Check this first

Check this first

Look at the shape of the marks. Hard-edged round white spots point to air bubbles at sensitising; soft light blotches in the shadows point to weak sensitising.

Likely causes, most common first

  1. 01

    Weak sensitising ('measles')

    Common
    How to tell
    Blotches or light spots in dense areas. James Reilly links them to a silver solution that is too weak or too little sensitiser left in the paper.
    Test it
    Sensitise a test sheet twice, as Reilly suggests when shadow density is lacking. If the blotches go, the first coat was too weak.
    The fix
    Replenish the silver bath and make it with distilled water: Reilly notes tap water reacts with silver nitrate and robs the bath of strength.

    Source James M. Reilly, The Albumen & Salted Paper Book, ch. 6: Sensitization

  2. 02

    Air bubbles when floating

    Common
    How to tell
    Paper-white round spots with hard edges mean bubbles under the sheet on the silver bath. Light brown spots mean bubbles kept the salting solution off that area.
    Test it
    Lift a corner partway through floating and look for trapped bubbles.
    The fix
    Check for and break bubbles each time you float a sheet. Reilly notes floating nearly always traps a line of bubbles.

    Sources James M. Reilly, The Albumen & Salted Paper Book, ch. 6: Sensitization; James M. Reilly, The Albumen & Salted Paper Book, ch. 3: Salted Papers

  3. 03

    Silver solution on the back, or uneven brushing

    Occasional
    How to tell
    Blotchy patches of uneven density, or streaks following the brush.
    Test it
    Check the back of the sheet for wet patches straight after sensitising.
    The fix
    Keep solution off the back of the sheet, and blot drops from the lower corner while drying, as Reilly advises.

    Sources James M. Reilly, The Albumen & Salted Paper Book, ch. 3: Salted Papers; James M. Reilly, The Albumen & Salted Paper Book, ch. 6: Sensitization

  4. 04

    Porous paper or floating too long

    Occasional
    How to tell
    The whole print is grey and flat rather than blotchy. Reilly: too long on the silver bath gives grey, flat prints, especially on porous papers.
    Test it
    Print the same negative on a harder, less porous paper with a shorter float.
    The fix
    Use a less porous paper and keep floating times short.

    Source James M. Reilly, The Albumen & Salted Paper Book, ch. 3: Salted Papers

  5. 05

    Sensitised paper kept too long

    Occasional
    How to tell
    Yellowish whites. Reilly says sensitised paper keeps only one or two days and may yellow in 8 to 12 hours when warm and humid.
    Test it
    Print on freshly sensitised paper alongside an older sheet.
    The fix
    Sensitise only what you will print that day.

    Sources James M. Reilly, The Albumen & Salted Paper Book, ch. 3: Salted Papers; James M. Reilly, The Albumen & Salted Paper Book, ch. 6: Sensitization

Avoiding it next time

  • Make the silver bath with distilled water and keep it up to strength.
  • Check for bubbles every time you float a sheet.
  • Fix in two baths and do not overwork the fixer: Reilly suggests no more than 10 to 15 prints per litre.

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