Caring for prints in a humid climate
Most of the damage this site repairs started in a cupboard. Brown spots, mould, fading, a silvery sheen in the shadows and prints stuck together are all made worse by heat and damp, and much of India spends months of every year in both. A few changes to how prints are kept slow that down, and a scan made now keeps the picture whatever happens to the paper.
What conservators recommend
Conservation guidance from the Northeast Document Conservation Center (NEDCC), a long-standing American conservation laboratory, recommends keeping mixed photograph collections at 30 to 50 per cent relative humidity, with daily swings of less than 10 per cent. The same guidance notes that the chemical deterioration of most photographic materials roughly doubles with every 10°F (about 5.5°C) rise in temperature, and ties high humidity to fading, discoloration and silver mirroring, and, together with heat, to mould growth.
Those numbers are written for archives with climate control. At home the aim is simpler: cooler is better, drier is better, and steady is better than either.
What that means at home
- Keep albums and boxes in an inside room, off the floor and away from outside walls, bathrooms, kitchens and roofs that heat up in the sun.
- Avoid sealed plastic bags and airtight steel trunks for prints that may already be damp: trapped moisture is how mould starts. Breathable archival boxes and sleeves are safer.
- Silica gel in a closed box helps in the monsoon, but it saturates. Replace or dry it regularly, and keep it out of contact with the prints.
- Do not glue prints into old magnetic albums, and take them out of any whose pages have yellowed. Their adhesive stains and can weld a print to the page.
- If prints get wet, separate them while still damp if they come apart easily, and dry them face up on clean blotting paper, out of the sun. If they will not separate, stop and ask a conservator.
Scan before the monsoon
A scan does not stop a print from ageing, but it fixes the picture as it is today. Foxing spots and mould grow; a scan made this year has fewer of them to repair than one made after the next wet season. Scan at 600 dpi, keep the files in two places, and the print becomes a keepsake rather than the only copy.
Damage that has already happened is what the repair routes here are for: brown foxing spots, water stains and tide lines, and fading. Silvering is the exception. It sits on the surface of the print, so scanning with the print slightly tilted helps more than any repair afterwards.
Where to go next
- Remove foxing and mould spotsA detector for brown spots two to forty pixels across, proposed on the mask for you to check before anything is filled.
- Repair a water damaged photoPaint the stain and match it to the picture around it: local light plus a local colour correction, feathered.
- Scanning a damaged print so it can be repairedResolution, bit depth, glass, and why 1200 dpi is refused here.
