Reference
Media and what each needs
One row per medium: how sensitive it is to light as published, what harms it, the glazing and mounting it wants, and whether it may touch glazing. Filter it to the rows that match what you have.
Every sensitivity figure here is published for institutional collections on exhibition, by the body named in the row. Where two publishers disagree, the row says so rather than averaging them. Telling them apart is how you work out which rows are yours.
| Medium | Published light sensitivity | What harms it | Glazing and mounting | May it touch glazing? |
|---|---|---|---|---|
| Inkjet print (home or lab) | A national library puts all digital photographic prints including inkjet in its very light sensitive band: maximum 3 footcandles, three to five months, then three years dark | Light, water, abrasion. The enclosure standard that covers modern home prints is the album and framing materials standard rather than the Photographic Activity Test's main method since 2025 | Ultraviolet-filtering glazing; corners or hinges to the back mat | No |
| Offset or screen-printed poster | Treated as paper: a preservation leaflet allows most collection material at 50 to 150 lux for three to four months with no fading expected | Light, acidic board, humidity. Usually replaceable, which changes the package rather than the physics | Any glazing; a mid-grade board is defensible, but not a colored surface paper over a groundwood core | No |
| Watercolor and other works on paper in color | A national library's very light sensitive band: maximum 3 footcandles, three to five months, then three years dark. A museum's duration table puts watercolors in its category B, six months in five years at 50 lux | Light above all. Acidic mats, which leave the brown window line. Humidity, which cockles the sheet if it cannot move | Ultraviolet-filtering glazing; cotton or alpha cellulose board; hinges or corners to the back mat | No |
| Pastel, charcoal, chalk, soft graphite | A museum's category B with watercolors: six months in five years at 50 lux | Anything touching the surface. Static charge on plastic glazing. Vibration and transport | Anti-static acrylic with a spacer, or glass with a spacer. The trade specification asks for at least 5 to 6 mm of space; a professional wiki asks for at least an eight-ply mat's worth. No fixative | No, and further off than usual |
| Pencil and metalpoint drawings | A national library's moderately light sensitive band: 5 to 10 footcandles, six to nine months, then two years dark | Abrasion and smudging; acidic board | Ordinary conservation package; soft graphite is friable and belongs in the row above | No |
| Prints in carbon or earth pigments | A national library's moderately light sensitive band. A museum's category C: twelve months in five years at 50 to 100 lux | The paper rather than the image; a leaflet notes paper itself must be cautiously considered low sensitivity, and its tint is often not | Ordinary conservation package | No |
| Documents and certificates | As paper. Iron gall and purple manuscript inks are in the very light sensitive band; black India ink is moderately sensitive | Light, acid, folds. A federal leaflet asks for buffered or alkaline-reserve material at pH 8 to 8.5 for paper documents | Buffered board; corners or channel supports; glazing to suit | No |
| Black-and-white fiber-base print, traditionally processed | Publishers disagree. A federal leaflet gives 50 to 100 lux for most photographs on exhibit. A conservation institute says well-processed silver gelatin prints on fiber-base paper are essentially stable to light and may be shown for several weeks or a few months at roughly 800 lux, plus or minus 200 | Relative humidity, which a national library calls the single most important factor. Pollutants. Buffered board, in one view | Unbuffered board in the professional wiki's view; board that has passed the Photographic Activity Test; corners rather than plastic ones | No; a conservation institute notes moisture could make the print and the glass stick together without a window mat |
| Resin-coated black-and-white print | A conservation institute excludes resin-coated papers from its 800 lux exemption. A national library puts all silver gelatin prints on resin-coated supports in its very light sensitive band | Light, and the coating itself | As above; it lies flat and feels plastic at the edge, which is how to tell it | No |
| Color photographic print | A national library puts all color photographic processes in its very light sensitive band. A preservation center notes most color photographs fade rather quickly | Light, heat, humidity. Cold storage is what the published guidance asks for | Unbuffered board; corners; ultraviolet-filtering glazing; and seriously consider displaying a copy | No |
| Albumen, salted paper, cyanotype, platinum | A museum's duration table puts albumen, salted paper and cyanotype in its most restrictive photographic category: three months in five years at 50 lux. A conservation institute reports recommended levels for salted paper and albumen varying from 5 lux to 100 | Light; alkalinity for cyanotypes and dye transfer prints | Unbuffered board, required, in the professional wiki's and a conservation center's terms. A professional wiki notes unmounted albumen photographs cannot be safely photocornered because they sag | No |
| Cased photographs: daguerreotype, ambrotype, tintype | A museum's category B: six months in five years at 50 lux, and anything with an exposed dyed leather or textile case element moves to the most restrictive category | Handling, the case itself, humidity | A conservator's subject before a framer's. Do not open a sealed case | Not applicable; they are housed, not framed |
| Oil painting on canvas | A museum's category E: unlimited display at 300 lux, for light-stable pigments. A conservation center's less sensitive band: 150 lux maximum | Humidity swings, puncture from behind, heat, vibration. Direct sun, which a conservation institute calls the single most damaging source of incorrect temperature | Usually no glazing. 3 to 6 mm clearance in the frame on all sides, a padded rabbet, and a backing board, which a conservation institute says all paintings should have | If glazed, no: the institute says glazing must never touch the paint surface and the method must include a spacer |
| Acrylic painting on canvas | As above for light; the paint film behaves differently with temperature | A conservation institute notes acrylic paints enter their glassy phase below 5 degrees Celsius and become more vulnerable to shocks, and that they do not tolerate even mild organic solvents | As above. Do not frame before paint and varnish are fully dry | No |
| Children's art | Treat as the most sensitive thing on it: felt tip pens and most colored pencils are in a national library's very light sensitive band, and most felt tip pens including blacks are high sensitivity in a conservation institute's categories | Light, and the paper, which is usually poor. Often friable in places | An ordinary conservation package is more than most of it needs; a copy on the wall is a legitimate answer. If it is chalk or oil pastel, use the friable row | No |
| Embroidery, needlework, flat textile | A museum's category B: six months in five years at 50 lux. Vegetable-dyed material is in the most sensitive band in a state museum body's fact sheet | Light, dust, humidity, and its own weight if it is not supported. Staples, tacks and adhesives | Stitched by hand to a fabric-covered rigid support, never glued or stapled. Spacers, which a conservation institute says stop the glazing crushing the three-dimensional quality | No, and spacers rather than a mat window pressing into it |
| Objects and memorabilia in a box | By the most sensitive component, per a museum's own rule | Whatever the object is made of, plus the support failing | No household-scale source was found in this research. The trade specification asks for a reversible support with no adhesive or silicone. Treat it as a framer's job and ask how the object is held | Depends on the object; ask |
| Not identified yet | Treat it as the more sensitive of the candidates | Unknown, which is itself a reason to specify upward | The more protective option of the two it might be. An uncertain identification is a reason to spend more, not less | No |
How to read this table
- The sensitivity column names the publisher, not a consensus. Where a row says publishers disagree, both figures are real and they are describing partly different objects.
- Lux figures are for institutional collections on exhibition. They tell you what a wall costs per year, which the exposure box turns into a number for your own wall.
- The last column has only one answer in it. Every publisher in this research says nothing inside the frame may touch the glazing; what varies is how much space, and for friable media it is more than a four-ply mat gives.
- An object's category is set by its most sensitive component. That is a museum's own rule, and it is why a hand-colored photograph is rated as the hand-coloring rather than as the photograph.
Limits
This table summarizes published guidance; it is not a condition assessment and it cannot identify your piece. Where it names a figure it names who published it, and where publishers disagree it shows both. Nothing here says a picture is damaged or safe: it says what the published guidance expects, and Where it can hang is where that meets your own room.