A properly built shadow box will outlive you. The same box hung above a radiator in a south-facing window will be visibly degraded in five years. Nothing about the object changes between those two outcomes — only where it hangs and whether anybody ever looks at the back of it.
What follows is museum conservation practice translated for an ordinary house. National Museums Scotland's guidance for entomology collections gives the target conditions as 20 °C and 50% (±5%) relative humidity, in sealed cabinets, kept dark. You are not running a museum and your piece is meant to be looked at. But knowing what the ideal is tells you which compromises are cheap and which are expensive.
Light: the damage you cannot undo
Light damage is cumulative, irreversible, and driven by both intensity and duration. Ten years at low light does the same work as one year at high light. There is no recovery phase and no restoration option — faded scales cannot be re-pigmented.
| Position | Typical lux | Verdict |
|---|---|---|
| Direct summer sun through glass | 10,000–50,000+ | Catastrophic. Visible fading within one season. |
| Bright north-facing room, near window | 1,000–3,000 | Too high for permanent display. |
| Interior wall, daylit room | 150–400 | Acceptable with UV-filtering glazing. |
| Hallway or landing, artificial light | 50–150 | Ideal. |
| Focused halogen spot at close range | 2,000+ & heat | Avoid entirely — the heat is a second problem. |
Practical rules
- Never in direct sun. Not "not much sun". None. Track where the sun actually falls across a full day and across seasons — a wall that is shaded in December can take two hours of direct light in June.
- UV-filtering glazing does most of the work. Good UV acrylic blocks around 98% of ultraviolet. It does not stop visible-light fading, but it removes the most energetic part of the problem.
- LEDs, not halogen. LEDs emit almost no UV and very little infrared. A halogen spot delivers both plus enough heat at close range to warm the inside of a sealed box.
- Rotate long-term pieces. If you own several, swap them between bright and dim positions annually. Museums do exactly this and call it a display rotation.
What fades and what does not
Pigmentary colour fades: reds and yellows first, then oranges, then browns. Structural colour — the iridescent blues, greens and violets — does not fade at all, because it is produced by the physical shape of the scale rather than by any dye. A piece built around structural colour is intrinsically more durable. See Reading a Wing.
Humidity and temperature
The target is 45–55% RH and 18–22 °C. Stability matters more than hitting the numbers exactly: a box held steadily at 60% will fare better than one that swings between 35% and 65% every week, because it is the cycling that does mechanical damage as materials expand and contract at different rates.
| Condition | Effect |
|---|---|
| Above ~65% RH, sustained | Mould on specimen and flora; adhesives soften; verdigris on pins accelerates |
| Below ~35% RH, sustained | Extreme brittleness; flora shatters; backing boards cup and warp |
| Rapid cycling | Condensation on the inside of the glazing; joints work loose; seals fail |
| Above ~25 °C | Pest activity and reproduction accelerate sharply |
Places not to hang it
- Bathrooms and kitchens. Humidity spikes to saturation several times a day.
- Directly above a radiator. A hot rising column plus a daily humidity swing.
- External walls in older buildings. Cold surface, condensation behind the frame. If unavoidable, use spacer bumpers at the corners so air can circulate behind.
- Unheated lofts, garages, basements, garden rooms. Uncontrolled everything.
An inexpensive digital hygrometer on the same wall, watched for a fortnight, will tell you more about a position than any amount of guessing.
Pests: the genuine threat
Light fades. Humidity warps. Pests eat, and by the time you notice, the damage is done. A dried insect is concentrated keratin and protein, which is to say it is food, and there is a small guild of beetles and moths that specialises in precisely this material.
| Pest | Recognise it by | Damage |
|---|---|---|
| Varied carpet beetle (Anthrenus verbasci) | 2–3 mm mottled adult; hairy bristled larva ("woolly bear") | Larvae hollow the abdomen and thorax from inside |
| Museum beetle (Anthrenus museorum) | Similar, slightly smaller | As above; named for a reason |
| Larder beetle (Dermestes lardarius) | 7–9 mm, dark with a pale band | Rapid, gross destruction of soft tissue |
| Booklice (Liposcelis) | <1 mm, pale, fast-moving | Grazes surface mould — their presence signals damp |
| Webbing clothes moth (Tineola bisselliella) | Small gold moth; silk tubes | Larvae eat scales and body tissue |
Warning signs, in order of appearance
- Frass. Fine powder — like ground pepper or sawdust — accumulating beneath the specimen. This is the earliest and most reliable sign. Check it at every inspection.
- Cast skins. Translucent, bristly larval shed skins in the corners of the box.
- Holes and notches in the abdomen or at the wing bases.
- A collapsing abdomen that was previously full.
- Live larvae. At this point you have an active infestation.
If you find an infestation
The standard museum response is freezing, and it works. Do it properly:
- Isolate immediately. Seal the piece in a polythene bag and get it away from every other specimen in the house. Carpet beetles will move.
- Freeze at −30 °C for 72 hours if you have access to a chest freezer that cold. A domestic freezer at −18 °C works but needs at least 7 days, and 14 is safer — some eggs survive shorter exposures at the warmer temperature.
- Thaw sealed. Leave the bag closed and let the whole thing return to room temperature over 24 hours. Opening it cold guarantees condensation directly onto the specimen.
- Clean and reseal the box, removing all frass and cast skins.
- Repeat the freeze after 3–4 weeks to catch anything that survived as an egg.
- Check every other piece you own. Assume it spread until you have evidence otherwise.
Do not use mothballs
Naphthalene and paradichlorobenzene are no longer recommended for collections. They are a health hazard in enclosed domestic spaces, they can react with adhesives and plastics, and they do not reliably kill eggs. Freezing is safer, cheaper and more effective.
A maintenance routine
Every three months — five minutes
- Look at the base of the box under a strong raking light. Any powder?
- Check the inside of the glazing for haze or droplets.
- Dust the outside with a dry microfibre cloth. Never spray anything at the frame — liquid wicks under the glazing edge and there is no way to get it back out.
Every year — twenty minutes
- Lift the piece off the wall and examine the back seal for lifted corners or punctures. Re-tape anything questionable.
- Inspect the specimen closely, ideally with a loupe: abdomen intact, no new notches, pin clean.
- Check hanging hardware — wire fatigue, loose D-rings, tired wall fixings.
- Note the reading on a hygrometer left on that wall for a week.
Never
- Open a sealed box out of curiosity. The seal is the protection.
- Clean the inside of the glazing yourself. If it is hazed internally, something needs diagnosing, not wiping.
- Touch a specimen with bare hands. Skin oils are hygroscopic and scales come away on contact.
- Store a piece flat, face up, for long periods. Anything that works loose settles onto the wings.
Moving and storing
Most damage I am asked to repair happened in transit rather than on a wall.
Carry vertically. Held flat, a loose pin or a detached flower falls onto the specimen. Held upright, it falls harmlessly to the bottom edge.
Pack in the same orientation. Glazing face out, wrapped in acid-free tissue, then bubble wrap, in a box with a minimum of 50 mm of crush space on every side. Mark the outer box this way up and mean it.
Let it acclimatise. A piece that has spent a day in a cold delivery van should stay wrapped for several hours after it comes indoors. Unwrapping a cold box into a warm room condenses moisture straight onto the glazing and, worse, inside it.
Store upright, off the floor, in the dark — in a room you would be comfortable sleeping in. If a space is too damp, too cold or too hot for you, it is too damp, too cold or too hot for the box.
Hang it out of the sun, keep the room boringly stable, and look at the bottom of the box four times a year. That is genuinely the whole of it. Studio notes
Anything that does go wrong, write to the studio. Pieces made here can nearly always be reopened, treated and resealed — get in touch and send photographs.
