Recommended environmental conditions for museum objects


Introduction

Table 3 is a list of recommended environmental conditions for the storage, display and transport of museum objects. Though it may be difficult for a museum to achieve these 'ideal' standards, the best possible conditions within the limitations should prevail. In all cases, the emphasis should be on achieving stable levels of temperature and relative humidity (RH), minimum light levels and elimination of all UV light. In some instances the maximum light level of 300 lux is reasonably low for the material, however it is rarely necessary to exceed this.

The table is organised by materials (ie wood, clay, metal etc) rather than object type (ie machinery, clothing, book). When using the table in relation to objects made from two or more materials, the recomŽmendations for each material should be checked and the narrowest range of temperature and RH, lowest level of lux and mw/lumen and the shortest display period should be taken as the 'ideal' conditions for the whole object.

For example, if you have you have a metal bicycle with a leather seat, rubber tyres and some plastic components, you would assess the categories in Table 1. In comparing the requirements of each material, you will see that the plastic and rubber components have the narrowest range of tolerance in all categories and hence will dictate the environmental conditions.

Table 1
MaterialTemperatureRelative humidity (RH)Max light (lux)Max UV wm/lumenMax display period per 12 months
Leather20 ± 2°C50 ± 10%50 (dyed)
200 (undyed)
30 (dyed)
80 (undyed)
3 months
6 months
Metals (not specified elsewhere)20 ± 2°C< 35%300unrestrictedunrestricted
Plastic (not specified elsewhere)20 ± 2°C50 ± 10%50 (display)
Nil in storage
30 (display)
Nil in storage
3 months
Rubber (soft)20 ± 2°C50 ± 10%50 (display)
Nil in storage
30 (display)
Nil in storage
3 months

Another example is a painting that may be painted in oil on a gessoed canvas, stretched on a wooden strainer/stretcher with a composition gesso and gilt frame. When assessing the painting by comparing the requirements of each material (Table 2), it will be clear that most of the components have a similar but inconsistent range of tolerance. The lowest tolerance in each section should form the ideal environmental conditions for the whole object.

Table 2
MaterialTemperatureRelative humidity (RH)Max light (lux)Max UV wm/lumenMax display period per 12 months
Canvas 20 ± 2°C50 ± 10%50 303 months
Composition (Compo; as used on frame mouldings)20 ± 2°C50 ± 10%200806 months
Gesso 20 ± 2°C50 ± 10%200806 months
Gold (include leaf & gilt) 20 ± 2°C< 35% 300unrestrictedunrestricted
Oil paint 20 ± 2°C50 ± 10%200806 months
Wood (not specified elsewhere) 20 ± 2°C50 ± 5% 200806 months

Table 3
MaterialTemperatureRelative humidity (RH)Max light (lux)Max UV wm/lumenMax display period per 12 monthsProne to insect &/or mould attackOther Considerations
Acrylic paint20 ± 2°C50 ± 10%200806 monthsIf paint is thin, treat as if watercolour. Paint embrittles with age.
Acrylic plastics (ie perspex)20 ± 2°C50 ± 10%3002009 monthsCertain chemicals may cause crazing.
Alabaster20 ± 2°C50 ± 10%300unrestrictedunrestrictedSoluble in weak acids and prone to attack by organic acid vapours.
Amber20 ± 2°C50 ± 10%300200unrestrictedBrittle: cracks or breaks easily. Soluble in many organic solvents.
Bakelite and Catalin20 ± 2°C50 ± 10%200806 monthsDiscolours with age.
Baleen20 ± 2°C50 ± 10%50303 monthsYes
Bamboo20 ± 2°C50 ± 10%200806 monthsYes
Bark20 ± 2°C50 ± 10%200806 monthsYesHygroscopic - will crack, warp etc in fluctuating RH.
BeadworkYesBeads are constructed from many different materials and should be assessed on a case by case basis.
Bitumen20 ± 2°C50 ± 10%200806 monthsProne to dust and dirt accumulation. Can creep prior to drying (20 yrs) and cracks on drying.
Bone20 ± 2°C45 - 65%200806 monthsYesHygroscopic - will crack, warp etc in fluctuating RH. Prone to staining.
Bone china10-30°C20 - 60%300200unrestrictedRepair materials (adhesives, fillers, paint etc) may require lower light levels and restricted display periods.
Brick20 ± 2°C50 ± 10%300unrestrictedunrestrictedRepair materials (adhesives, fillers, paint etc) may require lower light levels and restricted display periods.
Camphorwood20 ± 2°C50 ± 10%200806 months*YesHygroscopic - will crack, warp etc in fluctuating RH.
* Mature wood is resistant to insect attack.
Cane20 ± 2°C50 ± 10%200806 monthsYesTends to embrittle with age.
Canvas20 ± 2°C50 ± 10%200806 monthsYesCollects dust easily.
Cardboard20 ± 2°C50 ± 10%50303 monthsYesDiscolours and embrittles with age. Most cardboard made post 1850 is inherently acidic.
Cast iron20 ± 2°C<35%300unrestrictedunrestrictedMay have a soft graphitised section which is prone to physical damage. Protective coating system may require lower light levels and restricted display periods.
Casein20 ± 2°C50 ± 10%200806 monthsYesProne to drying (crazing) in RH below that recommended. Wax coating will minimise drying. Discolours and embrittles with age
Cedar (Australian)20 ± 2°C50 ± 5%200806 months*YesHygroscopic - will crack, warp etc in fluctuating RH.
* Mature wood is resistant to insect attack.
Ceramic (not specified elsewhere)10-30°C20 - 60%300200unrestrictedRepair materials (adhesives, fillers, paint etc) may require lower light levels and restricted display periods.
Cellulose acetate and cellulose nitrate films<15°C22 - 35%NilNilNilYesDangerous materials, mav ignite in temperatures above those recommended. Must be stored separately in a ventilated area as materials give off acidic vapours. No display, minimum illumination for the purpose of reproduction. CONTACT NATIONAL FILM & SOUND ARCHIVE.
Cellulose acetate and cellulose nitrate objects<20°C< 40%50303 monthsYesMust be stored separately in a ventilated area as materials give off acidic vapours. Soluble in most solvents.
Charcoal (on a substrate)20 ± 2°C50 ± 10%50303 months
Clay10- 30°C< 40%300200unrestrictedMay disintegrate in water. May contain carbonates which are soluble in weak acids. Repair materials (adhesives, fillers, paint etc) may require lower light levels and restricted display periods.
Coal20 ± 2°C50 ± 10%300unrestrictedunrestricted
Composition (Compo; as used on frame mouldings)20 ± 2°C50 ± 10%200806 monthsEmbrittles and cracks with age.
Copper (brass & bronze)20 ± 2°C< 35%300unrestrictedunrestrictedProne to attack from atmospheric pollutants (hydrogen sulphide, sulphur dioxide & sulphuric acid) >15% RH. Protective coating system may require lower light levels and restricted display periods.
Coral20 ± 2°C50 ± 10%200806 monthsSoluble in weak acids and prone to attack by organic acid vapours. Dyed colours are very prone to fading
Cork20 ± 2°C50 ± 10%200806 months
Crayon (on a substrate)20 ± 2°C50 ± 10%50303 monthsYes
Crystal20 ± 2°C50 ± 10%300unrestrictedunrestricted
Earthenware20 ± 2°C50 ± 10%300200unrestrictedMay contain carbonates which are soluble in weak acids. Repair materials (adhesives, fillers, paint etc) may require lower light levels and restricted display periods.
Enamel20 ± 2°C50 ± 10%3002009 monthsHigh-temperature sensitive: glass and metal expand differently, if heated damage may occur.
Feathers20 ± 2°C50 ± 10%50303 monthsYesMust be careful not to detach combs from each other when handling.
Fibreglass20 ± 2°C50 ± 10%200806 monthsMay discolour and embrittle with age.
Flax20 ± 2°C50 ± 10%50303 monthsYes
Fur20 ± 2°C50 ± 10%50303 monthsYes
Gesso20 ± 2°C50 ± 10%200806 monthsMay be soluble in weak acids and prone to attack by organic acid vapours. May weaken in high RH. Embrittles and cracks with age. May delaminate from substrate.
Glass20 ± 2°C50 ± 10%300unrestrictedunrestrictedLow-silica and high-alkali glasses deteriorate in high RH. Repair materials (adhesives, fillers, paint etc) may require lower light levels and restricted display periods.
Glue (animal)20 ± 2°C50 ± 5%200806 monthsYes
Gold (include leaf & gilt)20 ± 2°C< 35%300200unrestrictedSoft metal, prone to physical damage.
Gouache20 ± 2°C50 ± 5%50303 monthsYesHydrogen sulfide (from atmospheric pollution) causes darkening of lead white. Very susceptible to water damage - colour and surface changes.
Hair20 ± 2°C50 ± 10%50303 monthsYes
Horn20 ± 2°C50 ± 10%200806 monthsYesHygroscopic - will crack, warp etc in fluctuating RH. Thermoplastic - can be reshaped under application of heat and pressure.
Horsehair20 ± 2°C50 ± 10%50303 monthsYes
Ink20± 2°C50 ± 10%50303 months
Iron (alloys)2Q± 2°C< 35%300unrestrictedunrestrictedProtective coating system may require lower light levels and restricted display periods.
Ivory20 ± 2°C50 ± 10%200806 monthsYesHygroscopic - will crack, warp etc in fluctuating RH. Prone to staining.
Lacquer (Oriental)20 ± 2°C50 ± 5%50303 monthsSubstrate can be hygroscopic - will crack, warp etc in fluctuating RH.
Lead20 ± 2°C< 35%300unrestrictedunrestrictedProne to attack from organic acid vapours. Wax coating provides protection from acid attack.
Leather20 ± 2°C50 ± 10%50 (dyed) 200 (undyed)30 (dyed) 80 (undyed)3 months 6 monthsYesOil dressed can sweat if it gets too warm. Vegetable tanned leather is prone to red rot. Hardens with age.
Linoleum20 ± 2°C50 ± 10%200806 months
Marble20 ± 2°C50 ± 10%300unrestrictedunrestrictedSoluble in weak acids and prone to attack by organic acid vapours.
Magnetic tape (audio and video)5 ± 4°C20 ± 10%50 (display) Nil in storage30 (display) Nil in storageuse copies only, no use of master permittedAcclimatise tape prior to playback. For tapes in frequent use, the recommended storage conditions are 1 5 ± 2°C and a maximum of 40 % RH.
Masonite20 ± 2°C50 ± 10%3002009 monthsMay give off formaldehyde which can attack other materials.
Metals (not specified elsewhere)20 ± 2°C< 35%300unrestrictedunrestrictedProtective coating system may require lower light levels and restricted display periods. May be stored with vapour-phase corrosion inhibitors.
Micro forms (fiche and films)<20 °C50 ± 10%5030use copies only, no use of master permitted
Mica20 ± 2°C50 ± 10%300200unrestricted
Mother-of-pearl20 ± 2°C50 ± 10%200806 monthsSoluble in weak acids and prone to attack by organic acid vapours.
Nylon (Polyamide)20 ± 2°C50 ± 10%50 (display) Nil in storage30 (display) Nil in storage3 monthsExposure to light can cause discolouration
Oak20 ± 2°C50 ± 5%200806 monthsYesHygroscopic - will crack, warp etc in fluctuating RH. May give off organic acid vapours which can attack other materials.
Oil paint20 ± 2°C50 ± 10%200806 monthsEmbrittles with age.
Paint20 ± 2°C50 ± 10%200806 monthsEmbrittles with age.
Paper and works on paper20 ± 2°C50 ± 10%50303 monthsYesTends to discolour and embrittle with age. Will cockle (ripple and distort) in high RH.
Papier-mache20 ± 2°C50 ± 10%50303 monthsYes
Pastel20 ± 2°C50 ± 10%50303 monthsDo not touch surface as pastels are generally friable (powdery). Binder will become more fragile with age.
Pearl20 ± 2°C50 ± 10%3002006 monthsYesLong term storage can lead to loss of lustre. Soluble in weak acids and prone to attack by organic acid vapours. Dulled by salt water.
Photographs<20°C50 ± 10%50303 monthsYesWill fade and discolour with age. Very cold and dry storage preferred.
Plaster20± 2°C50 ± 10%300200unrestrictedSoluble in weak acids and prone to attack by organic acid vapours. May weaken in high RH.
Plastic (not specified elsewhere)20 ± 2°C50 ± 10%50 (display), Nil in storage30 (display) Nil in storage3 monthsExposure to light can cause discolouration. Plasticisers can migrate to the surface and contaminate other materials.
Plywood20 ± 2°C50 ± 5%200806 monthsYesHygroscopic - will crack, warp etc in fluctuating RH. May give off formaldehyde which can attack other materials.
Polyethylene and polypropylene20 ± 2°C50 ± 10%50 (display) Nil in storage30 (display) Nil in storage3 monthsProlonged exposure to light causes discolouration and embrittlement. Water resistant.
Polystyrene20 ± 2°C50 ± 10%50 (display) Nil in storage30 (display) Nil in storage3 monthsProlonged exposure to light causes discolouration and embrittlement. Soluble in many solvents: liquids and vapours.
Polyvinyl Chloride (PVC)20 ± 2°C50 ± 10%50 (display) Nil in storage30 (display) Nil in storage3 monthsStore separately in a well ventilated area as PVC may give off hydrogen chloride which can attack other materials and catalyse further deterioration.
Porcelain20 ± 2°C20 - 60%300200unrestrictedRepair materials (adhesives, fillers, paint etc) may require lower light levels and restricted display periods
RopeYesRope may be constructed from many different fibres (organic and synthetic) and should be assessed on a case by case basis.
Rubber (incl. Vulcanite and Ebonite)20 ± 2°C50 ± 10%50 (display) Nil in storage30 (display) Nil in storage3 monthsStore separately in a ventilated area as oxidised material gives off acidic vapours. Contact with metals (especially copper) accelerates oxidation.
Rubber (soft)20 ± 2°C50 ± 10%50 (display) Nil in storage30 (display) Nil in storage3 monthsLoses flexibility and embrittles with age. Prone to attack by ozone. Oxygen-free or low oxygen storage recommended.
Seaweed20 ± 2°C50 ± 10%50303 monthsYes
Seeds20 ± 2°C50 ± 10%200806 monthsYes
Shell20 ± 2°C50 ± 10%200806 monthsSoluble in weak acids and may be affected by organic acid vapours.
Shellac20 ± 2°C50 ± 10%200806 monthsProlonged light exposure causes darkening. Tends to be brittle and damages easily. Distorts in temperatures > 30 °C.
Silver20 ± 2°C< 35%300unrestrictedunrestrictedHydrogen sulphide (from atmospheric pollution) causes tarnish > 15 % RH. Protective coating system may require lower light levels and restricted display periods.
Spermaceti20 ± 2°C50 ± 10%200806 months
Steel20 ± 2°C< 35%300unrestrictedunrestrictedProtective coating system may require lower light levels and restricted display periods.
Stone20 ± 2°C50 ± 10%300unrestrictedunrestrictedSome sandstone is alkaline and hence prone to organic acid attack. Repair materials (adhesives, fillers, paint etc) may require lower light levels and restricted display periods.
Stoneware20 ± 2°C20 - 60%300unrestrictedunrestrictedMay contain carbonates which are soluble in weak acids. Repair materials (adhesives, fillers, paint etc) may require lower light levels and restricted display periods.
Terracotta20 ± 2°C50 ± 5%300unrestrictedunrestrictedMay contain carbonates which are soluble in weak acids. Original material may contain chlorides.
Textiles20 ± 2°C50 ± 5%50303 monthsYesDust and dirt will cause abrasion to fibres.
Tin/Tinplate20 ± 2°C< 35%300unrestrictedunrestricted
Tinsel20 ± 2°C50 ± 10%50303 months
Tortoiseshell20 ± 2°C50 ± 10%200806 monthsYesHygroscopic - will crack, warp etc in fluctuating RH.
Water colour20 ± 2°C50 ± 5%50303 monthsBinder will deteriorate with age and become friable.
Wax20 ± 2°C50 ± 5%200806 monthsYesThermoplastic - may distort in temperatures above those recommended. Tends to embrittle with age. Soluble in many organic solvents.
Wicker20 ± 2°C50 ± 5%200806 monthsYesTends to embrittle with age.
Wood (not specified elsewhere)20 ± 2°C50 ± 5%200806 monthsYesHygroscopic - will crack, warp etc in fluctuating RH.
Wool (felt)20 ± 2°C50 ± 10%50303 monthsYesMay give off organic acid vapours which can attack other materials (especially silver).