1. Collection Care:
Environmental Factors
Valinda S. Carroll

2. Agents of Deterioration
 High
Temperature
 Humidity
 Light
 Pests and Fungi
 Handling
 Air Pollution

3. Temperature and Humidity
Traditionally, museum climate control
has been based on human comfort, the
capacity of the heating and air
conditioning system, and the limitations
of the building.

4. High Temperature
High temperatures may  Causes cross-linking
damage artifacts in (makes materials become
several ways brittle)
 Causes chain scission
(makes materials weaker)
 Makes materials expand
(causes splitting and
delamination)
 Lowers relative humidity
(causes shrinkage and
splitting)

5. High Humidity
Excessive humidity is  Accelerates chemical
damaging to art and damage
historic artifacts  Promotes swelling,
distortions, and
delamination
 Encourages mold growth
 Increases insect activity
(especially combined with
high temperature)
Warped floor tiles

6. Measurement Tools
 Handheld  Recording
Thermohygrometer Hygrothermograph
 Thermometer and  Electronic Data loggers
Psychrometer  Temperature and
Humidity Indicator
Cards

7. Handheld
Thermohygrometer
Advantages
•Displays relative humidity
•Displays temperature
•Portable
•Easy to use
•Does not require additional
equipment or supplies
•Inexpensive

8. Handheld
Thermohygrometer
Disadvantages
•Does not record over
time
•Does not store readings
•May be inaccurate, and
difficult to calibrate
•User must purchase
batteries

9. Aspirating Psychrometer
•Compares wet bulb
and dry bulb
temperature to find
dew point and relative
humidity
•Contains light to
make thermometers
easier to read

10. Aspirating Psychrometer
 Uses a fan to evaporate
moisture from cloth on wet
bulb
 Can assist in calibrating
Wet bulb other instruments
 More reliable and easier to
use than sling
psychrometer

11. Aspirating Psychrometer
• Does not record over
time
• Requires slide rule or
mathematical
calculations
• Does not generate
documentation

12. Recording Hygrothermograph

13. Recording hygrothermograph
Advantages
•Shows temperature
Red
temperature
line

14. Recording hygrothermograph
Advantages
•Shows temperature
•Shows humidity
Blue humidity
line

15. Data logger
Advantages  Records over time
 Small enough to fit into
exhibit case or packing
crate
 Data can be loaded into
standard spreadsheet
software to generate
reports
 May be less expensive
than hygrothermograph

16. Data logger
Disadvantages
 Requires batteries
 Inexpensive models
cannot be read without
computer
 Inexpensive models
must be downloaded
individually, by hand

17. Humidity Card
Advantages
• Small enough to fit into frame,
exhibit case, or shipping crate
•Inexpensive unit cost
•Does not require batteries
•Does not require computer or
slide rule

18. Humidity Card
Disadvantages
• Imprecise
•Not durable
•Does not record over time
•Cobalt blue salt is toxic (orange
humidity cards are non-toxic)

19. Temperature Card
Advantages
•Inexpensive
•Easy to use
•Portable
•Small enough to fit into frame,
exhibit case, or shipping crate

20. Temperature Card
Disadvantages
•Imprecise
•Does not record over time
•Does not generate permanent
documentation
•Not durable

21. Effects of Light
Light is necessary for exhibits, but excess
exposure can lead to many problems
 Fading
 Yellowing
 Weakening and breakage of fibers and
polymers

22. Light Monitoring Tools
 Blue Wool standard
 Light meter
 UV meter
 Light data logger

23. Blue wool
Advantages
•Blue wool swatches provide a qualitative
assessment of fading.
•They are compact and portable enough to use in
frames or exhibit cases.
•A spectrophotometer or colorimeter may be used
to detect blue dye fading before it becomes visible
to the human eye.

24. Blue wool
Disadvantages
•Blue wool standard swatches only show
fading; they cannot indicate future fading or
other types of damage.
•The extent and rate of fading vary depending
on the spectrum of the light source. Blue wool
standards were designed for use with sunlight,
not artificial lights.

25. Light Meter
Advantages
•Can measure output from
windows and lamps
•Can measure incident
light falling on surface of
object
•Portable
•Can be read instantly
•Can show lux or foot-
candles
(1 foot-candle~ 10 lux)

26. Light Meter
Disadvantages
•Does not generate
permanent record
•Requires batteries

27. Ultraviolet Meter
Ultraviolet radiation is expressed relative to the overall light level in
lux. The maximum recommended amount of UV is 0.375
microwatts per square centimeter, measured at a light level of 50
lux (about 5 foot-candles).
Ultraviolet (UV) meter
showing 9 microwatts per
square centimeter, a rather
high level.

28. UV-filtering materials
Ultraviolet filtering materials
can be used in windows, light
fixtures, exhibit cases, and/or
frames
•Acrylic (Plexiglas UF, Acrylite
OP, TrueVue Optium)
•Polycarbonate (Lexan)
•Laminated Glass (Schott
Amiran)
•Filtering window films
•Fluorescent tube sleeves

29. Mitigation Strategies
 Store collections in closed boxes and
cabinets, rather than open shelves
 Close shutters (in historic buildings),
shades, or blinds
 Use UV-filtering glazing in frames
and exhibit cases and UV-filtering
sleeves on lights
 Hang curtains in front of vulnerable
artwork or drape cloth over exhibit
cases when museum is closed
 Use motion detector switches for
gallery lighting

30. Biological Agents
 Fungi
 Insects
 Rodents

31. Mold Safety
 Always wear personal protective
equipment: N95 respirator, gloves,
goggles
 Use a HEPA vacuum and a soft brush
( a HEPA or ULPA filter prevents the
vacuum cleaner from filling the air
with microscopic mold spores)
 Create a work area separate from
collections storage to avoid cross-
contamination

32. Insects
 Many insects are
attracted to food  Some insects eat only
eaten by humans one type of material, so
 Insects seek shelter it is useful to consult an
in human identification chart
habitations,
especially during
inclement weather
 Many insects feed on
starches and
proteins in museum
artifacts

33. Rodents
 Rodents are attracted
to food eaten by
humans
 Rodents seek shelter in
human habitations,
especially during
inclement weather
 Rodents feed on
starches and proteins
in museum artifacts

34. Pest Control Methods
 Seal entry points (caulk,
weather-strip, etc.)
 Remove food sources and
breeding places
 Use outdoor bait stations
to control rodents before
they enter the building
 Monitor insect activity
with sticky traps and
pheromone lures

35. Pest Control Methods
 Lower temperatures,
possibly to freezing point
 Reduce relative humidity
 Remove sources of oxygen
(nitrogen or argon chamber,
Ageless™ oxygen absorber)

36. Air Pollutants
 Soot and smoke
 Outdoor pollutants
 Volatile organic compounds
 Off-gassing from collections and exhibit
materials
 Ozone

37. Open Flames
•Candles generate soot
•Flames in generate
very high heat
•Genuine candles,
working fireplaces, and
cigarette smoking may
lead to fires
Use electric or battery-operated candles and fireplace inserts to
avoid unnecessary risks to your collection

38. Outdoor Pollutants
 Car exhaust
 Factories
 Forest fires

39. Outdoor Pollutants
 Keep windows and doors
closed
 Change filters in HVAC
system
 Store artifacts in protective
enclosures

40. Volatile Organic Compounds
Regular Paint Low VOC Paint

41. Off-gassing
Protect artifacts from
contact with materials  Unstable plastics
known to release harmful (cellulose acetate,
gasses cellulose nitrate, etc.)
 Unsealed wood
(interior grade
plywood, oak, etc.)
 Paints or cleaning
materials of unknown
or untested
composition

42. Volatile acetic acid
(cellulose acetate film deterioration)
moderate
severe
severe
slight
Controls

43. Oddy Test

44. Hidden dangers
Ozone
Photocopiers and laser
printers emit ozone. Keep
such machines in office
spaces separate from
from collections storage
areas.

45. Protective Housing Materials
 Absorb or adsorb
chemical pollutants
from the air
 Thin sheets can be
incorporated into
frames and exhibit
cases
 May act as mechanical
barriers to pollutants Plastic films and bags with
 Easy to use Intercept ™ technology (finely
divided copper)

46. Protective Housing Materials
 Microchamber ™ paper
 Bainbridge Alpharag
Artcare ™
 Scavengel ™ cloth
 Activated charcoal
cloth
 Corrosion Intercept ™
films and bags (plastic
impregnated with
finely divided copper)

47. Protective Housing Materials
Activated charcoal and
Zeolite-containing
potassium permanganate
alkaline rag board
sheets

48. Protective Housing Materials
 Capacity to counteract
pollutants not easily
determined
 Shelf life not easily
determined
 More expensive than
traditional housing
materials

49. END