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iztok @izo 23. Mar 2011, 18:12

tole mi najde pod prvi link, mogoče pride prav:

LIGHT

There are three types of light: ultraviolet (UV) light, infrared radiation and visible light. All three
types are harmful to artifacts and the damage caused by all light is cumulative and irreversible.
In fact, displaying an object under ideal museum lighting conditions for just a few weeks could
have the same effects as exposing it to bright sunlight for a day or two.

Exposure to light in all forms causes a chemical reaction to happen within the molecular level of
an artifact. Light exposure can cause textiles to weaken and fade, dyes and paints to darken or
change color, and paper to become weak, bleached, yellowed or darkened. The best preservation
practice would be to house all artifacts in complete darkness. Although the exhibition needs of
museums will not allow for that, you can take several steps to reduce the harmful effects of light.

Because UV light is the most harmful type of light, make every effort to exclude or filter UV
sources. The most common sources of UV are natural daylight and fluorescent lamps, but
tungsten-halogen lamps and high density discharge (HID) lamps also give off significant levels
of UV radiation. Sources of natural light should be eliminated from all museum exhibit and
storage areas when possible, or filtered when elimination is not possible. Cover windows with
shades, drapes or blinds. Film products and Plexiglas-type sheeting are other UV filtering
options.

Many small museums are lit by fluorescent lights. Museums can reduce the amount of UV
exposure from these lights by installing UV filters on the bulbs. Filters come in the form of hard
plastic tubes or soft plastic sleeves, either of which can be wrapped around the light bulb. Prices
of the UV filters start at around $50 per dozen and can be purchased from a specialty lighting
store or from an archival supply catalog. Filters generally block up to 98 percent of all UV light,
but they lose their efficiency over time and should be replaced approximately every 8–10 years.

While incandescent lights do not give off UV, they can emit a significant amount of heat.
Therefore, incandescent lights should not be placed inside or near exhibit cases. Use the lowest
wattage possible and make sure areas surrounding the incandescent bulbs are well ventilated.

Even visible light can damage the museum’s collections. The museum can reduce the harmful
effects of visible light by simply turning off the lights as much as possible. Lights in the exhibit
area should be turned on only when visitors are on tour or when staff is working on the exhibits.
Keep the storage area completely dark except for when staff is retrieving or working with an
artifact. Ideally, each exhibit area and the storage area should have its own light switch so that
light can be turned on only in the area where needed.

The following chart provides the recommended light levels for artifacts on exhibit. When

Artifact Preservation - 3

exhibiting mixed collections, choose the recommended light level for the most sensitive artifacts
on display. Light levels can be measured with light meters (lux and UV), which can be purchased
from archival supply catalogs.

Visible light
Sensitive collections
Maximum:
Including textiles, watercolors, 50 lux (5 footcandles)
photographs and other papers

Less sensitive collections
Including oil paintings, wood
and leather

Least sensitive collections
Including most metal,
ceramics, stones and glass

Maximum:
150 lux (15 footcandles)

Maximum:
300 lux (30 footcandles)

Ultraviolet (UV) light
Ideal:
0 - 10 microwatts per lumen
Maximum:
75 microwatts per lumen
Ideal:
0 - 10 microwatts per lumen
Maximum:
75 microwatts per lumen
Ideal:
0 - 10 microwatts per lumen
Maximum:
75 microwatts per lumen

Another way to reduce the harmful effects of light on museum objects is to rotate the artifacts
on display. Return sensitive objects to storage after three months; less sensitive artifacts can be
displayed longer, but periodically return them to storage for “rest.”


www.thc.state.tx.us/museums/.../BasicGuideforPreservHistArtifacts.doc
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Janez Pelko @Wartburg 24. Mar 2011, 10:58

George je napisal/a:
Wartburg je napisal/a:
Moje mnenje je, da ni le UV svetloba kriva za degradacijo materialov, verjetno ima vpliv ves vidni spekter.
O tistih 'UV' steklih na gradovih: kolikor je meni znano, so vse navadne šipe že UV filtri. Nekako si ne predstavljam, da bi se lahko sončil za stekli, kja šele, da bi dobil opekline.


Morda bi raje brskal po internetu in ne spominu...

http://www.sunprotection.net/filmprotection.html

http://iopscience.iop.org/0031-9155/44/4/008;jsessionid=B4CA7E8403576C4C9B16F16DD4F8FBDC.c3


http://www.newton.dep.anl.gov/askasci/gen06/gen06495.htm


In zakaj bi brskal po internetu, če mi spomin (in zdrava pamet) še služi?
Sem mar kako nebulozo ustrelil?
Naj citiram zadnji link: Standard glass will block 95% of UV radiation that causes
tanning (activation of melanocytes)
Sicer pa, kje pa piše, da je vse, kar je na internetu, čista resnica?

O tem, da je pa ves spekter škodljiv za barve in materiale, se je pa tu tudi že pisalo nedolgo nazaj.
 1   

Uroš Miklavčič @Ulrich 1. Jun 2011, 19:53

Verjetno ste že opazili, da sem s svojim delom na tem področju zaenkrat prišel do konca. V kolikor vas zanimajo izsledki si preberite članek na https://www.slo-foto.net/novice/2011/06/01/ali-bliskavice-povzrocajo-skodo-v-pigmentih-zaradi-uv-sevanja
Zahvala: cedo
blog: [url=http://blog.miklavcic.si]blog.miklavcic.si[/url] | twitter: [url=http://twitter.com/uros_m]@uros_m[/url] | galerija: [url=https://www.slo-foto.net/portfolio/Ulrich]SloFoto[/url] | podjetje:[url=http://miklavcic.si] miklavcic.si[/url]
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NikonGeek @NikonGeek 5. Jul 2011, 21:16

Varnostniki ne jebejo ker so zabiti kar se tega tiče. Nobenmu ne moreš dopovedat da maš UV filter...
 0   

PrimozS @PrimozS 6. Jul 2011, 20:06

NikonGeek je napisal/a:
Varnostniki ne jebejo ker so zabiti kar se tega tiče. Nobenmu ne moreš dopovedat da maš UV filter...


So what's your point?


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