Deterioration of a Mirror's Silvering - Revision history

Rickerjones at 14:46, 12 June 2010

2010-06-12T14:46:04Z

← Older revision		Revision as of 14:46, 12 June 2010
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	<references />		<references />

	[[Category:Artifacts]]		[[Category:Artifacts\|Mirror]]

Moleski at 23:43, 1 May 2010

2010-05-01T23:43:36Z

← Older revision		Revision as of 23:43, 1 May 2010
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	== References ==		== References ==
	<references />		<references />

			[[Category:Artifacts]]

Moleski: /* The artifacts in question */

2010-05-01T23:42:13Z

The artifacts in question

← Older revision		Revision as of 23:42, 1 May 2010
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	== The artifacts in question ==		== The artifacts in question ==
	[[File:8 S 18.jpg\|thumb\|left\|2-6-S-18]]		[[File:8 S 18.jpg\|thumb\|left\|2-6-S-18]]
	[[File:Compact-mirror.png\|thumb\|2-8-S-1]]		[[File:Compact-mirror.png\|thumb\|2-8-S-1 and 2-6-S-18]]
	In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>		In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>

Moleski: /* The artifacts in question */

2010-05-01T23:41:47Z

The artifacts in question

← Older revision		Revision as of 23:41, 1 May 2010
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	== The artifacts in question ==		== The artifacts in question ==
	[[File:8 S 18.jpg\|thumb\|left]]		[[File:8 S 18.jpg\|thumb\|left\|2-6-S-18]]
	[[File:Compact-mirror.png\|thumb]]		[[File:Compact-mirror.png\|thumb\|2-8-S-1]]
	In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>		In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>

Moleski at 23:40, 1 May 2010

2010-05-01T23:40:53Z

← Older revision		Revision as of 23:40, 1 May 2010
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	== The artifacts in question ==		== The artifacts in question ==
	[[File:8 S 18.jpg\|thumb]]		[[File:8 S 18.jpg\|thumb\|left]]
	[[File:Compact-mirror.png\|thumb]]		[[File:Compact-mirror.png\|thumb]]
	In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>		In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>

Moleski: /* The artifacts in question */

2010-05-01T23:39:25Z

The artifacts in question

← Older revision		Revision as of 23:39, 1 May 2010
Line 9:		Line 9:
	== The artifacts in question ==		== The artifacts in question ==
	[[File:8 S 18.jpg\|thumb]]		[[File:8 S 18.jpg\|thumb]]
			[[File:Compact-mirror.png\|thumb]]
	In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>		In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>

Moleski: /* The artifacts in question */

2010-05-01T23:29:46Z

The artifacts in question

← Older revision		Revision as of 23:29, 1 May 2010
Line 8:		Line 8:

	== The artifacts in question ==		== The artifacts in question ==
			[[File:8 S 18.jpg\|thumb]]
	In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>		In [[TIGHAR\|TIGHAR’s]] [[Niku IIII\|2001 mapping and test excavation work]] at the [[Seven Site]], we found the artifact we labeled [[2-6-S-18]] -- a small, thin shard of flat glass with a beveled edge. In [[Niku V\|2007]], several meters away, we found artifact [[2-8-S-1]], another such shard that turned out to fit the first, indicating that the original piece had been a rectangle, about 6.5 x 7.5 cm. in size (and about 2 mm. thick). We immediately suspected that we were looking at the remains of the mirror from a woman’s compact, and in 2009 [[Karen Hoy]] found an antique compact on eBay with a mirror that precisely matched artifacts [[2-6-S-18]]/[[2-8-S-1]] in all dimensions.<ref>I am grateful to Karen Hoy for reminding me of the relevant catalogue numbers and supplying the dimensions of the artifacts.</ref>

Moleski: /* Truck mirror outdoors */

2010-05-01T23:13:50Z

Truck mirror outdoors

← Older revision		Revision as of 23:13, 1 May 2010
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	== Truck mirror outdoors ==		== Truck mirror outdoors ==

	I began with a rectangular mirror that had spent several years on the visor of my pickup truck. Prying it out of its casing, I found that the silvering was sandwiched between the glass and a rather rubbery backing. On June 1st, 2008, I exposed the mirror to the elements by placing it, back (coated)side up, in a gravel filled pond in my backyard in Silver Spring, Maryland. This pond houses the outlet for a pump, which I occasionally turn on to send a small stream of water cascading down to a larger, lower, wetter pond with a resident fish population. Thus the mirror was exposed to sunlight, rain, occasional water baths, microbial action and birds. My backyard lacks crabs, and does not get as hot or bright as the Seven Site, but it was the best surrogate for Nikumaroro I could find.		I began with a rectangular mirror that had spent several years on the visor of my pickup truck. Prying it out of its casing, I found that the silvering was sandwiched between the glass and a rather rubbery backing. On June 1st, 2008, I exposed the mirror to the elements by placing it, back (coated) side up, in a gravel filled pond in my backyard in Silver Spring, Maryland. This pond houses the outlet for a pump, which I occasionally turn on to send a small stream of water cascading down to a larger, lower, wetter pond with a resident fish population. Thus the mirror was exposed to sunlight, rain, occasional water baths, microbial action and birds. My backyard lacks crabs, and does not get as hot or bright as the Seven Site, but it was the best surrogate for Nikumaroro I could find.

	{\| border="1" cellpadding="5" cellspacing="0" style="margin: 1em auto 1em auto"		{\| border="1" cellpadding="5" cellspacing="0" style="margin: 1em auto 1em auto"
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	\|}		\|}

	I made it a practice to turn the mirror over at the beginning of each month, so both sides would get equal exposure to both sunlight/air and the “ground” surface.		I made it a practice to turn the mirror over at the beginning of each month, so both sides would get equal exposure to both sunlight/air and the “ground” surface.

	== Moving indoors ==		== Moving indoors ==

Moleski at 23:05, 1 May 2010

2010-05-01T23:05:42Z

← Older revision		Revision as of 23:05, 1 May 2010
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	Thus it appears that a mirror, exposed to conditions roughly similar to those at the Seven Site, loses its backing, and its sandwiched silvering, in about two years. Even if conditions in my Maryland backyard and home office are not perfectly analogous to those at the Seven Site, there seems no reason to think that a mirror’s backing and silvering would survive seventy years in the latter venue. It is possible, of course, that the mercury used as silvering in pre-1940 mirrors was more stable than the aluminum used in modern mirrors, but I see no reason to assume this, and in any event have no pre-1940 mirrors with which to experiment. I anticipate continuing the experiment until both mirrors lose their silvering entirely, but have prepared this preliminary report in case I fail to survive the upcoming Niku VI expedition (One can’t be too careful).		Thus it appears that a mirror, exposed to conditions roughly similar to those at the Seven Site, loses its backing, and its sandwiched silvering, in about two years. Even if conditions in my Maryland backyard and home office are not perfectly analogous to those at the Seven Site, there seems no reason to think that a mirror’s backing and silvering would survive seventy years in the latter venue. It is possible, of course, that the mercury used as silvering in pre-1940 mirrors was more stable than the aluminum used in modern mirrors, but I see no reason to assume this, and in any event have no pre-1940 mirrors with which to experiment. I anticipate continuing the experiment until both mirrors lose their silvering entirely, but have prepared this preliminary report in case I fail to survive the upcoming Niku VI expedition (One can’t be too careful).

	~~Fig~~. 4A: Truck ~~Mirror Fig. 4B: Estee Lauder~~ Mirror as of 5/1/10 as of 5/1/10		{\| border="1" cellpadding="5" cellspacing="0" style="margin: 1em auto 1em auto"
			\| [[File:Mirror-experiment-06.gif]]
			\|'''Figure 4A''': Truck Mirror as of 5/1/10
			\|}

			{\| border="1" cellpadding="5" cellspacing="0" style="margin: 1em auto 1em auto"
			\| [[File:Mirror-experiment-07.gif]]
			\|'''Figure 4B: Estee Lauder Mirror as of 5/1/10
			\|}


	== References ==		== References ==
	<references />		<references />

Moleski: /* Two mirrors, indoors */

2010-05-01T23:01:26Z

Two mirrors, indoors

← Older revision		Revision as of 23:01, 1 May 2010
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	{\| border="1" cellpadding="5" cellspacing="0" style="margin: 1em auto 1em auto"		{\| border="1" cellpadding="5" cellspacing="0" style="margin: 1em auto 1em auto"
	\| [[File:Mirror-experiment-04.gif]]		\| [[File:Mirror-experiment-05.gif]]
	\|'''Figure 3''': Truck mirror As of 5/1/09		\|'''Figure 3''': Truck mirror as of 5/1/09
	\|}		\|}

			== Changing the surface analog ==

	During the summer of 2009, one year into the experiment with the truck mirror and six months into it with the Estee Lauder, it occurred to me that the sand/borax mixture used during the winter was probably a more accurate analog with Nikumaroro conditions than the gravel used during the summer, but that the outdoor exposure to the elements was reasonably analogous to Nikumaroro conditions. Accordingly I elected to combine the two variables, creating a bed of sand (about 90%) and borax (about 10%), with some gravel to mimic the Seven Site’s rubbly environment, in an outdoor birdbath. Placing both mirrors there, I then carried on as usual. I noted little change in either mirror over the next several months. On October 1st, 2009, I returned both mirrors to their winter quarters under my desk. By December 2009, the back of the truck mirror seemed to be thinning, and the several clear areas with neither silvering nor backing were getting larger. The silvering continued to show signs of dissipating, leaving the gray backing showing through the glass. The Estee Lauder mirror showed a pattern of pinholes and patches of vanished silvering, mostly concentrated in the oval pattern formed by the adhesive on the back of the backing. By February 2010 this pattern was quite marked, and pinholes were common all over the Estee Lauder mirror.		During the summer of 2009, one year into the experiment with the truck mirror and six months into it with the Estee Lauder, it occurred to me that the sand/borax mixture used during the winter was probably a more accurate analog with Nikumaroro conditions than the gravel used during the summer, but that the outdoor exposure to the elements was reasonably analogous to Nikumaroro conditions. Accordingly I elected to combine the two variables, creating a bed of sand (about 90%) and borax (about 10%), with some gravel to mimic the Seven Site’s rubbly environment, in an outdoor birdbath. Placing both mirrors there, I then carried on as usual. I noted little change in either mirror over the next several months. On October 1st, 2009, I returned both mirrors to their winter quarters under my desk. By December 2009, the back of the truck mirror seemed to be thinning, and the several clear areas with neither silvering nor backing were getting larger. The silvering continued to show signs of dissipating, leaving the gray backing showing through the glass. The Estee Lauder mirror showed a pattern of pinholes and patches of vanished silvering, mostly concentrated in the oval pattern formed by the adhesive on the back of the backing. By February 2010 this pattern was quite marked, and pinholes were common all over the Estee Lauder mirror.