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Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
In a very old book there was a suggestion for making a black coating: Dissolve lampblack in gasoline and paint the wood.
Any ideas on how such a black painted surface made this way could be identified as having been made this way? Assume 80 years have passed.
Apart from scraping the chimneys of kerosene lamps, where does lampblack come from these days? Does old lamplack have a way of being dated as made pre- A bomb era?
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
Something very like lampblack is still made under the name carbon black (original name award there) Since most of it is, and always was made from petroleum, you couldn't radiocarbon date it. It would be difficult to tell how old it was. It would probably be easier to date the wood.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
radiotech wrote ...
In a very old book there was a suggestion for making a black coating: Dissolve lampblack in gasoline and paint the wood.
Any ideas on how such a black painted surface made this way could be identified as having been made this way? Assume 80 years have passed.
Apart from scraping the chimneys of kerosene lamps, where does lampblack come from these days? Does old lamplack have a way of being dated as made pre- A bomb era?
The main industrial use of carbon black nowadays is as a rubber additive in motor car tyres. It is considered to be a carcinogen.
Surface coatings of any sort do not lend themselves well to radiometric dating, because of surface purity and contamination issues. Useful samples likely to yield reasonably accurate dates must be taken from from freshly exposed material completely free of cracks, fissures, and porosities that could have admitted contamination from the outside.
There are several means by which wood can be dated, including tree ring dating which can be accurate to a single year for certain woods in certain periods and geographical locations. Obviously, if you have a date for the wood, that is the earliest date at which any surface coating could have been applied.
Lampblack harvested from paraffin lamp chimneys would consist of porous carbon microparticles suspended in heavy hydrocarbon tars. The latter would be soluble in petrol, but the carbon particulates would not, so you might possibly be able to identify them with a microscope if you were sufficiently painstaking and knew what you were doing.
Registered Member #2261
Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581
I worked in the labs of a company that made inks with carbon black once. I was told the carbon black they used was made by burning natural gas with a restricted air supply. I think they were very fussy about the grade of carbon black used as the game was all about keeping the properties of the ink constant, year after year. I think there are many grades of carbon black and it's possible a manufacturer could identify your grade in their labs, which might help tie down the age.
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Lampblack paint
