Thank you all for your very helpful comments. They have
been passed on to the person in question. She still hasn't divulged how
she knows fabric is vintage but I hope to find out.
This group is always so willing to share their expertise.
Joan
constance wrote:
Joan -
I would not consider the black light as very useful for dating fabrics.
It is normally the dyes and optical brighteners in the fibers that are
fluorescing. Many natural substances and some natural and synthetic
dyes fluoresce to a certain extent. Synthetic fluorescent dyes were
introduced in the 1870's - though they were not immediately applied to
textiles. Blankophor, an optical brightener, was introduced in l941 in
washing detergents. There are many different types of optical
brighteners used today in the finishing of textile yarns - and
especially in detergents and bleaches. Optical brighteners are dyes
that absorb invisible UV light and radiate it back as blue light. If
historic cellulosic textiles have been washed since the 1940's, they
might fluoresce noticeably under UV light - even if the textiles are
thousands of years old (as I have witnessed). The effect may weaken
over time as some brighteners break down, but products from the last
thirty years can still produce remarkably strong fluorescence. Many
non-Western, village-based cultures do not always use detergents with
optical brighteners. In such cultures, the older ethnographic textiles
do not fluoresce and the new ethnographic textiles do not fluoresce
either.
The primary efficacy of comparing textiles in UV, visible and infrared
light is to help identify variations in color that might point to
restorations - both legitimate and illegitimate. Colors that appear
the same in visible light might be the result of combinations of
different spectral wavelengths, if they are from different dyeings -
thus there would be a divergence of color when the wavelength of the
light source is changed. However, in my experience, such variations
can usually be detected without resorting to this procedure - though
this enhancement is useful when creating photodocumentation.
I hope this helps,
David Walker
office@xxxxxxxxxxxxxxxxxxxxxxx
Walker Textile Conservation, LLC.
369 Montezuma Ave. #592
Santa Fe, NM 87501, USA
ph: 1-505-474-4905
fax: 1-505-473-0257
No virus found in this incoming message.
Checked by AVG - http://www.avg.com
Version: 8.0.138 / Virus Database: 270.5.10/1587 - Release Date: 8/2/2008 5:30 PM
|