I had a great Study Session on Indigos at the AQSG meeting in Bloomington on Friday. We did discuss how to tell a resist from a discharge indigo from the top of the quilt. Kay Triplet, one of the class members, had some very good thoughts...a resist may show a little leaking of color into the design if the edge of the resist print is not as thick as the center portion. The discharge print may show the opposite--a little leaking of discharge (slightly lighter color) outward from the edge of the design--as the discharge paste may 'leak' beyond the edges of the design.
The other hot topic in the Indigo session was how to tell early from late Indigo prints. Sue Reich had a wonderful pieced quilt c. 1837 which was assorted indigos. Generally I think of early Indigo patterns as being larger and fancier than those seen after the Economic Depression of 1893 when so many mills went out of business, used cheaper greige goods and went to smaller simpler designs.
Sue's quilt confirmed my theory. Many of the Indigo printed patterns were large and complex although there were several patterns that were tight and neat--i.e. small rings. I did get some time after the Session to really look at the quilt and the Indigos ( Thank you Sue!) and I also noticed that some of the larger designs were on more coarsely woven grounds.
So some possible clues to early (before the last decade of the 19th century) Indigo prints are resist printing ( discharge is after 1813..in England), coarsely woven grounds and large complex patterns.
One of the excellent papers presented was "Prussian Blue: Its Development as a Colorant and Use in Textiles" by Anita Loscalzo. I have several sample books with wonderful Prussian Blue examples.
I am working on my daughter's computer today--no scanner and no samples books. The next post will be from home and filled with visuals!