The legislation you refer to was enacted by Parliament to protect the British silk and woolen industries from the highly popular India cotton trade goods flooding the market. The Act (United Kingdom, Statutes of the Realm Act 1774, 14 Geo. III, cap. 72) was in effect 1774-1811 and decreed that any foreign Cotton was taxed if it was brought into England except for that cotton cloth woven (and often printed) specifically for export to the colonies. These cotton cloths had to be marked with three blue threads in both selvedges, thus indicating the date and place of origin (i.e England, 1774-1811) with the destination of the American colonies.  The import tax would be refunded when it was shown, by the blue lines,  that the raw cotton had been exported. These blue lines are often found in copperplate-printed textiles, with selvedge-to-selvedge widths typically ranging between 24"-30" (62 cm- 75 cm). The date boundaries can sometimes can be narrowed further by the image printed on
  the t
extile (political themes especially).

Please note that the law required THREE blue threads were to be woven in COTTON cloth only. It did not apply to woolen cloth.
Two blue threads woven into woolen cloth (and approx 12"-13" wide, selvedge to selvedge) is often found in 18th c. needlework, however, this detail is not an indicator of date or place of manufacture. It is just another example of shared use of materials between England and America.

Acts of Parliament can be searched at http://portcullis.parliamjent.uk (House of Lords Records Office)
as well as
http://bopcris.ac.uk ( the British Official Publications Collaborative Reader Information Service's web site to search and browse information from British Official Publications 1688-1995.)

hope this helps.

Virginia


--
Virginia J. Whelan
Textile Conservator
Filaments Conservation Studio
740 Hazelhurst Avenue
Merion Station, Pennsylvania 19066
610-664-0927

 -------------- Original message ----------------------
From: "Sandra L. Troon" <[log in to unmask]>
> Joan,
> I do not have a reference for this, but I remember that years ago while
> doing grad research I learned that the two blue threads/stripes woven
> into the selvedges of wool fabrics was required in England during a
> particular era. It was a trade regulation/requirement. I can't remember
> now whether it was specifically for export regulations or just to
> identify the fabric as English manufactured. I know that I often see this
> sort of selvedge in the wool fabric used for samplers in the 1800's and
> everytime I do I wish I had kept better track of that bit of history.  If
> this is the sort of information you are looking for I will try to find
> the referrence in my now very old notes.
>
> Sandy Troon
> Oregon Textile Workshop
>