The major difference between Sardinian Bosa Filet Lace and the Filet Lace that is common in other countries are the motifs and the heavier use of the Linen Stitch (or Cloth Stitch) and the Double Running Stitch used to outline motifs such as flowers, leaves and vines. Together with the Darning Stitch and Dove's Eyes these stitches make far more interesting Filet Lace, both to admire and to make. Bosa is a small town in the north-western part of Sardinia in Italy.
Historically embroidered on both ancient Buratto woven linen or Modano knotted netting, today Sardinian Bosa Filet Lace is done almost exclusively on the Modano knotted netting.
Two variations on the Linen Stitch, the Darning Stitch, the Dove's Eye Stitch, edge finishing and frame mounting instructions can be found here in Italian but the diagrams are clear. How to execute a flower and some rings can be found here: click on the various circles in the photo, this will take you to a close-up photo of that particular stitch and then to the right click on the word: "qui" which is underlined to go to a series of photos of how to execute that particular stitch.
This is a lovely Bosa Filet border from the Italia Invita Forum 2005 book:
At the Sardinian Digital Library you can download a book called Arte Sarda - there are many photos of Bosa Filet Lace starting with Chapter Four on page 246 of the pdf.
Here is a piece from the Poldi Pezzoli Museum in Milan:
At the Online Digital Archive you can download Peasant Art in Italy (text in English) by Charles Holme - the chapter Women's Crafts (page 73 of the pdf) by Elisa Ricci has some exquisite examples of typical Sardinian Filet motifs. (Make sure you download the right file, it's the second listing under Charles Holme!)
The first section in Elisa Ricci's book Old Italian Lace (downloadable from the Online Digital Archive) has many examples of Sardinian Filet Lace. I love these birds:
Visit Tuttoricamo and under the "Techniques" heading you'll find an article called "Filet and Bosa Filet" which has lots of links to pictures. While you're there you can read about ancient Buratto woven linen under the "Materials" heading. Learn about Elisa Ricci in the "Prominent Characters" section.
Thanks to Stefania for the museum photo!