These are always stretched over museum quality mount board before framing to keep them straight and flat. The method of stretching that we used is called lacing.
This is a conservation technique where the needlework is stretched and laced over the museum quality mount board to hold it in place. This is a totally reversible technique as the lace can simply be cut and the needlework can be returned to its original state before framing if this is ever required. We never use such adhesives as tape or glue as these will be harmful to your textile work.
The best way to frame any textile work once it is laced is to overmount as well as frame it. The over mount provides a space between the glass and the stitch work to prevent the delicate stitches from being pushed flat by the glass. For an embroidery this may only require one over mount but with more three dimensional textile work, a double or even a triple mount may be required. With woollen tapestries, the space between the glass and the stitch work is not always necessary as the wool does not flatten down as much as cross stitch. Therefore these can go straight into the frame. However a 'spacer' between the glass and the tapestry may still be needed to frame these properly.
Here we have an example of a framed sampler. The sampler was a wedding present and there was a distinct deadline to have the sampler framed by, the wedding! The sampler was laced over acid free mount board and then a single mount was used to over mount the needlework. To finish off the sampler a simple square oak profile was used. On needleworks (as indeed with most pictures) you do not need to over frame the picture. A simple oak frame with a simple off white mount just complements the subtle tones of the sampler and does not 'drown' the image out.