Shielding Textiles
At a few microns of silver the coating is a fraction of one skin depth. Nearly all the shielding is reflection, and making it thicker buys almost nothing.
— dB
Total attenuation of the incident field
This is the plane-wave far-field result for a continuous conductive sheet, and a fabric is not continuous — apertures at the weave, seams, closures and cable entries govern real enclosures and routinely cost tens of decibels the material itself would have delivered. Near-field magnetic shielding at low frequency follows entirely different rules and this will overstate it badly. Multiple-reflection correction is omitted, which is conservative for thick shields and optimistic where thickness is well under a skin depth. Verify by measurement to ASTM D4935 or a full enclosure test.
EMI Shielding Effectiveness of Metal-Coated Fabric — free, with the formula and a worked example, at Textile School.