I had to take a reference picture of this card for another project today.
When I looked closely at the picture in i-photo I realised I had no idea what Nainsook meant, easy to jump to a conclusion because I know what bias binding is but in The Oxford Dictionary I found this:-
noun:-
a fine, soft cotton fabric, originally from South Asia, often found with a woven stripe.
Origin:
late 18th century: from Hindi nainsukh, from nain 'eye + sukh 'pleasure'
and with an online search I came across this Etsy posting, showing the pictures below, for an 'Antique White Nainsook & Lace Apron'. And it's only $15.00
If a translation of Nainsook is 'Pleasant on the eye' it's a fair description, I reckon.