Hello Jim,
I’ve been following the window light blocking conversation with interest. The prospect of spending money and time for highly specialized fabrics or felts, for a highly specialized purpose, which may or may not be a future necessity, just doesn’t feel affordable or practical to me. In comparison, I believe my simple, flexible, and inexpensive alternative approach has much to offer.
I’ve been stocking up on large Polar Fleece blankets, as a multi- purpose basic material, from my local thrift store, where I can often find a queen or king size for around $10. Two or three folded layers will block out any light as necessary. The fabric can also be used for clothing, for insulation, for padding, and for so much more. I prefer to think in terms of basic “building block” materials that can serve many functions, and this is one good example.
Keep up the great work! – J.S.
JWR Replies: Regardless of your solution, be sure to check your completed handiwork from outside your house on a dark night, first with your naked eye, and then with a starlight scope. Any small remaining light leaks (typically seen around the edges) can be remedied with black gaffer’s tape.