The factory aperture stays are .007 inch thick copper painted(?) black. They are folded in half and pressed onto the edge of the aperture opening. The stay is wider at one end and the end goes through a slit in the edge of the curtain and folds over.
I use a 1 inch wood chisel and gently pry the stay open 20° or so turn the end piece up 90° and remove the stay from the curtain. Once separated I scrape the inside clean.
I position the stay onto the curtain with a thin strip of contact cement on one side of the V opening then crimp closed with the flat section of needle nose pliers. I glue the edge piece to the curtain and occasionally the 90° breaks off but the stay and curtain work fine without it.
Replace a curtain only if the backing material has dry rotted and tears easily. Recoat the curtain with Golden Heavy Body Acrylic Artist Paint #1040 Carbon Black. This paint dries flexible, can be diluted and applied in thin coats with a fine bristle artist brush or air brush.
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