-------- Original Message -------- Subject: RE: invisible stamps Date: Thu, 5 Sep 2013 07:37:24 +0000 From: Brendan Whyte <[log in to unmask]> To: mapsL <[log in to unmask]> Regarding embossing stamps The Parliamentary Library of Australia (now the National Library of Australia) used to use these. The stamp featured two concentric ovals, with our name written in between. We are finding now (50-100 years on) that on some maps, this had acted over time like a hole punch, and we have a number of maps with oval holes... Stamper beware! Dr Brendan Whyte Assistant Curator of Maps National Library of Australia