From: G6JPG@255soft.uk   
      
   On Tue, 16 Feb 2021 at 23:03:39, Ian Goddard    
   wrote (my responses usually follow points raised):   
   >On 16/02/2021 18:04, J. P. Gilliver (John) wrote:   
   >> they mostly _are_ in pencil (which makes it amazing they've survived   
   >>as  well as they have).   
   >   
   >Pencil, being graphite, is stable.  So is Indian ink.  Bleu-black ink,   
   >however, fades to brown.  The bencil stood a better chance of surviving   
   >then ink.   
   >   
   >Ian   
      
   It is, however, more susceptible to rubbing, as it doesn't really "soak   
   in", or if it does, to a much lesser extent.   
      
   So depends how much the books were accessed. Probably several times near   
   generation (to do what the census was for!), then not for a century or   
   so. Then I don't know, until microfilming - probably hardly at all after   
   that.   
   --   
   J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf   
      
   Anything you add for security will slow the computer but it shouldn't be   
   significant or prolonged.  Security software is to protect the computer, not   
   the primary use of the computer.   
   - VanguardLH in alt.windows7.general, 2018-1-28   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)