RE: pt/pd mounting

[EJN Photo <ejnphoto@sbcglobal.net>]

I doubt he'll mind. I think we would agree that a pH where paper is happy is
neutral and above? Then Camden's question regarding what to mount it on
would be best answered," what ever is best for that paper and if possible
something to block the interaction of SO2 with the PT."

Eric  

Eric Neilsen Photography
4101 Commerce Street, Suite 9
Dallas, TX 75226
214-827-8301
http://ericneilsenphotography.com
 
Skype : ejprinter> -----Original Message-----
> From: Liam Lawless [mailto:lawless@bulldoghome.com]
> Sent: Monday, September 11, 2006 3:17 PM
> To: alt-photo-process-l@usask.ca
> Subject: RE: pt/pd mounting
> 
> The following is copied from Mike Ware's page at
> http://www.mikeware.co.uk/mikeware/Eighth_Metal.html.  Hope he
> won't mind if
> he finds out...
> 
> 
> Liam
> 
> The third attribute -of permanence- had been a longstanding
> issue ever since
> the Fading Committee of the Photographic Society reported in
> 1855, and the
> Duc de Luynes' prize for a permanent process was won by
> Poitevin (for Carbon
> printing) in 1859. Willis's platinum research was also
> stimulated by the
> quest for permanence, but even after he had finalised his
> procedures, we
> find many articles in the photographic literature complaining
> of incomplete
> clearing, and offering suggestions for curing yellowed
> highlights in
> Platinotypes. A modern investigation of this problem, and the
> extent to
> which it can be attributed to residual iron, has recently been
> carried out
> by Rees and Gent at the Victoria & Albert Museum (48). Although
> the metal
> constituting a Platinotype image is invulnerable, its paper
> substrate is
> certainly not. Acid embrittlement of the cellulose is the other
> besetting
> problem that Platinotypes present to the conservator. The
> build-up of acid
> is exacerbated by the catalytic action of the platinum black
> itself, which
> assists the conversion of sulphur dioxide to sulphur trioxide
> and hence to
> sulphuric acid (49).