[alt-photo] Re: Trying to understand how ferric chloride reacts with gum arabic

[Kees Brandenburg]

On 8 dec 2010, at 15:55, Mike and Jan Andrews wrote:

> You say that you tried adding ferric chloride to the ferric ammonium citrate in Halvor's Chiba system, and it didn't work well.  I'm not sure why it would work.  Certainly adding citrates tends to prevent ferric salts hardening gum or gelatine (oxalates and tartarates do so less).  But it's not obvious to me how the ferric chloride would help in this case.


The reason for trying the mix I found in this patent: 
http://www.google.nl/patents?id=ii4CAAAAEBAJ&zoom=4&dq=RELIEF%20%20IMAGE%20PROCESS%20UTILIZING%20A%20SIMPLE&pg=PA74#v=onepage&q&f=false

-k