Fumed Silica & Alumina for Platinum/Palladium Printing
July 27, 2012
Bostick and Sullivan started supplying fumed Silica and Alumina last February as an aid to enhancing image quality of alternative printing processes. In respect of platinum/palladium printing it is said to provide better dmax and a deeper matte finish.
Both fumed silica and alumina are extremely fine powdered compounds and can be applied either wet or dry before applying the sensitiser. They are said to be ‘archival’, silica has a neutral ph and tends to give a more warmer tone with slower printing speed whereas alumina is slightly acidic (ph 6.5 to 4.5) giving cooler tones and is generally faster in speed.
Early reports indicate that it does improve dmax on certain papers, although I have yet to see anyone quote actual figures, more side by side comparisons. Coating is critical and needs to be practiced and refined until consistent results are achieved.
We use a number of papers for platinum printing from the thinnest Japanese papers to heavier French watercolour and printing making papers i.e Arches Platine/Cot 320, Fabriano Artistico. The dmax achieved on such papers ranges from excellent to good (1.55 to 1.4 ) Some papers require a pre acid bath to make them suitable for platinum printing which can take the sizing out of papers.
What interests me is that with alumina being slightly acidic it might make previously unusable buffered papers suitable for platinum/palladium printing i.e Rives BFK, a paper used extensively by Irving Penn. I will be testing a range of papers with alumina over the next few weeks and will report back should the findings be positive.