Re: Palladium on vellum
Hi Loris "Vegetable (paper) parchment is made by passing a waterleaf made of pulp fibers into sulfuric acid. The sulfuric acid hydrolysises and solubilises the main natural organic polymer present in the pulp wood fibers, the cellulose. The paper web is then washed and neutralized in water, which stops the hydrolysis of the cellulose and makes a kind of cellulose coating onto the waterleaf. The final paper is dried. This coating is a natural cement, non porous that gives to the vegetable parchment paper its grease resistance which is the main feature of this paper along with its semi-translucancy. Other processes can be used to obtain grease resistant paper, such as by highly beating the fibers giving an even more translucent paper with the same grease resistance. Silicone and other coatings may be applied to parchment. One can obtain grease resistance by waxing the paper or by using fluorine based chemicals. When a silicone coating treatment is applied to the surface of the paper, this produces a cross-linked material with high density, stability and heat resistance and low surface tension which imparts good anti-stick or release properties. Chromium salts can also be used to impart moderate anti-stick properties." (from http://wapedia.mobi/en/Parchment?t=6.) I have read somewhere else that the sulphuric acid process process actually involves passing the paper through several acid baths, each weaker than the one before it, then an alkali bath to neutralise the acid. After that the paper is washed and put through heated rollers. It all sounds rather industrial. Don Sweet ----- Original Message ----- From: "Loris Medici" <mail@loris.medici.name> To: <alt-photo-process-l@usask.ca> Sent: Monday, May 25, 2009 8:50 AM Subject: Re: Palladium on vellum > Very interesting Marek, congrats & thanks for sharing. I prefer the gold > one -> suits the subject matter better IMHO. I also want to try that! > That's if I manage to find such a transparent paper which is able to take > wet processing (+ is chemically compatible with iron processes). > > I may try to process Masa paper (which is easier to work with than your > vellum I presume) in sulfuric acid to make it more transparent -> if I'm > not mistaking that's how they produce translucent / semi-transparent > paper. Anyone with details about this? > > Regards, > Loris. > > > 24 Mayıs 2009, Pazar, 11:25 pm tarihinde, Marek Matusz yazmış: > > > > > > All, > > > > > > > > Finally after being inspired by Dan Burkholher's show I gothered all the > > supplies and made my first palladium/platinum prints on vellum with silver > > and gold leaf. This is one of my favorite prints that I printed many times > > in gum, so I include two versions of gum prints. The vellum that I am > > using now is very translucent, but it crinckles and creases so easlily. I > > am learning how to deal with it. It did not really like being ironed while > > wet. You can see creases that are a result of that. On the other hand I am > > enjoying the wrinkles and hande-made feeling of the prints. > > > > My scanner broke down so these are photographs of the prints taken outside > > with the sun positioned to acccent the vellum surface. > > > > Marek > > > > http://picasaweb.google.com/marekmatusz1/PalladiumOnVellumSilverAndGoldLeaf# > > > > > > > > You have to copy and paste the link into your browser > > > > > > > > _________________________________________________________________ > > Insert movie times and more without leaving Hotmail®. > > http://windowslive.com/Tutorial/Hotmail/QuickAdd?ocid=TXT_TAGLM_WL_HM_Tutorial_QuickAdd1_052009 > > > >
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