![]() ![]() Poor handling: Not washing and drying hands before handling fragile documents or not using gloves when handling materials that could be damaged by contact with oils on the skin (for example: gloves must always be worn when handling metals).Folding materials to fit into a given box or enclosure.Permanent or volatile inks used to label documents (even the back side).Pressure-sensitive (such as "Scotch®" brand) tape to mend tears.Whether intentional or not, this is a risk posed by patrons and staff alike.Įxamples of neglect, mishandling, and mismanagement include: touching photo emulsion with bare hands) or irresponsible operation of access equipment. The unfettered use and handling of materials heightens the general risk of damage-be it through neglectful handling (e.g. One of the easiest areas to implement protections for collections is through careful handling and sensible collections care. This is a risk posed by patrons and staff alike, intentional or not. ![]() Generally, handling and use heightens the risk of damage to your materials, be it through neglectful handling (e.g. Azo dye (also known as the coupler): a colorless chemical that combines with the salt to produce color.Architectural Papers (Diazo) Risks of Handling/Use.diazonium salt: a light sensitive chemical.There are two components in this process: ![]() A blue-line print is not permanent and will fade if exposed to light for weeks or months, but a drawing print that lasts only a few months is sufficient for many purposes. Whiteprinting replaced the blueprint process for reproducing architectural and engineering drawings because the process was simpler and involved fewer toxic chemicals. The light-sensitivity of the chemicals used was known in the 1890s and several related printing processes were patented at that time. It is a contact printing process which accurately reproduces the original in size, but cannot reproduce continuous tones or colors. It is also known as the blue-line process since the result is blue lines on a white background. Whiteprint describes a document reproduction produced by using the diazo chemical process. Introduction of the blueprint process eliminated the expense of photo lithographic reproduction and the need to hand-trace original drawings. Once the drawing is exposed to light the exposed parts of the drawing (the background) became blue, while the drawing lines blocked the coated paper from exposure and remained white. The paper or cloth is pre-coated with a photosensitive chemical mixture of potassium ferricyanide and ferric ammonium citrate. The process starts by taking a drawn image on semi-transparent paper weighed down on top of a sheet of paper or cloth. Herschel had discovered the cyanotype process after a series of experiments. John Herschel, who was a chemist, astronomer, and photographer, developed the process for blueprints in 1842. Blue-printĪ blueprint is a type of paper-based reproduction usually of a technical drawing, documenting architecture or engineering designs. Here we will share some information regarding these two techniques. These processes were discontinued over a period of time because more stable and easier processes were developed later to replace them. This write-up is the summary of our discussion on the topic.īoth these processes ( blue prints and blue lines/white prints) use different light sensitive chemicals for re-producing or copying the original drawings made on translucent paper. Before starting the work, we tried to discuss the material and technique used in making them. These days we are working on a few blue-prints and blue-lines in our lab. ![]()
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