In the age of computer-aided design and easy printing, traditional blueprint copies are gradually losing their popularity. However, there are still industries and professions that rely heavily on physical blueprint copies, and for them, finding the right paper is crucial. Blueprint diazo paper is designed to meet the specific requirements of handling large drawing copies and the subsequent coating and development of the image.

One of the primary considerations when choosing blueprint diazo paper is its strength. Large drawing copies often need to be handled in difficult environments, and therefore require a paper that can withstand the rigors of transportation and use. The paper’s strength ensures that it won’t tear or become damaged during the handling process.

In addition to strength, blueprint diazo paper must also have a well-sized and chemically neutral, uniform surface. This is important for the coating and development of the image. The sizing of the paper allows for the even distribution and absorption of the chemicals used in the blueprinting process. A chemically neutral surface ensures that the image development is not affected by any unwanted reactions or discoloration.

Opacity and brightness are also key factors in choosing blueprint diazo paper. Opacity refers to the paper’s ability to prevent the image from showing through the other side, while brightness influences the clarity and readability of the image. High opacity ensures that the blueprint copy can be viewed without any interference from the underlying surface, while brightness enhances the overall legibility of the document.

Typically, blueprint diazo paper is manufactured using bleached kraft, which gives it the desired strength and durability. In the past, bleached sulfite was widely used for this purpose. The paper is rosin sized, meaning it is treated with a substance derived from pine resin, which helps to improve its resistance to water and smudging. In addition to rosin sizing, wet-strength resin is added to enhance the paper’s resistance to tearing when wet. This is particularly important as blueprint copies are often exposed to moisture during the development process.

To further enhance the paper’s properties, it is treated in the size press. This additional treatment helps to ensure that the paper has a uniform surface and optimal absorbency. The size press treatment also aids in improving the paper’s ability to withstand handling and the application of chemicals during the blueprinting process.

While the use of traditional blueprint copies may be declining in some industries, there are still professions that heavily rely on them. For these individuals, finding the right blueprint diazo paper is essential. The paper’s strength, well-sized and chemically neutral surface, opacity, and brightness all contribute to the successful reproduction of large drawings. With the right blueprint diazo paper, professionals can continue to create accurate and durable blueprint copies for years to come.