Litho vs. Screen Printing: Understanding Sign Manufacturing Techniques
For collectors of vintage advertising signs, appreciating their history and value means understanding how they were made. Two dominant printing techniques reigned supreme for decades: lithography and screen printing. While both resulted in vibrant, eye-catching signs, the methods differ significantly, impacting the sign's appearance, durability, and ultimately, its collectibility. This article delves into the technical distinctions between these processes.
Lithography: The Art of Stone and Oil
Lithography, derived from Greek words meaning "stone writing," was a revolutionary printing process initially developed in the late 18th century. It relies on the principle that oil and water repel each other. A smooth stone surface (originally limestone, later zinc or aluminum) was meticulously prepared. An artist would draw the design onto the stone with a greasy crayon or ink. The stone was then treated with chemicals to fix the image. The oily image accepted ink, while the surrounding areas repelled it.
When printing, the stone was dampened with water, which adhered to the non-image areas. An oily ink was then applied, sticking only to the greasy image. Paper was pressed against the stone, transferring the ink and creating the printed image.
Characteristics of Lithographed Signs:
- Fine Detail: Lithography excels at reproducing intricate details and subtle gradients. You're likely to see sharper lines and a more nuanced image compared to screen-printed signs.
- Smooth Appearance: The image tends to have a smoother, more even finish.
- Generally Thinner: Lithographed signs are often thinner and lighter than their screen-printed counterparts.
- Can Show Signs of Wear: The delicate nature of the lithographic process means these signs can be prone to scratches and loss of gloss.
Screen Printing: A Mesh and Ink Marvel
Screen printing, also known as silk-screening, emerged as a practical alternative to lithography. It involves forcing ink through a mesh stencil supported by a frame. The stencil blocks certain areas of the mesh, allowing ink to pass through only in the desired pattern. Originally, silk was used for the mesh (hence the name), but modern screens are typically made of polyester or metal.
Each color in a screen-printed design requires a separate stencil and printing pass. This makes screen printing somewhat more labor-intensive for multi-color designs.
Characteristics of Screen-Printed Signs:
- Bold Colors: Screen printing often produces vibrant, opaque colors, even on darker backgrounds.
- Thicker Ink Layer: The ink sits on the surface of the sign, creating a noticeable texture.
- Durability: The thicker ink layer often makes screen-printed signs more resistant to scratches and fading.
- Visible Mesh Lines: Depending on the mesh used, very fine lines from the screen may be visible, especially in lighter colors or areas with very fine detail.
Identifying the Method: A Collector’s Guide
Determining which method was used can be tricky, but here are some clues:
- Examine the Ink Layer: Feel the surface. Lithographed signs are generally smooth, while screen-printed signs will have a slightly raised ink layer.
- Look for Mesh Lines: Very fine lines may be visible on screen-printed signs.
- Consider the Detail: Intricate details and fine gradients suggest lithography. Bold colors and a thicker ink layer point to screen printing.
- Material: Early lithographed signs were often on heavier paper stock or cardboard, while screen printing could be found on a wider range of materials, including tin or aluminum.
Conclusion
Understanding the manufacturing processes behind vintage advertising signs enhances the appreciation for these pieces of Americana. Whether it's the delicate artistry of lithography or the bold impact of screen printing, each method contributed to the rich visual landscape of advertising history. Recognizing these differences can also inform your collecting decisions and help you accurately assess the value of your treasured signs.
