To avoid repeated typing of the same document, an easy-to-use copier was used in the 1950s to print worksheets and classroom materials. Government agencies and companies also often used spirit duplicators. Two sheets of paper were put into a typewriter: A top sheet was stiff and smooth (stencil), the second sheet (transfer sheet) was coated with coal and wax and faced the back side of the stencil. The pressure of writing or typing transferred the text to the stencil as a mirror image. The stencil was then put onto the drum of the duplicator. When turned, alcohol was spread across the stencil, thereby gradually stripping the colored layer from the stencil, and transferring it to paper. As the crank turned, paper was moved from the stack, had color transferred to the surface, and was then restacked. The finished sheets continued to smell of alcohol for quite some time.