Focus
Another example of the Vermeer's supreme control of the medium that might easily escape attention can be found in a stamp-sized detail that represents two taut threads at the center of The Lacemaker.
Other than possessing a steady hand and perfect vision, to render this passage the painter must have determined the appropriate viscosity of his paint in order to obtain a constant, yet controlled flow from the nearly invisible point of his fine-tipped brush. Moreover, careful inspection reveals that the tone of the right-hand thread is slightly lighter than that of the left-hand thread, which, instead, is slightly blurred as well. The subtle differentiation in focus and tone makes the right-hand thread appear softly illuminated while the left-hand thread appears to be set slightly deeper in space than its counterpart, encompassed in an envelope of luminous penumbra cast by the lacemaker's hand.
To achieve the precision observed in the two threads, Vermeer most likely employed a so-called rigger's brush. The term "rigger's brush" refers to a type of long, thin brush traditionally used in detailed painting work, most notably for painting the rigging in pictures of ships, which is how the brush got its name. The long bristles are excellent for producing long, continuous lines, making them ideal for painting ropes and lines in marine paintings, as well as fine details in other types of painting. The lengthy hairs of the rigger brush permit it to hold a sizable amount of paint which slowly flows as the painter drags the very tip of the brush over the surface of the canvas. This is to ensure the maximum effect of creating a long, smooth line. However, the use of the rigger's brush can be tricky. In order to achieve the perfect line, the brush must be loaded with the right amount and consistency of paint. Too much paint and the line may be thicker than intended and reveal any movement in the hand. With too little paint, the line may stop before you need it to. Trying to then match up a new section of line will be tricky and will end up looking clumsy.