Eventually, a patent for an open-mesh, fabric Tea Leaf Holder was filed in 1901 by Roberta Lawson and Mary McLaren of Milwaukee, Wisconsin. Other designs soon followed. During the 1920s, technological advances in the US led to the development of machinery that could make and pack gauze bags. Fabric was then replaced by filter paper strong enough to hold in the tea but light enough to allow the tea color and flavor to seep out into the water. By the 1930s, giant bagging machines on the floors of a dozen American tea packers whirled around the clock, delivering as many as 18,000 assorted teabags each day. Soon the disposable one-cup wonders were found in every American home kitchen, and loose leaf tea began to disappear from store shelves.
The machines that were invented to pack the first patented teabags only allowed the use of small particles of tea. But the industry found that it was not making enough small grades to fill the growing demand for teabags, and so a new manufacturing method was introduced in order to specifically create large quantities of small tea particles for teabags. Thus CTC (cut, tear and curl) manufacture was invented, and the first CTC machines were installed in a number of Assam tea estates in the 1930s. Teas produced by these machines quickly steeped a strong dark liquor, perfect for the addition of milk.