To start a Colonial Knot, hold the thread firmly between your left index finger and thumb and away from the fabric. With the tip of the needle outwardly directed, pass the needle under the thread and then pass the thread over the needle simulating an height. Holding the thread taut with your left hand, turn the needle downward and take it to the back a few threads away. (If you try to use the same hole, the knot is very likely to pull back through and disappear). With the tip of the needle inside the hole, slide the knot down the needle onto the fabric. Slowly push the needle to the back of the fabric while holding the knot in place under your thumb
It is recommended to use perle cotton or any kind of round thread to emphasize the relief of the knot marking a difference with the usual French knot.