Helen Frankenthaler (1928-2011) is considered to be one of the great American artists of the twentieth century.
[she] ‘…is widely credited for playing a pivotal role in the transition from Abstract Expressionism to Color Field painting. Through her invention of the soak-stain technique, she expanded the possibilities of abstract painting…’ —Frankenthaler Foundation (link below)
This video is a bit wordy at 5 minutes, but even viewed in silence, it provides a nice visual overview of her – pioneering – work during this period.
If you wish to learn more: