Electronic Supplementary Information contains the following files:

ChamberPicture.jpg : Picture of the evaporative chamber used to conduct the experiments. Blue grains in the upper part of the T shape are dried silica gel grains, ensuring constant humidity conditions in the chamber.

GnuSurfTensPBS.pdf : Graphic of the surface tension $\gamma$ of diluted PBS as a function of the dimensionless PBS concentration $\kappa$, defined in the main text.

Phi5_10-4PBS5_10-2F1-100_2_10-5Lens4X1_6XFocUp140.avi : 100X accelerated PIV video of an evaporating droplet with $\kappa=5.~10^{-2}$. The focus of the camera is set approximately at the middle of the initial height of the droplet, in order to enhance the apparition of the pattern triggered by the Marangoni instability.

Filtered100XPhi5_10-4PBS5_10-2F1-100_2_10-5Lens4X1_6XFocUp140: Same video as the first one, but after image filtering, in order to give an example on what pictures the PIV analysis is actually performed.

Phi5_10-4PBS5_10-2F1-100_2_10-5Lens4X1_6X.avi : 100X accelerated PIV video of an evaporating droplet with $\kappa=5.~10^{-2}$. The focus of the camera is set directly above the solid substrate, in order to enhance the final stage of the dried pattern deposit.

Phi5_10-4PBS6_10-3F1-100_2_10-5Lens4X1_6XFocUp140.avi : 100X accelerated PIV video of an evaporating droplet with $\kappa=6.~10^{-3}$. The focus of the camera is set approximately at the middle of the initial height of the droplet, in order to enhance the apparition of the pattern triggered by the Marangoni instability.

Phi5_10-4PBS6_10-3F1-100_2_10-5Lens4X1_6X.avi : 100X accelerated PIV video of an evaporating droplet with $\kappa=6.~10^{-3}$. The focus of the camera is set directly above the solid substrate, in order to enhance the final stage of the dried pattern deposit.