Acrylics dry dark.
Now how beautiful the painting or color you’ve just added, as the acrylic dries, the paint color darkens. I find myself constantly brightening my clouds and especially the sails of my tall ships.
The good news is acrylics dry quickly so it isn’t a long wait to discover just how much darker your dry painting is. So be prepared to go back over highlights 3-4 time until you achieve the brightness you’re seeking.