Our fabrics are test washed for shrinkage by the manufacturer. You can expect roughly 4 - 5 % shrinkage.

Ideally wash bright colours inside out on a 30 degree wash.

Some testers have told me that they wash their brights on a cool wash with a few tablespoons of table salt added. More info can be found here: 

https://home.howstuffworks.com/home-improvement/household-hints-tips/cleaning-organizing/how-to-brighten-colors-while-washing-clothes1.htm

We don't recommend tumble drying as the heat can cause fading. Line dry and a cool iron (if required).