Washing by hand is recommended.
However, we know most parents are too busy for that. We personally wash our bibs on the delicate cycle with cold water and then tumble low on cool. Using high heat may cause fabrics to shrink.
As these bibs are quilted, the fabric will crinkle over time. This is good. You can iron bibs on cool if they bend slightly in the wash. However, just like an old quilt has beautiful crinkles, a crinkled bib is even better. Every bib is prewashed once before arriving to you in order to start the crinkle process.