Wash them until they disintegrate.
For starching - the very few times I've done it - I put another layer of fabric over the ironing board cover - so then I can just pick it up and toss it - or put the fabrics to be starched/sized on a cookie sheet and spray them there.
I use my Big Board ironing surface as my cutting table - and my cat also "assists" - so I use a lint roller between washings to get stray stuff off the surface. Cutting lint - cat "lint"