For small volumes:

For embroiderers in the USA: spray the hoop marks with a product called "Magic Sizing" which can be found with the spray starches at Walmart or your local grocery store, and brush or iron out the marks, depending on the fabric type.

'Magic Sizing' is a domestic silicon-based fabric conditioner used to make ironing easier - outside the USA similar products can be found amongst the spray starches but please remember to use fabric conditioner not spray-on starch which may leave white marks on dark garments.

Many customers find that simply spraying on water with a plastic mist bottle will do the trick.

For large volumes:

Spray the hoop marks with water and leave for 5-10 minutes to soak then iron flat with an industrial steam iron prior to packing