Pre-soak in the tub.
Sometimes, home washing machines can get too claustrophobic for heavier weight fabrics. Creases and folds present when the fabric goes into the wash may lead to inconsistent dye runs and white lines throughout the piece. Instead of washing, try soaking your fabric in a cold water bath and hanging to dry. This will lessen indigo dye loss and still help to shrink the fabric before use.
Remember to Floof!
Please note that any non-stretch fabric over 11.5oz is best left out of the washing machine. If you do plan on machine washing your 11oz or lighter denim fabric (and you totally can!) open up your yardage and *floof* to minimize the amount of creases and crinkles as much as possible. nfold your whole piece, flick it open a few times to fully unfurl, and mind the crinkles and creases you are creating as you lower it into your washing machine. This is a very important step! A good floof can save you from large crease marks that span your entire yardage. Remember to use a cold water wash and minimal amount of detergent, we want to keep as much indigo (or other dyes) in as possible.
Try washing each piece individually. This will allow the fabric enough space to stay open and unfurled throughout the entirety of the washing cycle, allowing for minimal creases and fold lines in the final washed yardage.
Iron out any noticeable marks
If you notice any areas where the dye has not dispersed to your liking, try ironing the wrong side of the spot when the fading has occurred while the denim is still damp. Use a high heat for 100% cotton or a low heat for stretch fabrics, and press with lots and lots of steam. Then hang to dry (never tumble dry as it fades the dye quicker!)