I bought some new jersey sheets at Linens ‘n’ Things this weekend. (I like jersey sheets because they’re much softer than regular sheets and half the cost.) Anyway, I was replacing some cheaper all-cotton jersey sheets that had shrunk and pilled in the year or so that I had them. My allergist said I’m supposed to wash my bedding in hot water once a week. The new sheets are 90% Modal and 10% cotton. The instructions say to wash them in cold water. They’re supposed to be more resistant to pilling and shrinking than cotton sheets. How will they hold up if I wash them in hot water? How about if I bleach them? They were $50 and I don’t want to ruin them in the second wash.
The most important properties of Micro Modal: Micro Modal 100% pure and ideal in blends
This describes 100% Micro Modal, not the 90/10 cotton blend you have.
I don’t see how adding 10% cotton would necessitate a cold wash.
From a quick look at the site, it appears Lenzing is marketing Modal as an intermediate between cotton and silk. Perhaps the “cold wash” in your care instructions has more to do with getting people to think of the stuff as silk than it does the requirements of the fabric.
If I’d purchased these sheets, I’d be willing to try a hot wash on them. I’d let the next person down the block be the first to try bleaching them.
My (very) limited experience with Modal sheets is that they don’t seem to be particularly colorfast. Maybe that’s why the instructions say cold water?
In any event, if you wash your white underwear with your new blue Modal sheets, don’t be surprised if you end up with light blue boxers. It’s happened before…
Well, since they’re white, I’m not too worried about colorfastness. 
I was just concerned that bleach might weaken the fiber or something.
I can definitely see the comparison between Modal and silk. It’s very soft material. I can’t wait to sleep on them tonight.
60ºC = 140ºF, and my water heater’s set to 130ºF, so it sounds like they’ll be just fine in hot water. Thanks!
My secret to washing all cotton sheets in hot water without excess shrinking is to buy queen sized white sheets for my full bed. I wash and dry them right out of the packaging and put them on the bed right when the buzzer goes off on the dryer. They feel even softer than in the store.
I have 100% modal sheets. I’ve washed them in hot water with bleach a few dozen times and they are still holding up nicely. I changed to modal from jersey for the same reasons as you. I really like them except for two things: first they are thinner than jersey cotton sheets so I like to double them up, and second they don’t let sweat escape quite as readily as cotton.