Do you ever wonder when you're crocheting a hat, you follow a pattern only for it to say use acrylic yarn? That's okay. Every time we download patterns such as a hat, scarf, etc., we like to tweak the design. You can use a bulky yarn with the Ombretta hat. The only difference is because it's a thicker yarn, you will need to use a larger crochet hook and crochet fewer rounds. To keep the proportions identical, you must follow these steps. I would like to recommend a size P 19(15mm) crochet hook.