Once upon a time there was a girl who had searched high and low for the perfect black silk t-shirt. Finding nothing suitable in the shops, she had resigned herself to attempting to draft a pattern from the perfect non-black silk tee she already loved.
Then she found a kimono t-shirt pattern that fit her like a princess’s shoe. Excellent, the girl thought, I can use that to make a perfect black silk t-shirt. She found beautiful black silk at the fabric shop (after only a minor incident in which the shopkeeper charged the girl for twice the amount she had bought) and cut it out in a larger size than she had made previously. For the girl thought she was getting to be a fairly good sewer and knew that the size of the stretch jersey she had made before would be too small in the beautiful black silk.
She sewed the shirt carefully, with a very sharp needle, using her new-found French seaming skills and finishing the openings with red bias tape (she could hear her mother saying usually one would line the openings in the same colour as the main fabric but she liked the flashes of red against the black).
After sewing the shoulders and the sleeves and the side seams, the girl tried the beautiful black silk t-shirt on. It was so tight across the shoulders and bust she very nearly couldn’t get it off again.
The girl gnashed her teeth and cursed her foolhardiness.
Then she finished the neckline and the hem and hoped it would fit one of her friends.
Moral of the story: when switching up fabrics, make a muslin first.