After several wears (or roughhousing), a T-shirt will become stretched out. The most noticeable and upsetting part to be stretched is the neck, as the neckline is one of the primary style details scrutinized during a purchase. T-shirts get stretched because they are usually 100-percent cotton. Cotton has no elasticity and has poor recovery as a rule, but its shrinkability can be utilized to fix your wide neckline.
Things You'll Need
Iron with steam
Lay your tee on a table or other flat surface, both the front and back of the neckline visible.
Plug in and turn on the iron. Adjust the setting to full steam.
Hover the iron 1/2-inch over the left side of the front neckline of the T-shirt and apply full steam for 10 seconds.
Remove the iron and shape the neckline by hand, patting it into place, condensing the neckline inward toward the front and shoulder. The fabric of the neckline may be bunched.
Repeat Step 3. The neckline should shrink to the placement that you created. It should lie flat. If t doesn't, re-apply the steam.
Press the front left neckline flat with the heated iron (no steam).
Repeat steps 3 to 6 with both the front right neckline and the back neckline.