If you accidentally shrink a wool shirt, there is a chance to try and loosen it back up using a few methods. However, keep in mind that the success of these methods can vary based on the extent of shrinkage and the specific type of wool used in the shirt. Here are some steps you can try:
Soak in lukewarm water: Fill a basin or sink with lukewarm water and add a small amount of hair conditioner or baby shampoo. Submerge the shrunken wool shirt in the water and gently swish it around. Let it soak for about 30 minutes to allow the fibers to relax.
Gently stretch: While the shirt is still wet, carefully stretch it back to its original shape. You can do this by pulling the fabric gently and evenly in all directions. Avoid using excessive force, as this could damage the fabric.
Use towels for reshaping: Lay the wet wool shirt on a clean towel and gently roll it up in the towel to remove excess water. Then, carefully reshape the shirt to its original size and dimensions. You can lay it flat on another dry towel, using the original size as a guide.
Blocking method: For more stubborn shrinkage, you can try the "blocking" method. Lay the damp wool shirt on a flat surface (a clean, dry towel or foam mat). Gently stretch and shape the shirt to its original size and pin it in place using rust-resistant T-pins. Allow it to dry completely in this stretched state.
Commercial wool relaxer: There are commercial products available specifically designed to relax shrunken wool garments. These products may be worth trying if the above methods don't yield satisfactory results.
Remember that wool is a delicate fabric, and aggressive stretching or the use of hot water can cause irreparable damage. Always be gentle and patient with the process. Additionally, there is no guarantee that the wool shirt will return to its original size completely, especially if the shrinkage was severe.
As a preventive measure in the future, it's essential to follow the care instructions on the garment's label carefully. Avoid using hot water and agitation (such as vigorous machine washing) with wool clothing to minimize the risk of shrinkage.