To ship curtains they need to be folded so that they can ship in boxes. This of course will cause the material to have folds when it arrives and you unpack it. These wrinkles are more noticeable in the winter when temperatures are cold and the material is stiffer.
These folds will relax overtime giving you a smooth curtain. How fast that happens depends on how warm your environment is and the size of your curtain. If you need to smooth the curtain out ASAP then you can perform the following procedures below.
Hair Dryer Method
Lay the curtain on a flat surface. Start by spreading out the curtain on a flat surface, such as a wood table, a clean floor, or a clean counter. If you are trying to remove folds from a large curtain, you may need to work in sections, moving the section on to the flat surface to remove the folds.
a. You may lay down a piece of cardboard or a clean towel underneath the curtain to protect the surface from heat if you are concerned about damaging the surface. You could then move the piece of cardboard underneath each section as you apply heat to it.
Set the hair dryer to the low heat setting. Use a low heat setting so you do not risk melting or damaging the vinyl curtain. If you are using an iron, select the low heat setting so you do not risk scorching the curtain
Hold the hair dryer or iron ½ - 1 inch from the curtain. Make sure you keep the hair dryer or iron hovering over the curtain and do not place it directly on the curtain. Holding it ½ - 1 inch from the curtain should be close enough for the heat to straighten out the folds.
Run the hair dryer or iron over the folds slowly in small circular motions. Let the dryer hover over the fold for a few seconds, shaking the hair dryer or iron slightly. This will let the hot air disperse over the vinyl without burning it.
Remove the folds in sections. Focus on one section of the curtain at a time, hovering the dryer or iron over the folds. Once one section is flattened, move on to the next section.
It may take a few minutes for the fold to straighten out so be patient and work slowly. You may place your hand on the fold lightly to check that the curtain is not too hot or sticky as you remove the folds. You may need to let the curtain sit out flat and cool once you have removed all the folds. You can then hang it up and use it.