How to Iron on a Patch

1.Lay the base item on a flat, heat-resistant surface. To ensure the item will provide a good surface for the patch, iron it first.
2.Place the patch in the position you chose. The adhesive side should be flat against the base fabric. Make sure that the patch isn't crooked.
3.Heat up an iron. Turn it to the hottest setting your fabric can tolerate.  DO NOT USE STEAM DURING APPLICATION! Make sure the "steam" option is turned off, and that your iron isn't full of water.
4.Place a thin towel over the patch. Take care not to disturb the position of the patch. The towel will protect the patch itself and the surrounding fabric.
5.Position the heated iron over the patch and press down. Hold the iron there for about 15 seconds. Apply as much pressure as you can by pressing down firmly.
6.Remove the iron and allow the patch to cool. Lift the towel and check to see whether the patch is fixed on securely by gently rubbing at the edge with a finger, trying to lift it. If it lifts up a bit, replace the towel and press it with the iron again for 10 seconds.

Caring for Your Patch
Consider sewing around the edges. For a completely secure patch, use a sewing machine or a needle and thread to secure the patch to the fabric. This greatly reduces the chances that the patch will fall off. Just a few well-placed stitches around the edges and on any fragile "points" will go a long way to ensure your creation with withstand a lifetime of wear and laundering.

Warnings
Be very careful with polyester fabrics, since applying the high heat necessary for ironing on patches can burn the fabric or cause it to get discolored.
Silk and other delicate fabrics are not good candidates for patches.