I don't know of any that would interfere with your painting of that item. I myself use Lugol'sIodine 5% solution and have painted different surfaces of my body with excellent results. Most people here are using the Liquid Lugol's at the 5% solution. They also have a 2% but I don't know how well it works, since I have not used it personally.
If the area stings too much for you, you can mix the Iodine drops into some good oil like sunflower, olive, coconut, avocado, or almond oil and apply. I like to mix the oil and Iodine and apply to my face and neck. I also have painted my neck and thyroid with just the Iodine with no problems.