Spalling is the tiny pieces of lead and steel they flies in every direction when a bullet impacts a hard surface, this can cause injury, blindness, and potentially death. ceramic and foam ballistic plates absorb the impact of bullets to reduce spalling, steel plates on the other hand if left uncoated can be your worst nightmare for a bullet strike on your body armor.
Recently I filmed a video on an AR500 steel plate that had an anti spalling coating on it. During filming we noticed there was zero spalling with pistol calibers and very little if any with the rifle calibers, compare this to steel plates that have a poor anti spall coating or none at all and the results are significant. for your life and for safety sake if you are going to use steel plates I encourage you to watch this video. make sure you are using a product that has an anti spall coating, it could save your life.