onArmorTick(...)

@Override
public void onArmorTick(World world, EntityPlayer player, ItemStack itemStack) {
    float absorption = player.getAbsorptionAmount();
    float limit = 10.0f;
    if (this.armorType == 1) {
        if (absorption < limit) {
            if (player.ticksExisted % 80 == 0) {
                absorption += (limit - absorption);
                player.setAbsorptionAmount(absorption);
            }
        }
    }
}