[1.8] Using ISpecialArmor without Armor material

I'm stucked now for a while, cause I don't know how I have to use the ISpecialArmor getProperties() to let the armor work like it has a armor material, that defines the damage reduction. I've tried this, but it doesn't seem to work when I compare it to normal armor.

@Override
    public ArmorProperties getProperties(EntityLivingBase player, ItemStack armor, DamageSource source, double damage, int slot) {
        if(armor.getTagCompound() != null) {
            ArmorValues values = ArmorValues.readFromNBT(armor);
            return new ArmorProperties(0, values.getResistance() / 25.0D, values.getResistance());
        }
        return new ArmorProperties(0, 0, 0);
    }

The problem why I can't use a armor material is, that the armor is different in the damage reduction depending on the crafting.