No staining ! If you look closely at the first sample with the oil on it , you may see , on the unoiled part , a few white marks which are scratches . After I wiped off the oil on the sample with dishwashing soap and water on a sponge and brushed the slate using the opposite side of the sponge fairly roughly , " wah laaa " the white spots disappear ! If they do not completely disappear , then it is my understanding ( although I have not done it myself ) that one can lightly sand any significant white scratches and they will disappear .

Question: What am I explaining in this scenario ?
Answer: I am explaining how to properly rid something of scratches through sanding .I am explaining what dish - washing soap is composed of .I am explaining how to sand something to almost nothing .I am explaining what makes white marks on paintings .