How to clean 25 yr old old discolored black slate?

Q.My Dad installed black slate on two foyers in our home about 25 yrs ago. The slate itself is discolored. Almost a yellowing. It appears(although I dont know if it was ever done-my Dad is deceased) that the sealer is what might be discolored, and just worn away in some areas? I don't know. I was told my an "old timer" neighbor, best thing to do was use an acid to strip it and start fresh. What do you recommend. They realy look awful. The grout isnt too bad. Thank you in advance. Jeff

A.Whatever you do dont use acid to strip the floor.Get some wax stripper and start there.Test one piece to see if it strips clean.read the directions wax can be tough.See if a single edge razor peels it off.If you determine its wax and you want to undertake the project read up on stripping wax.

Once the surface is free of the wax you can determine

the condition of the slate.Even if it looks pretty beat up a good quality color enhancer like mb-6 will do the trick.

If it isnt wax and a much tougher coating you may want to call a pro. Stripping tougher coating will require experience and knowledge.

Stu Rosen