Zev,

 

Number one rule with stain removal is knowing what the stain is. If you dont know you will need to use the Unknown Stain Removal Procedure I have outlined in my book on stain removal. Here it is

 

UNKNOWN STAIN            REMOVAL PROCEDURE
 
 
The following procedure is to be used only if you have no indication of the stain type.  Be sure to test this procedure before applying it to the entire area.
 
1. Remove excess stain material from the surface by scraping with a very sharp razor blade.
 
2. Blot the stain with acetone and a clean white cloth.  If the staining material transfers to the white cloth, continue blotting until no additional stain is transferred. Proceed to step # 6   .
Sometimes blotting alone will remove the stain.(138)
 
If no stain is transferred to the white cloth proceed to step #3.
 
3.  Clean the area thoroughly with cool water and a good stone soap or neutral cleaner.  Use a white cloth to remove excess solution.  If stain is transferred to the white cloth, proceed to Step # 7 .
 
If stain is not transferred proceed to Step #4.
 
4.  Blot the area with 20%  hydrogen peroxide and a clean white cloth.  If the stain material transfers to the white cloth, continue blotting until no stain is transferred.  Proceed to Step # 8.
 
If no stain is transferred proceed to step # 5.
 
5.  Clean the area thoroughly with an iron removin g cleaner(Iron-OutÔ or equivalent).  Agitate with a soft brush or cloth and remove excess with a white cloth.  Be careful most iron removing chemicals contain acids and may etch the stone.  If stain is lighten proceed to step # 9.
 
If stain is not changed by this method proceed to step # 10.
 
6.  Apply a poultice using diatomaceous earth or equivalent powder and one of the following solvents(Mineral Spirits, Toluene, Methylene chloride).  Several poultice may be needed.&nb sp; Use only one solvent type.  Do Not mix solvents. Continue to poultice until stain is removed. If stain is not removed or lightened after five attempts proceed to step #10.

7. Apply a poultice of diatomous earth or equivalent powder and an alkaline stone cleaner or heavy duty neutral cleaner.  Several poultices may need to be applied.  Continue to poultice until stain is removed. If stain is not removed or             lightened after five attempts proceed to step #10.
 
 
8. =2 0Apply a poultice of diatomaceous earth or equivalent and 20% hydrogen peroxide.  Do not use clay or fuller earth powders with hydrogen peroxide.  If stain is difficult to remove, re-poultice using 50% hydrogen peroxide.  Several poultices may need to be applied.  Continue poulticing until stain is removed. If stain is not removed or lightened after five attempts proceed to step #10.
 
9.  Apply a poultice with diatomous earth or equivalent and an iron removing chemical(Iron-OutÔ or equivalent).  Continue poulticing until stain is completely removed.  Re-honing and/or      re-polishing may be necessary on marble.  If stain is not removed or lightened after five attempts proceed to step # 10.
 
 
10.  If stain is not removed , chances are it has become permanently set or it is part of the stone.  Replace the stone or live with the stain.  A throw rug works real well here.