Removing Oil and Fat Stains from Marble

PREFACE

The cleaning or removal of stains from stone may involve the use of liquids, detergents or solvents which may run off on adjacent material, discolor the stone or drive the stains deeper into porous stones. Use the products and techniques described here only for the combinations of dirt/stain and stone specified.

PART 1–GENERAL

1.01 SUMMARY

1. This specification provides guidance on poulticing marble stained with oil and fat containing substances such as oil-based paints, lipstick, butter, cream, milk, peanut butter, hand lotions, mustard and deposits bound to the surface by or consisting entirely of oils, grease and/or bituminous products.

2. Oil stains are usually light brown or yellow in color.

3. Most oil based products are composed of some material, often pigmented, suspended in an oily vehicle. When such a product is applied to a surface, the oil tends to penetrate into porous substrates such as masonry. The pigmented matrix may rest on the surface, while the oil is absorbed into the stone, generally causing a darkening effect.

4. Poulticing is the most effective means of removing oil and fat stains from marble. A solvent is used to dissolve the oil, and a medium is applied to the surface which absorbs the oil, drawing it to the surface and into the poulticing medium as it dries.

   1. Stain removal by conventional washing is usually impossible. The pigmented matrix may be removed by scraping or washing; however, the dark oil stains are usually quite apparent, especially on white or light colored stone.

   2. Abrasive cleaning techniques are INAPPROPRIATE and NOT RECOMMENDED, as they result in excessive loss of surface material and altered texture. Furthermore, abrasive cleaning will not remove deeply penetrated oil staining.

   3. Steam cleaning is also INAPPROPRIATE and NOT RECOMMENDED for this type of stain removal as the steam heat reduces the viscosity of the oil and drives it deeper into the stone, thereby spreading the stain.

5. Read “General Project Guidelines”. These guidelines should be reviewed prior to performing this procedure and should be followed, when applicable, along with recommendations from the Regional Historic Preservation Officer (RHPO). These guidelines cover the following sections:

   1. Safety Precautions

   2. Historic Structures Precautions

   3. Submittals

   4. Quality Assurance

   5. Delivery, Storage and Handling

   6. Project/Site Conditions

   7. Sequencing and Scheduling

   8. General Protection (Surface and Surrounding)

6. See also:

   1. “Removing Unknown Stains from Marble Using a Poultice”

   2. “Marble: Characteristics, Uses and Problems”

PART 2–PRODUCTS

2.01 MANUFACTURERS

ProSoCo, Inc.

Lawrence, KS 66117

1-800-255-4255

2.02 MATERIALS

NOTE: Chemical products are sometimes sold under a common name. This usually means that the substance is not as pure as the same chemical sold under its chemical name. The grade of purity of common name substances, however, is usually adequate for stain removal work, and these products should be purchased when available, as they tend to be less expensive. Common names are indicated below by an asterisk (*).

1. Acetone (C3H6O):

   1. A volatile fragrant flammable liquid ketone used chiefly as a solvent and in organic synthesis and found abnormally in urine.

   2. Other chemical or common names include Dimethyl ketone; Propanone

   3. Potential Hazards: VOLATILE AND FLAMMABLE SOLVENT

   4. Available from chemical supply house or hardware store.

2. -OR-

   Mineral Spirits:

   1. A petroleum distillate that is used especially as a paint or varnish thinner.

   2. Other chemical or common names include Benzine* (not Benzene); Naphtha*; Petroleum spirits*; Solvent naphtha*.

   3. Potential Hazards: TOXIC AND FLAMMABLE.

   4. Safety Precautions:

      1. AVOID REPEATED OR PROLONGED SKIN CONTACT.

      2. ALWAYS wear rubber gloves when handling mineral spirits.

      3. If any chemical is splashed onto the skin, wash immediately with soap and water.

   5. Available from construction specialties distributor, hardware store, paint store, or printer’s supply distributor.

-OR-

Commercial cleaner such as “Stand Off Oil and Grease Stain Remover” (ProSoCo, Inc.), or approved equal.

2. White absorbent material (molding plaster, untreated white flour, white tissue, paper towels, powdered chalk, talc, baking powder, baking soda, fullers earth or laundry whiting), or a commercial absorbent material such “Stand Off Poultice Powder” (Prosoco), or approved equal.

3. Mineral water

4. Plastic sheeting

5. Clean dry towels for blotting the area after treatment

2.02 EQUIPMENT

1. Glass or ceramic container for mixing the solution

2. Wooden utensil for stirring the ingredients

3. Wood or plastic spatula

4. Masking tape

PART 3–EXECUTION

3.01 EXAMINATION

Examine the marble surface CAREFULLY to determine the cause of staining before proceeding with any cleaning operation.

3.02 ERECTION, INSTALLATION, APPLICATION

NOTE: BEGIN CLEANING BY USING THE GENTLEST METHOD POSSIBLE. TEST CLEAN A SMALL AREA BEFORE ATTEMPTING TO CLEAN LARGE AREAS TO DETERMINE APPROPRIATE DWELL TIMES AND NUMBER OF APPLICATIONS NECESSARY TO ADEQUATELY REMOVE THE STAIN.

1. Apply a poultice:

   1. Rinse the area to be treated with mineral water.

   2. Mix the acetone or mineral spirits in a glass or ceramic bowl. Use an amount adequate to fully cover the affected area.

   3. Thoroughly moisten the stained surface with this liquid. Be sure to dampen well beyond the stain.

   4. Mix the remaining liquid with the white absorbent material to form a paste the consistency of oatmeal or cake icing. (Approximately one pound of paste is needed for every square foot of surface area to be treated).

   5. Using a wooden or plastic spatula, apply the paste to the stained surface in layers no more than 1/4 inch thick. The poultice should extend well beyond the stain to prevent forcing the stain into previously clean stone.

   6. Check the coating for air pockets or voids.

   7. Cover the poultice with plastic sheeting and seal with masking tape.

   8. Let set for 48 hours (unless otherwise specified).

   9. After set period, dampen the poultice with mineral water.

   10. Remove the poultice with a wooden or plastic spatula to avoid scratching the surface.

   11. Again, thoroughly rinse the cleaned area with mineral water, blot with clean towels and allow the surface to dry.

   12. Once the surface has dried completely, check for remaining residue and repeat the treatment if necessary.

-OR-

2. Apply a commercial cleaner following manufacturer’s instructions.