Preparing a Non-Toxic Water-Repellent Preservative

CSI Division
Division 10 - Specialties
Section
Preservative Treatment
Last Modified

Technical Procedures Disclaimer

Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.

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We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.

PART 1–GENERAL

1.01 SUMMARY

  1. This procedure includes guidance on preparing a water-repellent preservative that is relatively environmentally friendly.  It is derived from a formula provided by the United States Department of Agriculture Forest Products Laboratory.

PART 2–PRODUCT

2.01 MANUFACTURERS

  1. United States Department of Agriculture Forest Products Laboratory

2.02 MATERIAL

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. Mineral spirits:
    NOTE:  MINERAL SPIRITS SHALL BE CLEAN AND COLORLESS SO THAT IT WILL NOT ADVERSELY AFFECT THE TEXTURE OR DURABILITY OF THE STAIN.
    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 miner al 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.
    6. Pure steam distilled turpentine is the legacy product that would have historically been used for a preservative mixture of this type, and it may be directly substituted for mineral spirits.  The primary difference between the two is that mineral spirits is a petroleum product with a low cost, and turpentine is a wood product with a higher cost.
  2. Paraffin wax
  3. Boiled linseed oil:
    1. Boiled linseed oil shall be used rather than raw linseed oil as raw linseed oil does not dry and will leave a sticky residue that is difficult to maintain with paint.
    2. The linseed oil shall be fresh and directly from a sealed container so that there will be no unintended impacts to the texture or durability of the paint coating applied to it.
  4. Clean, clear water

2.02 EQUIPMENT

  1. Double boiler (this is a device normally utilized for heating food or doing canning, using  an external vessel (pot) filled with water, and an internal vessel suspended in the water (another pot) that is filled with the product to be warmed.  This insures that the product to be warmed cannot burn or attain a spot-temperature higher than the boiling point of water.)
  2. Stiff bristle brush

PART 3–EXECUTION

3.01 ERECTION, INSTALLATION, APPLICATION

NOTE:  THIS WILL MAKE 5 GALLONS OF SOLUTION.

  1. Melt (1 lb.) paraffin in double boiler being careful not to get it too hot as it can ignite.  Temperature should range between 80 and 100 degrees F.
  2. Allow to cool to about 70 degrees F before adding the preservative mixture.
    CAUTION:  FUMES ARE HIGHLY TOXIC WEAR PROTECTIVE CLOTHING INCLUDING GOGGLES WORK OUTSIDE USE AN ORGANIC VAPOR RESPIRATOR.
  3. Add (3 gallons) boiled linseed oil and (1 gallon) mineral spirits.
  4. Apply the mixture at 70 degrees F to 80 degrees F.  Below 40 degrees F the paraffin is not sufficiently liquid and the material cannot penetrate.  Above 80 degrees F the mixture dries too fast and will not achieve sufficient penetration.

 

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Last updated: Jul 20, 2021
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