Refinishing A Radiator

Procedure code:
1575001S
Source:
Ohj - May 1986 And September/October 1988
Division:
Mechanical
Section:
Heat Transfer
Last Modified:
08/10/2016

NOTE:  Refinishing a radiator is a tedious and time-consuming job. If other work requires the removal of the radiator, it is usually better to disconnect and remove the radiator at that time for refinishing off site.  If, however, it is not necessary to remove the radiator, it is probably better to refinish it in situ using one of the methods described below, because removing and reinstalling a radiator is often difficult.

Before undertaking any project involving paint removal, applicable state and federal laws on lead paint abatement and disposal must be considered and carefully followed.  State and federal requirements may affect options available to owners on both paint removal and repainting.  These laws, and any requirements prohibiting volatile organic compounds (VOCs), should be requested from the (from Preservation Brief 28, "Painting Historic Interiors.")  Environmental Protection Agency quality.

PART 1---GENERAL

1.01 SUMMARY

  1. This procedure includes guidance on removing an existing coating from a radiator and refinishing it by either repainting, rebronzing, or polychroming
    1. Bronzing is a decorative method of painting radiators using a mixture of bronzing liquid and bronzing powder to achieve a metallic surface appearance.
    2. Polychroming is a decorative method of painting radiators that involves the use of two and three color paint schemes to highlight the ornament.
  2. Safety Precautions:
    1. PAINT BEING REMOVED MAY CONTAIN LEAD.  ALL WORKERS MUST WEAR PROTECTIVE CLOTHING (INCLUDING HAIR), GOGGLES, RUBBER GLOVES AND RESPIRATORS WITH HIGH EFFICIENCY PARTICULATE AIR FILTERS (HEPA).
    2. No food or drink shall be allowed near any work station to prevent contamination from paint, paint chips, dust or chemical removers that contain lead and other toxic substances.
    3. Protective clothing shall be removed at the end of each day and kept at the site to prevent workers from tracking dust and paint chips to other parts of the site or to their homes.
    4. Wash hands and face often, especially before eating and at the end of the day.
    5. All waste material shall be collected at the end of each work day and disposed of consistently with local environmental regulations.  It is considered Hazardous Waste.
  3. See "General Project Guidelines" for general project guidelines to be reviewed along with this procedure.  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)
      These guidelines should be reviewed before performing this procedure and should be followed, when applicable, along with recommendations from the Regional Historic Preservation Officer (RHPO).

PART 2---PRODUCTS

2.01 MANUFACTURERS

  1. American Brush Co.
    (Radiator Brushes and Paints)
  2. Benjamin Moore, Co.
  3. Glidden Coatings & Resins
  4. Johnson Paint Co., Inc.
    (Paints and Bronzing Liquids and Powders)
  5. Consumer Products Group
  6. PPG Industries, Inc.
  7. The Sherwin Williams Co.

2.02 MATERIALS

  1. Commercial paint remover, such as "Citristrip" (Specialties Environmental Technologies, Inc.), "Safest Stripper" (3M), or approved equal.
  2. Zinc-rich oil-based primer such as zinc chromate or red iron oxide-linseed oil paint:
    1. Good for use on partially deteriorated surfaces.
    2. Provides protection where moderately corrosive conditions exist. 
      -OR-
  3. Modern alkyd paint:
    1. Should only be applied to clean, non-corroded surfaces.  
    2. Provides protection where there are only mildly corrosive conditions, and where normal humidity and condensation ranges exist, i.e., a residential or office environment.
      NOTE:  CONSULT THE PAINT MANUFACTURER FOR APPROPRIATE
      CHOICE FOR USE ON METAL.  
  4. Oil-based paint:  Use a non-metallic flat paint.
     -OR-
  5. Metallic oil-based paint (ONLY IF MAXIMUM HEAT TRANSFER IS NOT AN IMPORTANT FACTOR)
    1. Any oil-based top coat, made to be used with the primer, may be applied as the top coats.  
    2. Use paint from the same manufacturer for both prime and top coats, and make sure they are made to work together.
  6. Bronzing Supplies:
    1. Bronzing powder (the pigment):  Available in a wide range of metallic tones.
    2. Bronzing liquid (the vehicle):  Oil-based.

2.03 EQUIPMENT

  1. Radiator Brushes (American Brush Co.), or approved equal:
    1. One with long handle to reach between the radiator fins
    2. One with an offset handle for reaching behind the radiator
    3. 1-1/2" camel's hair brush
    4. A wide, flat, soft brush
    5. Stiff wire brush
  2. Goggles
  3. Face mask
  4. Drop cloths
  5. Masking
  6. Ball peen hammer

PART 3---EXECUTION

3.01 PREPARATION

  1. Before recoating, determine what role the paint or coating is to provide.
    1. If maximum heat transfer is important, use a non- metallic coating such as a flat, black paint (a flat finish surface radiates heat better than a shiny one).
    2. NOTE:  OIL PAINTS GENERALLY DO NOT REDUCE HEAT TRANSMISSION IN A RADIATOR AND ARE SUITABLE FOR USE WHEN MAXIMUM HEAT TRANSFER IS AN ISSUE.
    3. NOTE:  AVOID USING METAL BRONZE PAINTS OR ANY PAINTS CONTAINING METAL PARTICLES.  THESE TEND TO REDUCE HEAT TRANSMISSION IN A RADIATOR.
  2. If aesthetics are important and potential heat loss is acceptable, bronzing may be a suitable alternative.

3.02 RECTION, INSTALLATION, APPLICATION

  1. Strip existing coating from the radiator.
    CAUTION:  PAINT MAY CONTAIN LEAD.  FOLLOW ALL SAFETY REGULATIONS REQUIRED BY STATE AND FEDERAL LAWS ON LEAD PAINT ABATEMENT AND DISPOSAL.
    1. Mechanical Method:  This method is typically the most commonly used and the most successful.
      1. Knock off loose paint and scale using a stiff wire brush.  Special radiator brushes are also available (see Part 2 above).
      2. Tap the radiator repeatedly with a ball peen hammer to loosen the paint bond on tougher areas.
      3. Vigorously brush the radiator again with a stiff wire brush to remove remaining paint.  A wire brush on a rotating drill may be used if the worker is protected and working in an isolated area
    2. Chemical Method:  This method is typically time- consuming and messy.
      1. Apply a NON-methylene chloride paint stripper using a stiff bristle brush.
      2. Cover the stripper with strips of plastic wrap to prevent the solvents in the stripper from evaporating.
      3. Allow stripper to remain on the surface for length of time as recommended by manufacturer.
      4. Remove plastic wrap and remove sludge with small chisels and brushes.
      5. Rinse the surface with mineral spirits and allow to dry.
    3. Heat Method:  This method is not very effective in removing coatings from a radiator.  Heat from the heat gun gets absorbed into the cast iron before it has time to soften the paint.
    4. Remove the radiators and have them stripped off- site by immersion-tank stripping or sandblasting.
      NOTE:  REMOVAL AND REINSTALLATION OF A RADIATOR IS VERY DIFFICULT.  THIS METHOD SHOULD ONLY BE USED IF REMOVAL OF THE RADIATOR IS REQUIRED FOR OTHER PURPOSES.
      1. Drain the hot water system and disconnect the radiator.
      2. Remove the radiator and send off-site for stripping and recoating.
  2. Refinish Radiator:
    1. Painting:  
      CAUTION:  DO NOT USE WATER-BASED PAINTS ON CAST IRON.  THEY MAY CAUSE THE METAL TO RUST.
      1. Prime paint the radiator using a brush for complete even coverage.
      2. Brush apply two top coats of the selected oil- based paints.
    2. Bronzing:
      1. Prime paint the radiator using spray auto-body paint.  Auto-body paint is appropriate for several reasons:
        1. It can withstand radiator heat.
      2. It is sandable, enabling one to hide small imperfections in the metal.
        1. It is available in light grey and other colors suitable as a base for bronzing.
        2. Sand the entire surface with fine-grit sandpaper.
        3. Brush sandpaper dust from the surface using a stiff bristle brush.
        4. Mix bronze metallic paint in a bucket.  Mix1/2 lb. bronzing powder with 2 cups bronzing liquid.  Add the powder to the liquid to achieve a paint the consistency of cream.
          NOTE:  1 QT. BRONZING LIQUID TYPICALLY COVERS 250-300 S.F.
        5. Brush mixture onto the radiator carefully using several soft bristle brushes as required (see brushes under Part 2 above).
          NOTE:  BE SURE TO USE SOFT BRISTLE BRUSHES.  A STIFF BRUSH MAY INHIBIT ACHIEVING A SMOOTH METALLIC FINISH WHEN APPLYING THE BRONZE PAINT.  ALWAYS BRUSH IN THE SAME DIRECTION
    3. Polychroming:  Typically used on ornamental radiators for highlighting special ornamental portions.
      1. Prime paint and sand the radiator (see Section 3.02 B. 2. a-c above).
      2. Using brushes, paint the entire radiator the color desired for the ornament and allow to dry.
      3. When dry, paint the entire radiator the color desired for the background.
      4. While the second coat of paint is still tacky, wipe a clean cloth or sponge over the ornament ONLY to expose the paint color below.
      5. The ornament may also be hand painted if desired.

END OF SECTION

Last Reviewed 2016-08-10