Removing Paint From Wrought Iron, Cast Iron And Steel Using Chemical Methods
- Procedure code:
- Developed For HSPG (NPS - SERO)
- Metal Materials
- Last Modified:
REMOVING PAINT FROM WROUGHT IRON, CAST IRON AND STEEL USING CHEMICAL METHODS
TAKE SPECIAL CARE TO PROTECT ALL ADJACENT MATERIALS, FROM DAMAGE BY SPLASHING OR RUN OFF THAT MAY CONTAIN CLEANING OR STRIPPING PRODUCTS AS WELL AS PAINT, FINISHES AND SOILING REMOVED FROM TREATED SURFACES. DO NOT USE THIS PROCEDURE ON METALS OTHER THAN THOSE SPECIFIED. REVIEW MANUFACTURER'S CAUTIONS AND APPLICABLE FEDERAL, STATE AND LOCAL REGULATIONS GOVERNING PRODUCT USE AND CONTROL OF HAZARDOUS MATERIALS BEFORE UNDERTAKING WORK INVOLVING REMOVAL OF PAINTS AND COATINGS; ADJUST PRODUCT SELECTION AND METHODS ACCORDINGLY. TEST MILDEST, MOST ENVIRONMENTALLY BENIGN FORMULATIONS FIRST BEFORE PROCEDING TO STRONGER CHEMICALS AND HARSHER METHODS.
A. This procedure includes guidance on chemically removing
paint from wrought iron, cast iron and steel. These
metals should be repainted immediately following paint
removal in order to prevent exposure to the atmosphere
and subsequent corrosion.
B. For information on painting and coating these materials
see 05010-13-S "Primers and Paints for Wrought Iron, Cast
Iron and Steel", 05010-18-R "Applying a Sacrificial
Coating to Wrought Iron, Cast Iron and Steel", and
09900-07-S "General Guidelines for Painting Exterior and
C. Chemical methods as used herein shall apply to the use of
commercial chemical paint strippers and rust removers.
D. There are several causes for paint failure on metal.
Excess moisture can cause rusting. As metal rusts, the
rust expands breaking the bond between the metal and the
paint. Inadequate or improper surface preparation can
interfere with the proper bonding of the new paint. The
wrong primer can cause anything from pitting of the metal
surface to peeling of the new paint.
E. It is not necessary to remove all previous coats of paint
1. they are adhering soundly,
2. the new painting system is compatible,
3. important design details are not being obscured by
the paint layers.
F. An archives of the paint history of the building is to be
maintained. This is to include the paint samples taken
during research, samples of the new paint colors and the
manufacturers technical information.
G. Safety Precautions:
1. No food or drink shall be allowed near any work
station so as to prevent contamination from paint,
paint chips or paint dust which may contain lead
and other toxic substances.
2. Paint being removed most likely will contain lead.
All workmen must wear protective clothing,
(including hair), goggles and respirators with
3. Protective clothing shall be removed at the end of
each day and kept at the site to prevent workers
from taking 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 in a manner
consistent with local environmental regulations.
It is considered Hazardous Waste.
6. Work area shall be sealed to prevent the spread of
paint dust and debris beyond the work site.
7. After paint removal is complete, all areas around
the building shall be cleaned of all paint dust and
debris, and such debris shall be properly disposed
of in a manner consistent with local environmental
H. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
I. For additional information on cast and wrought iron see
the following procedures:
1. 05010-04-S, "Cast Iron: Characteristics, Uses and
2. 05010-11-S, "Wrought Iron: Characteristics, Uses
3. 05010-01-S, "Checklist for Inspecting Cast Iron
A. For Chemical Paint Removers:
1. ProSoCo, Inc.
800/255-4255 or 913/281-2700
Availability: Through contractors licensed by
2. Star Bronze Co.
P.O. Box 2206
Alliance, OH 44601
3. Savogran Company
800/225-9872 or 617/762-5400
4. Deidrich Technologies
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, but the grade of
purity of common name substances, is usually adequate
for stain removal work, and these products tend to be less expensive. Common
names are indicated below by an asterisk (*).
A. Chemical Paint/Lacquer Removers:
1. Manufacturer's standard thixotropic
formulation for removing paint coatings from
ornamental metal work. Review manufacturer's literature to identify least hazardous products that may be effective for initial testing. Examples include: "Envirestrip" (Diedrich Technologies), "EnviroKlean Safety Peel 1" (Prosoco, Inc.), Zip Strip 2 (Star Bronze Co.) and "Biodegradable Stripeeze" (Savogran Co.)
2. Semi-paste, water rinsing, nonbenzol remover such
as "Strypeeze Semi-Paste" (Savogran Company), or
a. Characteristic orange color.
b. Will work on both latex and oil-based paints,
lacquers and varnishes.
c. Cling well to round or vertical surfaces.
d. Form an anti-evaporative film as they dry.
e. Clean-up by either washing or scraping off.
All traces must be removed and a neutral pH
achieved before repainting.
f. Use if milder formulations are not effective.
3. Non-flammable, heavy bodied, methylene-chloride
based remover such as "Super Strip Non-flammable",
"Zip-Strip" (Star Bronze Co.), or approved equal.
a. Good for interior use because they are non-flammable.
b. Will soften oil-based paints, lacquers,
varnish and synthetic baked finishes.
c. Because they are so heavy bodied they will
cling to vertical and irregular surfaces.
d. Use if milder formulations are not effective.
4. Non-flammable, water rinsing, liquid remover such
as "H2O Off", or approved equal: Available from
paint supply store.
a. Methylene-chloride based strippers excel in speed and effectiveness but produce toxic fumes and waste, limiting (in some locations prohibiting) their use. Test milder, non-hazardous formulations first.
b. Will soften oil-base paints, varnish, and
synthetic baked finishes.
c. Will not work on vertical surfaces. Good for
5. Liquid benzol remover such as "Kutzit", or approved
equal: Available from paint supply store.
a. HIGHLY FLAMMABLE AND TOXIC. WEAR PROTECTIVE CLOTHING. USE IN WELL VENTILATED AREA, DO NOT USE NEAR FLAME, SPARKS, OR HEATERS.
b. Will remove oil-based paint, lacquer. varnish
and synthetic baked finishes.
c. Work well on flat surfaces. Work quickly.
B. Chemical rust removers, such as "Navel Jelly", or
C. Cornstarch or fumed silica to further thicken chemicals
so they will adhere to vertical surfaces.
D. Liquid Strippable Masking Agent: Manufacturer's standard
liquid, film forming, strippable masking material for
protecting glass, and polished stone surfaces from
damaging effect of acidic and alkaline cleaners, such as
"Sure Klean Acid Stop" (ProSoCo, Inc.), or approved
E. Mineral Spirits: (To remove chemical residue)
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*;
3. Potential Hazards: TOXIC AND FLAMMABLE.
4. Safety Precautions:
a. AVOID REPEATED OR PROLONGED SKIN CONTACT.
b. ALWAYS wear rubber gloves when handling
c. 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.
F. Phenolphthalein: Used to test pH of a surface after
stripping with chemicals or any alkaline product.
Available at some drug stores or chemical supply houses.
G. Trisodium Phosphate and TSP Substitutes
DUE TO ENVIRONMENTAL HAZARDS OF PHOSPHATES, TSP IS PROHIBITED IN SOME LOCATIONS. USE ONLY AS NEEDED AFTER TESTING ALTERNATIVES FOR CLEANING EFFECTIVENESS.
1. Strong base-type powdered cleaning material sold
under brand names.
2. Other chemical or common names include Sodium
orthophosphate; Tribasic sodium phosphate;
Trisodium orthophosphate; TSP*; Phosphate of soda*.
3. Potential Hazards: CORROSIVE TO SKIN.
4. Available from chemical supply house, grocery store
or supermarket, hardware store or paint store.
5. Substitute products include Klean-Strip 0408 TSP Trisodium Phosphate Substitute No-Rinse (Prosoco, Inc.) and water-based solutions containing baking soda or borax.
H. Soft cloths
I. Steel wool
J. Plastic sheeting and duct tape to cover the stripper
during dwell time.
A. 000 steel wool or synthetic pads
B. Scrapers and small picks to remove sludge
C. Steel or brass wire brushes
D. Fiber bristle brushes (1/2 to 3/4 inches long)
E. Metal containers such as old coffee cans in which to
dispose of sludge
A. Before work is begun on removing the existing paint film
or otherwise preparing the surface all sources of excess
moisture shall be inspected and repaired or replaced as
1. Comply with recommendations of manufacturers of
chemical cleaners for protecting building surfaces
from exposure to their products.
2. Protect glass, unpainted metal trim and polished
stone from contact with acidic chemical cleaners by
covering them with liquid strippable masking agent
or polyethylene film and waterproof masking tape.
Apply masking agent to comply with manufacturer's
recommendations. Do not apply liquid masking agent
to painted or porous surfaces.
3. Protect unpainted metal from contact with alkali
chemical cleaners by covering them either with
liquid strippable masking agent or polyethylene
film and waterproof masking tape.
4. Protect adjacent surfaces, including grass, shrubs
and trees with paper, drop cloths and other means.
Items not to be painted which are in contact with
or adjacent to painted surfaces shall be removed or
protected prior to surface preparation and painting
5. All waste material shall be collected at the end of
each work day and properly disposed of. It is
considered Hazardous Waste.
6. Work area shall be sealed to prevent the spread of
dust and debris beyond the work site.
7. If vacuums are used to clean area, machines shall
be equipped with HEPA (High Efficiency Particulate
Air) filters to insure all lead dust has been
contained and removed.
3.03 ERECTION, INSTALLATION, APPLICATION
A. Rust Removal:
1. Brush apply commercially available chemical rust
removers such as "Naval Jelly" (phosphoric acid),
and allow to dwell according to manufacturer's
CAUTION: STAY AWAY FROM HYDROCHLORIC ACID BASED
PRODUCTS AS THEY MAY LEAD TO FUTURE CORROSION.
2. Wipe off residue with mineral spirits and either
steel wool or soft rags.
3. Dry immediately with clean soft cloths or using an
industrial blow dryer. Follow direction of grain
in metal. DO NOT TOUCH CLEANED ORNAMENTAL METAL
4. Prime immediately to prevent rust.
B. Clean small pieces which can be removed.
NOTE: REMOVE ONLY AS MUCH PAINT AND RUST EACH DAY AS CAN
BE PRIMED THAT SAME DAY. BARE IRON AND STEEL WILL BEGIN
TO RUST AGAIN WITHIN A MATTER OF HOURS. IT SHOULD NOT BE
ALLOWED TO SIT UNPROTECTED OVERNIGHT.
1. Soak in a solution of hot water and TSP, TSP-Subsitute, or sudsy
ammonia to loosen the paint.
2. Remove paint with scrapers and/or a wire brush.
3. A final wipe down with mineral spirits may be
necessary to help remove final traces of paint.
4. Dry immediately and prime to prevent rusting. A
heat gun, set at the lowest temperature, can be
used to hasten the drying time. DO NOT USE HIGH
HEAT AS THIS MAY DISTORT THE METAL MEMBERS.
C. Remove any loose paint not already removed with the rust
using a chemical paint remover.
NOTE: IF THE PAINT IS ADHERING SOUNDLY LEAVE IT ALONE-IT
PROVIDES EXTRA PROTECTION. FEATHER THE EDGES OF THESE
AREAS TO PROVIDE A SMOOTH FINISH AND APPEARANCE.
1. Brush the chemical onto the surface in the amount
recommended by the manufacturer. Thicken if
necessary with cornstarch or fumed silica.
2. Cover with plastic and allow to sit or "dwell"
according to the manufacturer's instructions.
3. Remove sludge using scrappers and steel wool. A
second application may be required on those areas
where paint is especially thick or the detail is
4. After removal has been completed using chemicals
rub all surfaces down with mineral spirits to
remove all traces of chemical and waxy residue.
a. To test whether all chemicals have been
removed and a neutral pH achieved, dissolve a
2" piece of phenolphthalein in denatured
b. Brush the solution onto the surface. If it
turns a shade from pink to magenta there is
still chemical residue.
c. Treat the surface with additional mineral
spirits and continue testing until there is no
color change in the phenolphthalein solution.
5. Dry thoroughly and prime immediately to prevent
D. Paint all surfaces. For guidance see 05010-13-S "Primers
and Paints for Wrought Iron, Cast Iron and Steel",
05010-18-R "Applying a Sacrificial Coating to Wrought
Iron, Cast Iron and Steel", and 09900-07-S "General
Guidelines for Painting Exterior and Interior Surfaces".
END OF SECTION