Exterior Finishes

This stainless steel “passivation”treatment reduces rust and corrosion and makes it look like new.

Nothing is sadder for a homeowner than to see expensive and gorgeous materials that have been left to corrode in the elements.  Stainless steel finishes are a good example. Most homeowners don’t know the basics of caring for these nice finishes and if you happen to live in a corrosive environment or close to the ocean, it really really can take a toll.

Here is a process we use at HPS Palo Alto, Inc. to clean, polish and passivate exterior stainless steel architectural finishes. This is a time and labor extensive process but is quite effective at returning weathered stainless back to original glory. This treatment should also be a mandatory specification for new stainless steel products and installations. Let your designer or architect know.

Stainless steel passivation
Before with heavy corrosion
Stainless steel passivation and polishing
After treatment

Material needed:

Stainless steel passivation
Stainless steel gate after treatment
  • Scotch Brite pads
  • Wichinox paste
  • Phosphoric acid (available in bulk from some commercial nursery suppliers)
  • Baking soda
  • Distilled water
  • Denatured alcohol
  • Molecular surface sealer (Everbrite Protectaclear)
  • Dust free absorbent cloth for drying and application of alcohol.



Do not use this process on stainless steel sheet material with a factory machined finish. Always test first on an area that is least exposed to be sure that it meets with your aesthetic needs.

The stainless steel passivation process

Step 1

First wash and scrub the metal with regular tap water and a Scotch Brite pad. This will remove dirt, dust, bird droppings and any accumulated surface residue.

Step 2

Next vigorously scrub the entire surfaces with fresh pads along with a mix of 2 parts phosphoric acid and 10 parts distilled water. Scrub the length of the metal parts and go with the “grain” not across it.  Continue to scrub and polish the metal until all rust and corrosion has been satisfactorily removed. Do this in small sections at a time in order to not miss any spots. Heavily corroded and hard to access areas may need to be done several times.

Step 3

During the first step, apply Wichinox paste to any welds in the work area while the acid mix is still wet on the metal. The welds are the worst areas and the paste help to give the phosphoric acid longer to work its magic. Rinse off the acid mix from the rest of the work but leave the weld areas with paste for at least 15 minutes before rinsing.

Step 4

Mix baking soda and distilled water together in a ratio of about a box of soda to 5 gallons of water. Carefully wash all surfaces of the metal with the baking soda/water mix. This will completely neutralize any of the acid that may be left from the previous step. Scrub the welds if necessary with this mix using a clean toothbrush to remove all the paste. Rinse with a fresh batch of distilled water when done and allow to air dry.

Step 5

Wipe all metal surfaces with denatured alcohol and let dry. This removes all residue from prior steps including fingerprints, dust, oils, grease etc. and leaves the surface clean and ready for the sealer.

Step 6

When the surface is completely dry from the above step, and the appearance of the metal surface is completely satisfactory, then apply two coats of Everbrite Protectaclear sealer waiting 1 hour between coats.


The sealer is a wafer thin molecular protectant and it is completely invisible. It will last in harsh conditions and direct sun for about 2 years and keep the steel looking new and shiny. After two years the sealer will begin to break down and the steel will again be exposed and vulnerable to corrosion. The manufacturer recommends that the metal be washed again and a new coat of sealer applied every year. This way the bare steel is never again exposed to corrosion. The wash and re-coating process is much faster than the initial treatment.


If you like your expensive metal trim looking like new, this is the only reliable and lasting way to accomplish it.

Stainless steel passivation
Stainless rail after treatment
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