Other Methods
There have been many methods used over the years to try and prevent corrosion. These methods include dehumidification, evacuation of air/gases, nitrogen purges and protective barrier coatings. Each method has it’s pros and cons.
Oils
Pros:
- If fully coated, oil does a decent job of repelling water on the surface of the metal, thereby preventing rust.
Cons:
- Given time, moisture will diffuse through oil, make contact with the metal surface and cause corrosion or rust.
- Oils are messy and sticky to apply.
- Oils must be removed and the surface cleaned with a solvent or other method.
- Oils are hazardous and disposal may be a problem.
- Oils introduce health risks to workers.
- Oils attract dust and dirt which are not only messy but can lead to corrosion through contamination.
RP Liquids
Pros:
- If fully coated, a good RP liquid can do a decent job of repelling water on the surface of the metal, thereby preventing rust.
Cons:
- Given time, moisture will diffuse through RP liquids and make contact with the metal surface and cause corrosion or rust.
- RPs can be messy and sticky to apply.
- Most RPs must be removed and the surface cleaned with a solvent or other method.
- Many RPs are hazardous and disposal may be a problem.
- Many RPs can introduce health risks to workers.
- Many RPs attract dust and dirt which are not only messy but can lead to corrosion through contamination.
- If you are mixing the RP, ratios and proper mixing methods are important and mistakes can lead to rust issues if not caught.
Paints
Pros:
- If a product is able to be painted, this should provide the best method of corrosion prevention.
- A paint is visible on the surface providing assurance that a metal parts has been coated.
Cons:
- It is typically not practical or feasible to paint a metal part that is used in engines, transmissions, electronics, or other critical applications.
- Paints are messy to apply.
- Paints are permanent and not likely to be removed.
- Paints can introduce health risks to workers.
Desiccants
Pros:
- Alters the environment to remove moisture and humidity.
- Can work well when applied with a good vapor corrosion inhibitor.
Cons:
- Adsorbs moisture in the air but doesn’t address the surface of the metal.
- Once desiccant pack reaches maximum adsorption it ceases to work.
- Does little to affect other corrosive effects such as gases, contaminants or acidic materials in packaging.
- In large packaging scenarios, it is not practical to rely solely on desiccants to desiccate an area; must be used in combination with other materials.
Vapor Corrosion Inhibitors
Pros:
- Clean, safe, easy to use.
- Combines packaging materials with corrosion inhibitor.
- No messy liquids; leaves returnable packaging and shop environment clean.
- Good VCIs contain no hazardous chemicals to humans or environment.
- Good VCIs have a lasting effect for long term storage yet work quickly to saturate airspace.
- Volatilization of chemical allows VCIs to replenish themselves.
- Ideal for shipping and both short and long term storage.
- Can be used in-process in a production setting.
- Safe on other materials such as plastics, rubber and vinyl.
- Not permanent; allows for flexibility.
Cons:
- May require to be used in combination with other corrosion inhibitors for outside storage.
- Not permanent like a paint.
- Abundance of water infiltration can wash out VCI.
- If rust is already present, may not work as well as an oil in masking a problem.
