Care & Maintenance
CARE & MAINTENANCE
You’ve made ‘the lasting decision’ and now for ‘the lasting look’. Cleaning with soap or a mild detergent or even an industrial cleaner is not a realistic approach with the fine meshes- as you cannot reach between all the weaves and the tea staining will continue to occur. Pickling & passivation and electro polishing- is the solution! Please note as with anything internal or external cleaning and maintenance is still required to keep your mesh clean and preserve its appearance.
Pickling & passivation and electro polishing- is a simple and inexpensive process that will last and stand the test of time.
What is tea staining?
Tea staining is the brown discolouration of the surface of stainless steel caused by corrosion. It is a cosmetic issue that does not affect the structural integrity or life of the stainless steel. Tea staining occurs most commonly within 5km of coastal areas however it can also occur in polluted urban environments.
For further information please refer to The Australian Stainless Steel Development Association (ASSDA) FAQ 6. Preventing Coastal Corrosion (Tea Staining)Â and our BLOG post ‘Why Does my Mesh have an Unsightly Brown Discolouration’.
WHY IS MAINTENANCE NECESSARY?
Surface contamination in the form of deposits must be prevented. These deposits may be minute particles of iron or rust from other sources such as tools previously used on carbon steel. There are also naturally occurring atmospheric conditions which produce deposits, such as salt from marine environments. The more aggressive the environment is the more regular the cleaning program will be required.
The cleaning frequency of stainless steel depends on four points;
- The environment
- Position of the stainless steel structure
- Stainless steel surface finish and structure design
- Client’s expectations
A rule of thumb for cleaning external stainless steel is when you clean the surrounding windows also clean the stainless steel.
Industrial Cleaning Product
Industrial cleaning products are also available and may be considered for harsh environments. Please source from a reputable surface finisher and follow manufactures instructions.
A guide to specifying and cleaning external stainless steel
| Environment | Grade 304 | Grade 316 |
|---|---|---|
| Clean Inland | 3 – 6 months | 6 -12 months |
| Polluted urban/Industrial | Not suitable | 6 -12 months |
| Coastal/Marine (not splashed) | Not suitable | 3 – 6 months |
Source: ASSDA
Note: Rainwater is an effective natural cleaner, stainless steel that does not get rained upon will need more frequent cleaning.
We have discussed Tea Staining and unfortunately cleaning with soap or a mild detergent or even an industrial cleaner does not suffice with the fine meshes- as you cannot reach between all the weaves and the tea staining may return under particular conditions. Where this is an issue is when the mesh is being used for its aesthetic appeal in architectural applications or external applications.
The solution is pickling & passivation and electro polishing- a simple and inexpensive process that will last the test of time.
Stainless steel can be contaminated by carbon steel which will lead to corrosion. Ideally, a fabricator will have dedicated workshop and tools for stainless steel only.
Contamination can be picked up from:
- Grinding wheels, wire brushes and linishing belts
- Steel storage racks
- Tooling used with other metals
- Contamination from grinding or welding sparks from nearby carbon steel fabrication
It is recommended than when stainless steel is to be used for external purposes that it be electropolished.
– Remove surface flaws & impurities
– Remove high points and round troughs
– Passivates greater than any other process
– Maximises the protection of stainless steel against tea-staining and corrosion
– Brightens the surface finish to provide a bright and shiny chrome-like appearance
– Smooths the surface enabling the surface to naturally wash, thereby significantly diminishing the likelihood of future rust
Both types of metal finishing have great advantages for stainless steel wire & mesh
Pickling & Passivating when applied to the surface of stainless steel
– Removes contaminants
– Removes heat tint due to welding
– Formation of a continuous enriched chromium oxide protective layer
Both pickling and passivation solutions can employ dangerous acids that can damage both the operator and the environment if not handled correctly. Stainless pickling acids are highly corrosive to carbon steel.
It is essential that all acids are thoroughly removed by rinsing the component after completing the process. Residual hydrofluoric acid will initiate pitting corrosion.
For further information please refer to:
The Australian Stainless Steel Development Association (ASSDA) www.assda.asn.au
Visit ASSDA’s technical FAQ’sÂ
