Tea staining is a brown surface discolouration caused by chlorides and free iron on the surface, not a failure of the steel. Pitting is different and worse: localised corrosion that eats into the metal. Neither is rust in the sense a cast iron pan rusts. The distinction decides whether you clean it or replace it.
What Causes the Brown Staining?
Chlorides in the environment, salt air being the common one near the coast, combined with free iron contamination on the surface from fabrication or from a cleaning product. The chromium oxide layer that protects stainless has been compromised at the surface, so a discolouration forms that looks like rust and is not.
How Is That Different From Pitting?
Pitting is corrosion that penetrates. It starts as a small dark spot, develops a cavity, and can perforate a thin section. Tea staining sits on the surface and can be removed. A pit cannot be cleaned away, only dressed or the section replaced.
Tea staining
- Brown discolouration on the surface
- Removable with the right treatment
- Cosmetic, not structural
- Treated as rust, it gets worse
Pitting
- Localised cavity into the metal
- Cannot be cleaned away
- Can perforate a thin section
- Cause needs finding, not just treating
The practical test: if it comes off with the right treatment, it was staining. If there is a cavity under it, it was pitting and the cause needs finding.
Is It the Same as Rust?
Not in the way people mean. Our how to remove rust from stainless steel guide deals with the cases where the surface genuinely has iron contamination or rust bleeding from a neighbouring component. Tea staining is the chloride version, and treating it as rust leads to abrasive cleaning that makes it worse.
Why Does 316 Solve Most of It?
Because molybdenum in the alloy raises resistance to chloride attack. Near the coast, on a venue with salt air, 316 is the specification and 304 is the compromise. Our 304 vs 316 grade comparison covers the exposure thresholds, and the food grade stainless steel guide covers what else the grade affects.
316 is not a marketing upgrade. It is a specification for a specific exposure, and the coast is that exposure.
What Does Correct Cleaning Involve?
Along the grain, with a non-chlorinated product, and no steel wool. Abrasive pads that have touched carbon steel introduce free iron and cause the very staining being removed. Passivation restores the oxide layer once the surface is clean.
The routine for a coastal venue is in our stainless steel maintenance guide, and the finish that makes cleaning easier is covered in the stainless steel finishes guide.
Where this matters most in our area
Coastal and near-coastal venues across the Sunshine Coast and Gold Coast, both core delivery areas for us. The relevant local pages are Sunshine Coast stainless steel benchtops and Sunshine Coast exhaust canopies. Outdoor kitchens are the worst case, covered in the outdoor BBQ kitchen and alfresco planning guide.
Frequently Asked Questions
Is tea staining harmful?
It is cosmetic and removable. Pitting underneath it is not.
Can I clean it off myself?
Usually, with the right product and direction. Abrasives make it worse.
Does it mean the steel is faulty?
No. It means the surface has been exposed to chlorides or contaminated with free iron.
Will 316 stop it completely?
It substantially reduces the risk. No stainless is immune in a salt-air environment.
Does it come back?
Yes, if the environment is unchanged and the routine is not maintained.
Should I replace the bench?
Only if there is pitting that has thinned the section. Staining alone is not a reason.
Book a Site Measure
If a coastal kitchen is showing staining, the grade, the finish and the cleaning routine are usually all contributing. We fabricate in 316 at our Burpengary East workshop and install across the Sunshine Coast and Gold Coast. Call 07 3888 7534.
Coastal Kitchen Showing Staining?
We will tell you whether it is tea staining or pitting, and what the grade should have been.