Why a Stainless Screw Can Corrode the Aluminium Around It

The strongest-looking screw is not automatically the right screw

Coastal corrosion can occur at the contact between dissimilar metals. In the presence of moisture and salt, one metal can become the part that corrodes more quickly while the other appears unchanged.

This is why a stainless screw can remain bright while the aluminium around it shows local damage.

Bathrooms contain more mixed metals than they appear to

Frames, brackets, drains, towel rails, hinges, mirror fittings, cabinet hardware and concealed fixings may combine different metals and coatings. The risk depends on the materials, area relationship, moisture, salt and whether the parts are electrically isolated.

The visible product finish does not necessarily reveal the hidden fastener or bracket material.

Specify the assembly, not only the front

For coastal work, confirm the manufacturer’s fixing instructions and compatible hardware. Avoid substituting a random screw or bracket because it is available on site. Keep the product documentation with the handover so future replacement parts do not introduce a new material conflict.

This is a detail worth resolving before the finished tile, mirror or aluminium frame makes access difficult.

Read why stainless steel can still rust in Umhlanga, or see why bathroom fittings need a proper handover parts list.