Thread: Stubborn rust stain

Annoyingly on the corner of my pond in full view is a rust stain that keeps appearing, on this corner there is a metal corner bar which the render runs upto, the rust is from this, i have rubbed it down and used a stain block but it keeps coming through after a while, any idea's anyone on how i can stop this from happening? in a months time or so i will be re painting the render again so it would be a good opportunity to rectify this issue then.... if there is a remedy !
thanks guys Steve....

Originally Posted by smartin

Annoyingly on the corner of my pond in full view is a rust stain that keeps appearing, on this corner there is a metal corner bar which the render runs upto, the rust is from this, i have rubbed it down and used a stain block but it keeps coming through after a while, any idea's anyone on how i can stop this from happening? in a months time or so i will be re painting the render again so it would be a good opportunity to rectify this issue then.... if there is a remedy !
thanks guys Steve....

everytime i've seen rendering done on site it was with plastic edge trims or stainless steel.
as most metals even cheaper 304 ordinary stainless steel doesn't like the high alkalinity you get with cementious render.
so they use austenitic high nickle stainless steel or plastic beads

are the corner beads galvanised steel?
galvanised steel hasn't been used for render for years now, against nhbc building regs as causes rust run off.

you could try sealing with a rust converter primer before painting

Originally Posted by davethefish1

everytime i've seen rendering done on site it was with plastic edge trims or stainless steel.
as most metals even cheaper 304 ordinary stainless steel doesn't like the high alkalinity you get with cementious render.
so they use austenitic high nickle stainless steel or plastic beads

are the corner beads galvanised steel?
galvanised steel hasn't been used for render for years now, against nhbc building regs as causes rust run off.

you could try sealing with a rust converter primer before painting

Hi Dave,
in all honesty i don't know what it is, it would not surprise me at all if it was Galvernised, i will try what you have suggested, many thanks