Painting over render with rust bleed from metal beading

[Roscoepeko99]

Hi all,

Newbie just bought an old victorian house with quite a bit to do. Wonder if anyone could help.

The lower part of the house has been rendered and there is rust bleed showing through from what seem to be galvanized beading used for the render. It is not excessive but want to do the job properly and not have it show through again. On one area the beading is visable and the paint has blistered.

A quick search on this forum and i found a similar post dated back to 2004 where a product Comma Stop rust was recomended, but I cannot find it listed anywhere when googling it ? Is the product still available and can it be overpainted with masonary paint - any other suggestions would be greatly appreciated - ill take some pics and upload tomor.

Cheers
Ross

 

[LJW61]

Rust stains will always bleed through water-based paints so you need to overpaint the rust spots with an oil-based primer or undercoat(or Zinsser BIN if youre flush!) then (when dry)overpaint with your exterior emulsion ,I use Dulux Weathershield or Crown Stronghold .
Ive just re-painted a house I first coated with Weathershield (trade) 7 years ago - and apart from staining from road 'soot' it was in remarkably good condition!

 

[Robbie uk]

Thing is with rust is that unless it is treated with a rust preventer it will still come through the oil based paint. The product you mention is available at most car accessory shops. Kurust is another good one.

 

[LJW61]

True Robbie, rust should be treated at the source ie. the metal,if it can be reached , but if its too deep under the render to get to then all you can do is treat the staining, Ive found that oil-based is sufficient there..
btw. Rust needs oxygen as well as water to thrive, starve it of either then it cannot spread
for peace of mind then Comma is a good cheap rust stabilizer we use on motorcycle frames with great results

 

[Roscoepeko99]

Thing is with rust is that unless it is treated with a rust preventer it will still come through the oil based paint. The product you mention is available at most car accessory shops. Kurust is another good one.

Thanks for the replies - So a rust treatment from a motor factor followed by normal household oil based undercoat and / or satin then exterior emulsion over the top ? there is only small area where the bead can be seen - should i expose the bead in other places in order to treat it and prevent it becoming rust or maybe just do the edges (where not rusty) with undercoat and / or satin in the anticipation that if i only treat affected areas the others will be following suit very shortly. ? Ive uploaded a couple of pics.

Thinking about it the idea of exposing beading seems a tad over the top now - but maybe paint with oil based 1st ??

//www.diynot.com/network/Roscoepeko99/albums/

 

[LJW61]

If the metal is showing (especially if loose/flaky 'live' rust ) then treat it with Comma or similar , if its not then best to leave it under its render.. re-rendering is going to introduce more water which will 'creep' under/into the surrounding area (& metal) beneath the the surface..

Ive just completed a cottage exterior for a customer that I have painted 5 times over the last twenty years, the first time I did so a pair of wall ties that were rendered over were rust-staining the paint, I sprayed the affected area with Duplicolour white primer aerosol before two coats of Dulux Weathershield ...They've never shown through since..

 

[Robbie uk]

You can use Comma, Kurust, or Jenolite, all very good at stopping rust.