Treating rusty render beads

[bits&bobs]

Hi. I am painting a rendered wall and the render beads are rusty but still stable. What would be the best solution to sort these before applying masonry paint other than replacing them with plastic beads. Thanks for your time

[davyp1]

While you could wire brush the rusty areas and then paint with 'Gavlvafroid' paint, it is my feeling that it would be better to replace the beads with either Plastic or Stainless.

[Alpinist]

How would you remove the beads without wrecking the render?

[davyp1]

Small Grinder & Diamond blade. Cut down each side of the corner about 15cm in
and carefully break out the corner rnder with hammer & bolster.

[ian gibson]

On several jobs I've tried Kurust, Aquasteel, Zinsser bin and oil undercoat on rusty beads after cleaning them off, in all instances the rust stains reappeared after 12 to 18 months.

[OchAye]

Zinsser BIN is of no use in this instance. No good for exterior use (but for knots on wood).

[ian gibson]

I know, after seeing rust converters fail over time, and oil undercoat, I thought why not give it a go on another job, lasted about a year before the rust stains came through again. In the words of Neil Young, "rust never sleeps".

[Desmondo15]

Has anyone tried coverstain?
I always thought hammerite would do the job then painted over.

[ian gibson]

I think the problem is that the render covers most of the bead so whatever you put on it, it's not really getting at the underlying rusting steel. I know builders who still use galv beads on externals instead of stainless or plastic just because they are cheaper, drives me round the twist.

[bits&bobs]

I think the problem is that the render covers most of the bead so whatever you put on it, it's not really getting at the underlying rusting steel. I know builders who still use galv beads on externals instead of stainless or plastic just because they are cheaper, drives me round the twist.

Yes think that is bang on. Gonna go with plastic beads which will definitely do the trick

[bits&bobs]

Thanks everyone for your input

[davyp1]

Thanks everyone for your input

In my first post to your thread, I did suggest Galvafroid as a solution but also confirmed that I personally would replace the beads with Plastic or Stainless.
I just thought it prudent to let you know that it is my feeling with the correct preparation that you could get four years or more, by treating just the rust areas with Galvafroid I will outline the necessary prep as follows:-

• Using an 1/2" Cold Chisel, remove the render from the rusty areas (obviously you can only expose the external face of the bead)
  Wire brush all rust areas
  Rub down all rusty metal exposed with fine sand-paper or emery cloth.
  Apply Galvafroyd as per instructions on the tin (my feeling is two coats)
  After 48 hours apply 2 coats of Unibond (PVA) Diluted as stated on the can, 2nd coat just before render repair.
  With the render repairs being all small and quite tight, I would suggest you use silver sand mixed at 4:1 by volume (you can buy bags of this that Pavoirs use dry).
  If your existing render is a smooth finish, you should be able to blend it in using a sponge.

Replacing all the beads is a mamoth task, the above would give you a stay of execution if you need it!

Cheers

https://www.google.co.uk/webhp?sourceid ... galvafroid