Staining on lime pointing

[Socksitis]

Hi,
thoughts please on the staining on some dubbing out I have done on a chimney breast. I think the internal section of the chimney breast is pretty poor. In due course it will be lined, but in the mean time I am replastering the wall, this is the upstairs section, I would not be surprised if there hadn't been problems with this chimney in the history of the house (very old).

DO you think the staining will carry on through the two or three coats of lime plaster? Has anyone had any experience of parging. I have plenty of cow dung, but am not sure of the method?
Picture too large to post, will work on it

 

[88v8]

If soot deposits have made their way through the brick/stonework, they will certainly come through the lime plaster.
We had this problem on an upstairs breast in our previous (1920) house. I covered it in Foildamp stuck onto the plaster with Foildamp adhesive, and that was OK for 25+ years, then the staining started to appear around the edges, so I painted over it with stain blocker and fortunately had some spare 25yo wallpaper with which to cover it. Then we sold the house.**

Parging... if you can get in there... with thanks to the Downsizer forum

'Get a bucket of fresh cow dung - scraped off the floor of your nearest milking parlous is the easiest way.
Add some water and whisk to make a slurry the consistency of melted ice-cream.
Apply a couple of coats of the slurry with a brush, with the surface allowed to dry between each coat, and then a coat of parging mix made from a 1:2 lime/sharp sand mix, with dung added instead of water to make a sloppy mix.
Plaster on top of that and you won't get stains leeching through.
Exactly why cow dung is so effective for parging chimneys would be a good subject for a dissertation. We know it works, but not how it works - is it down to the cellular material that has passed through the cow's stomachs, or is it the mucus and other fluids that the cow has added to the mixture, as it were? As far as I know, no-one has yet studied this (perhaps understandably - two years immersed in cow crap isn't most academics' idea of a good time).

https://forum.downsizer.net/archive/lime-and-tar__o_t__t_46536.html

**the cause in our case was a gascoal fire in the dining room, which we used during dinner most winter evenings. The chimney was not llned.
Gascoals tend to burn quite cold, especially if ticked over as ours was. This deposits condensation in the cold - upper - parts of the flue, and the consequent damp leaches tar deposits through decayed parging and pointing. Lining would as you say, be a final solution.

Meanwhile, let us know how you get on with the cowdung. I believe there is a science to its precise composition called Dungshui.

Ivor

 

[Socksitis]

Thank you ivor, Better get my fresh co w dung on the wall. Probably best this time of year before the blowflies and dung flies are active!

 

[Bevmarley]

We have had the same problem on a lime washed wall. It has come through yellow. We are intending to paint another wall which may have the same problem but we have used keim staincover which we hope will help. We will let you know the outcome.

 

[livias]

Stainblock should work fine in my experience. Then paint or plaster over

 

[Bevmarley]

Keim I.G. is the one we are trying.

 

[Socksitis]

Is cow dung so bad that no one is using this free product? I will try it and we will see how good it is compared to the purchased products

 

[livias]

Cow dung is used on the inside of the chimney. Once the staining is into the bricks then you have missed your chance