[Rob_Mac]

Darren

Wanted to take this out of the 'What have you cleaned' topic because it is something that could be added to moving forward and that could be a useful one stop for all surface problems. What the problems to each surface could be, how they can be recognised and what the cleaning methodology could/would be to resolve the problem/s

I normally keep about 12 - 15 tabs open, for flicking between various websites but I closed them down last night. I think I searched for staining to sandstone, atmospheric problems on sandstone, the effects of weathering on sandstone etc. Very much current information and you would suspect that a lot of it would be down to acid rain but it's a bit wider than that.

Mention of pollutants from agriculture, vehicle emissions and the way that our complete lifestyle adds other factors into the atmosphere.

Here's one I looked at -

http://www.buildingconservation.com/articles/atmospheric/atmospheric.htm

It's easy to blame acid rain for everything but my guess on that sill would be erosion of the surface due to any and all of the above, rain, possible staining from the exposed window frames, the sill staying damp - longer than it should, algae growth into the substructure which is deeper than a 'light ' pressure wash can handle.

I understand completely why you wouldn't want to go heavy on the pressure washer and cause further problems.

http://www2.rgu.ac.uk/schools/mcrg/misst.htm - this is going on about the sandstone in Scotland and though a little dated shows some problems and methods used on their major buildings.

Rob

[chris scott]

It's Carbonation of the sandstone sill.

[Rob_Mac]

You can't say that off the photo!

You changed your reply on the post and then omitted the rain comment you made. So were you wrong in the 1st instance?

Rob

[Rob_Mac]

I ain't even going to get into a debate with you.

Rob

[chris scott]

You can't say that off the photo!

You changed your reply on the post and then omitted the rain comment you made. So were you wrong in the 1st instance?

Rob

Carbonation of the sandstone is the result ...the cause is what I have not reiterated.

The large glass window and rain is the cause...pay attention will you I am trying to educate you.

[Rob_Mac]

I don't need any educating from a moron! . I've put a smiley so you don't get anymore of a inferiority complex

Rob

[chris scott]

I don't need any educating from a moron! . I've put a smiley so you don't get anymore of a inferiority complex

Rob

[Roger Oakley]

But is it Sandstone or a Limestone?, lots of "local" Limestones would have been used at the time of the building of that building. But I feel that my answer in the original thread, that it is staining from the metal window frames is the answer, and staining from many years is what the cause is.

Identify the stone then Identify the cause then you can move forward with this.

Don't want to get into a big debate about this as there are enough comedy threads going around at the moment.

[chris scott]

Roger...Smudger also mention that the sill is "soft" ..this is classic carbonation along with the staining.

The rain hits the impermeable window ...rolls down the glass, the area directly below becomes saturated. (check out the first picture..below the  window and sill).

The carbon dioxide in the water  turns into carbonic acid when mixed with the calcium in the stone.
This then "rots " the stone. This can then accelerates freeze/thaw cycles . Whereas the stone becomes even more permeable accepting more water... then along comes the frost. The water in the saturated stone  expands and blows the stone.

It,s advanced weathering "stones" have been doing it for years.
Rob........... not the Rolling "stones" as in gimme shelter.

[Rob_Mac]

Ok

Rob