moon Posted July 15, 2004 Share Posted July 15, 2004 No not washing powder or the other stuff.........Our outhouse/workshop has what appears to be a flat roof of concrete overlaid with corrugated sheets to run off the rainwater. This year we have a white powdery secretion on the inside of the roof in one patch which is then covering everything underneath in a snowy powder. I suspect it is water penetration producing a salt deposit. Any ideas about what it is and how best to tackle it.Bob (36) Dept not age.....lol Link to comment Share on other sites More sharing options...
Carly Posted July 15, 2004 Share Posted July 15, 2004 Sounds like saltpeter (potassium nitrate, I think? But someone will no doubt correct me). Fairly harmless and common in older houses (especially damp outhouses), but I think that you can by solutions from DIY stores to dissolve/suppress it... otherwise you can mix it with charcoal and make gunpowder out of it, perform voodoo rituals with it, or use it as a fertiliser or as a food preservative. They also used to put it in army rations because it, erm, suppresses male virility! What was I saying about it being harmless...?Carly (absolutely full of useless facts) Link to comment Share on other sites More sharing options...
Rtony Posted July 19, 2004 Share Posted July 19, 2004 Try looking up effluorescence.tony Link to comment Share on other sites More sharing options...
Caterham7 Posted July 30, 2004 Share Posted July 30, 2004 The Cement and Concrete Association produce a publication 'Efflorescence on Concrete'which explains the three most common types of efflorescence,their causes and remedial measures.Your's will probably be lime blooming or salt crystallisation.Either way you should stop water penetrating the concrete.If you need more details from this publication PM me.Regards Tony CEng MIStructE Link to comment Share on other sites More sharing options...
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