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Plastering/rendering cellar walls in very old house
large patches of the original plaster have fallen off to reveal stonework underneath. In other areas normal plaster basecoat has been used which has become soft and friable due to exposure to the damp. I'm told that a traditional (non-hydraulic) lime plaster would be best for this application. In order to save money I'm considering buying 'bag-lime' from a builders merchant to make up putty (what's the minimum stand/maturing time? (builders tell me 3 days to a week, others 6 months...)). I'm also not entirely clear on what sand to use. Again the advice is mixed - some suggesting fine sharp sand and others a mix of aggregates (as this is a cellar I'm not too concerned about matching anything existing for cosmetic reasons and hoping to 'learn on the job' (realise that this would be better done by a pro but my pockets aren't that deep at the moment ;)). Any advice would be appreciated.
Personally I would just buy the lime putty, it comes in 25 kg tubs costing around £20.
Answered 10th Feb 2013
if you are sure you want to try this it will takea fair amount of paitence just to achieve a lime putty, basically get yourself a large metal bath mix 2parts water to 1 part lime mix well then sive getting rid of all the lumps then store in an airtight container for three months this will achieve a lime putty,then depending on whether you want an under coat or a top coat will depend on what type of sand you use, fine soft for a top coat, sharp for an undercoat.
as lime can be rather voilatile it is recommended that you are outside when mixing and suttably attired with saftey mask,gloves,hat, boots,and overalls.
alternativelly you could try buying it from one of the main supplier ready made as this is a lot easier.
stone tech being one
Answered 4th Feb 2013