Going mad: plaster type for plastering bedroom

[ajbaker]

Really sorry to be asking this question again (this is my first plastering task!)... is non-hydraulic lime (lime putty and sharp sand) the correct choice for plastering a first floor bedroom?

It will be a finish coat of plaster on the original backing coat of haired lime. There are small patches of modern skim plaster that I have not been able to remove without risking breaking up the original lime behind. My intention is to lime-wash wall beforehand - to give some adhesion?

My concern is so many people have suggested hydraulic lime is the correct choice for walls. I appreciate this would cure sooner and also be much stronger. Am I not correct in thinking though the lime putty mix should become strong enough though over time?

Comments appreciated.

 

[Gervase]

Hydraulic (or fat lime) is what you want. The only reason you'd ever use hydraulic lime for plastering indoors is if the wall was permanently wet.
Use the putty with sharp sand mixed 1:3 putty to sand, and mix well before you even think of adding water, as plaster gets sloppier as it's mixed, and you don't want to end up with porridge!
Using limewash as a 'tack coat' is an excellent idea, and will help cut the suction on the old lime plaster and improve adhesion on the modern stuff.

 

[MDE]

Hydraulic (or fat lime) is what you want.

Whoops, missed out the important "Non-" before the hydraulic.
I've used DG27 from Mike Wye to cover bits of gypsum plaster when skimming a predominantly lime plastered wall, with some success. I use 3:1 for the base coat, but more lime (2:1 or 3:2) for the finish coat, and silver sand, rather than sharp sand. I suppose it depends what sort of finish you want.

 

[ajbaker]

Thank you both for prompt and concise answers. I thought I knew the answer, but getting confirmation makes me feel so much better. I recently went on the Mike Wye Practical Lime Course, but of course everything is different (messy, old and flakey!) when it comes to actually doing the work on your own. I was thinking of purchasing some DG27 for the modern stuff so again, confirmation is good.

Thanks a million.

Andrew

 

[NT]

I'm curious where use of hydraulic lime has been reocmmended, as this would not normally be used for interior plastering.

NT