Lime resources

[NickB_99]

Hello all

After reading a lot of recent posts regarding lime plaster/render etc, I thought it was about time I did some reading up on the subject.

I've found a few links etc, but am probably getting a bit more confused than anything else with all the different types/terms.

Coming from gypsum experience, I'm keen to see how the process differs and materials behave. e.g. is fine lime plaster finished by polishing with some water, like gypsum multi-finish is?
Not been able to find anything on this.

Are there any idiots guides to lime plastering or decent resources that I can be pointed at?

Thanks in advance.

 

[dougalhouse]

I'm with you. Need to do a course in lime work me thinks.

What I'd like to know is; does it really cause serious problems if you patch up an old wall that is lime / sand cement with gypsum plaster and then skim over whole wall with gypsum multi finish? Cos I have to admit I've done this several times but am becoming worried that I've done something wrong!

 

[peaps]

I'm with you. Need to do a course in lime work me thinks.

What I'd like to know is; does it really cause serious problems if you patch up an old wall that is lime / sand cement with gypsum plaster and then skim over whole wall with gypsum multi finish? Cos I have to admit I've done this several times but am becoming worried that I've done something wrong!

Yes it does cause problems, damp.

 

[dougalhouse]

Excuse my ignorance but I can understand damp affecting an external solid wall if gypsum used but not internal or cavity walls?

 

[peaps]

Excuse my ignorance but I can understand damp affecting an external solid wall if gypsum used but not internal or cavity walls?

Well you didn't mention cavity walls... But it all depends on the construction. Many victorian houses have shallow or no footings and no damp proof although many do have a cavity. Damp will breach the internal wall from the floor area, rising...

Lime was used to combat damp and movement in old buildings. Many factors come into play when renovating old property including te area, method, type of bricks and stone used.

SO the idea is to replace with what has come off, if it has lime on the wall it's there for a very good reason.

 

[Possel]

Coming from gypsum experience, I'm keen to see how the process differs and materials behave. e.g. is fine lime plaster finished by polishing with some water, like gypsum multi-finish is?

No, you don't use water - I think that would completely wreck the finish (perhaps peaps would advise); each coat is trowelled smooth and then re-trowelled later when it has started to go off. I understand that this brings the lime putty to the surface which gives a very smooth finish. Using a high quality lime plaster (e.g. lime putty with marble dust as well as fine sand) as the final skim, a very fine finish is possible; it just depends how much skill, money and time you are willing to throw at it!

I'm with you. Need to do a course in lime work me thinks.

Various companies e.g. Mike Wye in Devon do one day courses aimed at educating owners/DIY-ers as well as professionals about lime mortar/plaster. If you buy stuff from them, they are also very willing to give lots of free advice!

 

[NickB_99]

Thanks possel, a great answer

 

[peaps]

Coming from gypsum experience, I'm keen to see how the process differs and materials behave. e.g. is fine lime plaster finished by polishing with some water, like gypsum multi-finish is?

No, you don't use water - I think that would completely wreck the finish (perhaps peaps would advise); each coat is trowelled smooth and then re-trowelled later when it has started to go off. I understand that this brings the lime putty to the surface which gives a very smooth finish. Using a high quality lime plaster (e.g. lime putty with marble dust as well as fine sand) as the final skim, a very fine finish is possible; it just depends how much skill, money and time you are willing to throw at it!

I'm with you. Need to do a course in lime work me thinks.

Various companies e.g. Mike Wye in Devon do one day courses aimed at educating owners/DIY-ers as well as professionals about lime mortar/plaster. If you buy stuff from them, they are also very willing to give lots of free advice!

As you say it's not usual practise to wet when polishing lime finish in the way you do with gypsum.

Venetian plaster is a good example of the quality finishes you can get from lime and marble dust.

If done correctly a lime finished wall from start is a long drawn out process. I don't subscribe to the school who work lime scratch and flaot coats while green. I wait for them to go off before working them, takes time. This allow for a better job all round and in many cases saves time. Green walls are prone to shrinkage and you can guess what is going to happen in this case where different setting times are working against each other. Shrinkage and cracks, this is when you will see lime walls wet finished, to put a bad job "good" again. Adds to the work load as well.

Same goes for the water you add to mixes. You need to get this right because it adds to shrinkage. Get the mixes right and let them cure right and you will have a great finish that will last a life time.

This is the difference between a plasterer and a spread. Modern plasterers who don't know traditional methods are good in their own right but not plasterers in the traditional way of thinking.

I can't tell you the amount of time I have etered a period property to find modern gypsum plasters used and created a nightmare with plasterers have come back time after time not knowing why.

Many large public building laden in "marble" is in fact lime plaster made to look and feel like marble.