Beginners guide to Lime Plastering

J

joemarsh20

New Member
Good morning,

I have joined to try get some advice on Lime plastering in the hope of not been sold something I don't want and a job doing incorrectly, so I hope someone can help.

I have an old Victorian terrace and wish to have an internal wall plastered in Lime to match the existing Lime that is already there. There are lots of other reasons for doing this other than aesthetics etc, and we have a slight problem with damp. This has manifested itself on gypsum plaster which has been randomly used to patch up the original Lime plaster.

My concerns are that the few people I have had to quote the job have all told me different things and I would like to clarify a few points if possible on here:

1) What is the mix for "true" Lime Plaster when applied in a thickness from brick to finished surface of 10mm and 20mm, how many coats would be required to achieve both thicknesses?

2) Is the product Tarmac Limelite (and associated base coat and finishing plaster), actually a true Lime Plaster or is it a halfway house type product that wont truly have the properties of the original stuff in my house?

3) One of the walls to be plastered is original Lime Plaster which I have had to remove the bottom 800-1000mm from the floor, can new Lime plaster be applied and "patched" into this line of original plaster?

4) Another wall to be plastered is the same as above but has had a skim of gypsum applied as well as the rest of the room (which is sound), can this be "patched" into as above with new Lime plaster?

5) Are there any other products on the market I should be aware of that people would try to pass off as Lime plaster, that isn't suite correct as the original Lime in my house?

Thank you so much if you can answer any of this for me.

Joe
 
Hi Joe,
I’ll attempt your questions in order.
Firstly, there isn’t a ‘true’ lime plaster mix, historically there are lots of mixes, it’s about finding the appropriate one for the purpose.
Plaster mixes fit for use in a Victorian building are the most commonly available, the standard being three coat work, the final coat consisting usually of lime putty and fine sand mix. The two backing coats (or one if 10mm total is required) should be a much coarser sand.

Tarmac Limelite from memory has Portland cement on the ingredient list, making it a no-no in historic buildings. Have a look at the material data sheet.

Whether the plaster can be patched successfully is down to the skill of the plasterer, with a fine top coat it should be possible.

Again, with a bit of skill and a really creamy finish coat, it should be possible to work enough of s finish to get it pretty close the the pink. Failing that, we often have situations where the repair scratch coat is brought up flush to the gypsum, blue grit the gypsum and put a finish over the whole lot.

Go to a specialist supplier, ask questions, if you’ve got a local supplier, they may also recommend a plasterer, but go and see their work.
Good luck,
Martin
 
Excellent answer thank you so much.

I know you say there isn't a "true" mix, what I was referring to possibly was a general idea of a mix, that if someone possibly tried to con me into something else, I would have some knowledge of the ingredients of lime plaster. So, in essence, what should lime plaster contain generally. I assume Lime but is it hydraulic lime, sand, aggregate, etc, etc. I know from you're answer that it should not contain any type of portland cement.

I am wary as I have had 2 people quote now and have tried to pass this Tarmac Limelite stuff off as a Lime plaster and another product that I can't remember the name of. Maybe it was drycoat of something.

I have had a proper quote, which I believe is from a genuine contractor, but at the moment its way, way, way over my budget, I think because they are so far away and its only a very small job. We may have to cope with bare walls for a some while longer.

Thanks again
 
joemarsh20 said:
Excellent answer thank you so much.

I know you say there isn't a "true" mix, what I was referring to possibly was a general idea of a mix, that if someone possibly tried to con me into something else, I would have some knowledge of the ingredients of lime plaster. So, in essence, what should lime plaster contain generally. I assume Lime but is it hydraulic lime, sand, aggregate, etc, etc. I know from you're answer that it should not contain any type of portland cement.

I am wary as I have had 2 people quote now and have tried to pass this Tarmac Limelite stuff off as a Lime plaster and another product that I can't remember the name of. Maybe it was drycoat of something.

I have had a proper quote, which I believe is from a genuine contractor, but at the moment its way, way, way over my budget, I think because they are so far away and its only a very small job. We may have to cope with bare walls for a some while longer.

Thanks again
Click to expand...
We are on the same page here . I am confused Don’t know what to make out of it. Great answer btw, with a lot of info. I was told that true lime actually is hot and wet lime , used in the past before cement took over . The main difference between the true lime and the modern lime is the content of free lime , which separates lime from lime. I think I have been conned too.
 
Anglian lime company, or Mike wyh limes, will sell you corse stuff and fine coat ready mixed in buckets.
 
vfr12 said:
We are on the same page here . I am confused Don’t know what to make out of it. Great answer btw, with a lot of info. I was told that true lime actually is hot and wet lime , used in the past before cement took over . The main difference between the true lime and the modern lime is the content of free lime , which separates lime from lime. I think I have been conned too.
Click to expand...
Modern lime putty is industrially pure (very high free line content) and I think it’s safe to say that historically that wasn’t the case.
If you look at a Victorian OS map, you’ll find lime kilns everywhere, really everywhere, like four in a small town. The setting speed and cured strength, as well as how reactive to water, rely heavily on the geology. So a kiln from the nearby town might make a lime that sets hard and fast, whereas a few miles the other way gives you something softer and slower.
All of this is lost, with practically everything coming from Buxton (non-hydraulic) or Bordeaux (naturally hydraulic, NHL).
Again, it’s horses for courses, the range of performances available, even from the limited sources, from varying sand grading, lime strength and ratios is pretty vast.
Hot mixing is using quick lime (violently reactive with water) and wet sand. Not for the faint hearted and all good fun, till someone loses an eye!
 
Ritch said:
We don’t touch lime I leave that to a good pal of mine who is a expert in traditional plastering lot of that s**t round my way and big bucks in it too
Click to expand...
Ring is next time Ritch, it’s not a dark art, it’s spreading gear up the wall! We like speedskims, plaxiflex and time served plasters that haven’t done lime!
 
Martin Brown said:
Modern lime putty is industrially pure (very high free line content) and I think it’s safe to say that historically that wasn’t the case.
If you look at a Victorian OS map, you’ll find lime kilns everywhere, really everywhere, like four in a small town. The setting speed and cured strength, as well as how reactive to water, rely heavily on the geology. So a kiln from the nearby town might make a lime that sets hard and fast, whereas a few miles the other way gives you something softer and slower.
All of this is lost, with practically everything coming from Buxton (non-hydraulic) or Bordeaux (naturally hydraulic, NHL).
Again, it’s horses for courses, the range of performances available, even from the limited sources, from varying sand grading, lime strength and ratios is pretty vast.
Hot mixing is using quick lime (violently reactive with water) and wet sand. Not for the faint hearted and all good fun, till someone loses an eye!
Click to expand...
Judging by your response the op was right then . There is real lime after all. Thanks for putting my mind to rest!
 
Hi everyone,

Sorry to elbow in, but also seeking advice on lime plastering as working on a period property in the coming weeks and want to make sure I get the job done right.

Iv read up about the standard lime putty plaster mix, 'scratch coat, float coat, set coat' procedure...which seems somewhat straight forward...

But then what to do when plastering over old walls that have all been painted in modern day paints? As I understand with lime plaster PVA is a no go right?

Some walls have been patched up badly with gypsum, plan is to remove these area's, let the way breathe for a bit then re-plaster walls in lime.(building the deeper area's out with a bit of a scratch coat first)
Just confused on the paint situation and what best brand of lime plaster to order in, seeing a lot on google about 'Lincolnshire lime' not sure if anyone has used these products?
Read the suggestion of Anglia lime on this thread will check their website out.

Thanks in advance!
Jb
 
Jackbracks said:
Hi everyone,

Sorry to elbow in, but also seeking advice on lime plastering as working on a period property in the coming weeks and want to make sure I get the job done right.

Iv read up about the standard lime putty plaster mix, 'scratch coat, float coat, set coat' procedure...which seems somewhat straight forward...

But then what to do when plastering over old walls that have all been painted in modern day paints? As I understand with lime plaster PVA is a no go right?

Some walls have been patched up badly with gypsum, plan is to remove these area's, let the way breathe for a bit then re-plaster walls in lime.(building the deeper area's out with a bit of a scratch coat first)
Just confused on the paint situation and what best brand of lime plaster to order in, seeing a lot on google about 'Lincolnshire lime' not sure if anyone has used these products?
Read the suggestion of Anglia lime on this thread will check their website out.

Thanks in advance!
Jb
Click to expand...

when teh forum gets busy threads get lost so I reply with some dribble to bump them back up so hopefully someone will see it and help you :D
 
Jackbracks said:
Hi everyone,

Sorry to elbow in, but also seeking advice on lime plastering as working on a period property in the coming weeks and want to make sure I get the job done right.

Iv read up about the standard lime putty plaster mix, 'scratch coat, float coat, set coat' procedure...which seems somewhat straight forward...

But then what to do when plastering over old walls that have all been painted in modern day paints? As I understand with lime plaster PVA is a no go right?

Some walls have been patched up badly with gypsum, plan is to remove these area's, let the way breathe for a bit then re-plaster walls in lime.(building the deeper area's out with a bit of a scratch coat first)
Just confused on the paint situation and what best brand of lime plaster to order in, seeing a lot on google about 'Lincolnshire lime' not sure if anyone has used these products?
Read the suggestion of Anglia lime on this thread will check their website out.

Thanks in advance!
Jb
Click to expand...
Old walls with modern materials. Take the modern off and back to the old
 
Danny said:
when teh forum gets busy threads get lost so I reply with some dribble to bump them back up so hopefully someone will see it and help you :D
Click to expand...
Jackbracks said:
Hi everyone,

Sorry to elbow in, but also seeking advice on lime plastering as working on a period property in the coming weeks and want to make sure I get the job done right.

Iv read up about the standard lime putty plaster mix, 'scratch coat, float coat, set coat' procedure...which seems somewhat straight forward...

But then what to do when plastering over old walls that have all been painted in modern day paints? As I understand with lime plaster PVA is a no go right?

Some walls have been patched up badly with gypsum, plan is to remove these area's, let the way breathe for a bit then re-plaster walls in lime.(building the deeper area's out with a bit of a scratch coat first)
Just confused on the paint situation and what best brand of lime plaster to order in, seeing a lot on google about 'Lincolnshire lime' not sure if anyone has used these products?
Read the suggestion of Anglia lime on this thread will check their website out.

Thanks in advance!
Jb
Click to expand...

Hi Jackbracks,
The biggest headache with the ‘traditional’ lime putty/sand approach is the issue of carbonation, the absorption of CO2 that gives the plaster setting strength. This is totally separate to drying out, so you need control of suction, not letting the plaster dry too quickly.
Old lime plaster walls were often decorated with soft distemper, whitewash, if this is the case it’s worth trying a wallpaper steamer, this will soften the original paint enough that you can plane off the modern stuff with a Stanley type window scraper. Then just wash thoroughly to remove any old residue.
Cut out Gypsum repairs, dub out to flush and oversee the whole wall.
Not wishing to advertise too blatantly but our Limecote would do all of the above, available from Dot & Shaun at Lincolnshire Lime.
 
Hello again, a bit further advice if possible please. I have had a few people quote now for the job and 2 of them want to PVA the walls before lime plastering.

What are the consequences of this regards the breath ability of the plaster afterwards?

Also, they suggested that they would mix small amounts of cement with the mix to help it stick, again is this right/wrong or just the opinion of the guy doing this particular job?

Thanks so much in advance?
 
joemarsh20 said:
Hello again, a bit further advice if possible please. I have had a few people quote now for the job and 2 of them want to PVA the walls before lime plastering.

What are the consequences of this regards the breath ability of the plaster afterwards?

Also, they suggested that they would mix small amounts of cement with the mix to help it stick, again is this right/wrong or just the opinion of the guy doing this particular job?

Thanks so much in advance?[/QUOTE
Click to expand...
 
Absolute no to both, so that’s two less quotes to worry about.
PVA forms a vapour barrier, therefore stops breathability. Cement same.
There are plenty of ways of ensuring a sound background and control suction without resorting to glue. A good lime plaster should set with plenty enough strength without resorting to modern high strength cement.
That’s a no.
 
Ok that’s great thanks again, but kinda still leaves me with no one to do the job. This is a pain in the ass...

How long would it take to learn to lime plaster?
 
Jackbracks said:
Hi everyone,

Sorry to elbow in, but also seeking advice on lime plastering as working on a period property in the coming weeks and want to make sure I get the job done right.

Iv read up about the standard lime putty plaster mix, 'scratch coat, float coat, set coat' procedure...which seems somewhat straight forward...

But then what to do when plastering over old walls that have all been painted in modern day paints? As I understand with lime plaster PVA is a no go right?

Some walls have been patched up badly with gypsum, plan is to remove these area's, let the way breathe for a bit then re-plaster walls in lime.(building the deeper area's out with a bit of a scratch coat first)
Just confused on the paint situation and what best brand of lime plaster to order in, seeing a lot on google about 'Lincolnshire lime' not sure if anyone has used these products?
Read the suggestion of Anglia lime on this thread will check their website out.

Thanks in advance!
Jb
Click to expand...
go back to brickwork and start again/nothing modern
 
John j said:
Yeah with in 20 mins lol. How's you . Seen a post saying he done one
Click to expand...
I might be mistaken John, correct me if I am
wrong, but haven’t you posted a picture of your van recently? Sold now? :D

20 mins!!! That’s blooody good range ! (y)
Guess you have to recharge the scissor lift every time on arrival :maraca:
 
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