Three coat lime plaster-PT 2

[Anonymous]

First, thank you so much for the replies to my previous post.
I have tried the "contractor bag" stomp method and it was quite a change in texture for the better.

Follow up questions:
1. I tried throwing this improved looking plaster against the wall. It WILL NOT stick. Ploop--down on the floor. (The substrate has been sprayed previously). Does this mean I have to add more water to make the mix stickier? Or continue to knead in the bag for a longer period?

I asked the local supplier for lime putty (to help adherence) and he said that, he didn't have it, there was never any call for it and I was probably misinformed that I should need it. (!) That's the US for you! Must special order from afar.

2. By the time I had finished leveling, a longitudinal crack had appeared right down the center. What is causing the cracks to appear in the brown coat ? I get conflicting information-too much water causes cracks, too little water and the substrate pulls moisture out and causes cracks. ACK!

3. How much plaster do you push onto the wall from your hawk at a time and how much "Glide" do you get? By this I mean the amount of expected coverage per exertion with your trowel. Given the fact that lime is stiffer, I'm trying to get a visual of what a proper application should look like by the amount it will cover easily.

Anyway, I'm about to go to my work in progress again--more plaster repair. I will learn--darn it!

 

[Anonymous]

A lot of plastering is like flying a very old plane - as much is done by feel as by the book, and there's only a certain amount you can impart with just words...
Anyway.

1) The substrate has to be pretty wet. I usually give it a good soaking at least an hour before I start plastering, spraying so much that it starts to run and the material can't soak up any more. Then, just before I start plastering, it has another spray just to wet the surface again.
And the stuff itself has to be pretty well kneaded (I hesitate to say 'knocked up' to an American, but that's what we'd say in the UK) - it's one of those things where you know when it's right because its property changes; the plaster becomes slicker and stickier without being wetter (maybe watching a DVD would help - though I don't know what your friends and neighbours would think of 'plastering porn'!).
As for lime putty, it's a special order in the UK too - most ordinary builders' merchants have never heard of the stuff.

2) Cracks. Books could be written on cracking in plaster. A longtitudinal crack sounds unusual - generally the cracks follow the run of the laths (not to mention the spidery ones that go any old where, but we'll not mention those). Does it follow any underlying structure (a run of wiring, a piece of studwork)?
As for the general causes of cracks, too much water in the mix, too much suction in the substrate and not enough working of the plaster tend to be the commonest causes.
Different people work differently, but when I see a crack forming I go for it with a wooden cross-grained float, pushing the edges of the crack together and working over the surface with some pressure to compact it.
You can use a steel float, but you risk 'pulling' a lot of the lime to the surface, leaving the lower layers of aggregate impoverished.
Keep misting the new plaster with a spray - a couple of times a day for the first two days, and then once a day for the rest of the week. You can carry on working over the surface for two or three days, provided you wet it first. Good old-school plasterers could get a finish coat as smooth and hard as marble that way; wetting the surface with lime water and polishing it up (though they would finish off with a steel float when the plaster had been worked up with the wood, in order to get the final smooth surface).

3) Depends on the size of your float, the size of your hawk and the strength of your arm. A haired plaster will 'glide' less than an unhaired plaster, and a finer plaster will glide more than a rough old scratch coat. If you've got forearms like Popeye you might cover a patch of lath three times the size of your float with one 'sweep'. If you're like the rest of us, you'll conserve your energies and do it a float's area at a time. Obviously the finish coat will go further, but a lot of it is down to skill, strength, technique and the size of yer tools!

 

[Anonymous]

If you are trying to throw the plaster on, it sounds you you are trying to do harling. For this the "plaster" needs to be liquid, in a bucket, and flung on with a harling trowel. A very messy but quite satisfying job.

 

[Anonymous]

I can't believe that in the US important historic buildings aren't repaired with lime - there must be people who are doing it! Surely???

I will make enquiries...

 

[Anonymous]

I’m most probably talking a load of twaddle here, but having seen ‘harling’ mentioned, it put me in mind of EH & the NT and their many references to 'crapping' which got up my nose (it doesn’t take much!).

In the questionable "Roofs of England" campaign literature, the main booklet goes on about ‘crapping’ stones being used as a kind of anvil to dress roofing material. Now, since a lad I have always known such apparatus as ‘cropping’ stones – therefore, I thought could ‘harling’ really mean ‘hurling’ in Queens English and an innocent scribe took it down verbatim, not taking into account the rich brogue (or piss taking!) of local folk?

Academia arrogantly misinterpreting local dialect, or a well meaning bunch of amateurs believing they’ve discovered another language? Or what?

Bryan

 

[Anonymous]

Wouldn't surprise me in the slightest. If yew come from Suffolk, thin Harling is jist wot yew do with the stuff.
Reminds me of a rather Kensington colleague who was sent to cover a pit collapse somewhere in the Yorkshire coal fields.
In her copy was a reference to someone who lived in "Topper Pitt Lane". *sigh*

 

[Anonymous]

I think you'd have to look at the derivation and historic sources etc ...

Anyhow, here's something to read...


http://www.crockerltd.net/Overworked%20Plaster.htm

 

[Anonymous]

Anyhow - quite why these people worked on the Globe in Lunnon doing the lime I know not, but it proves that there is expertise over the water.



http://www.crockerltd.net

 

[Anonymous]

And here's Mike Wye's US distributor...


http://www.heritagelime.com/

 

[Anonymous]

This may be of interest


http://www.usheritage.com

 

[Anonymous]

It works the other way round as well I suppose, I don't know whether this is true or not but someone I knew swore it was; An officer exasperatingly asked an overworked orderly room clerk for some ‘pepper’ the fed-up clerk said ‘Black' pepper or White' pepper sir’? The officer replied; No! bleddy 'writing pepper’ you demned fuel!!

 

[Anonymous]

The 'Old House Services' part...

Historic preservation (they tend not to call it conservation is the US) isn't really confined to the UK - you just have to look! As with the UK...

There are preservation organisations in the US. I have a friend (now in the UK) who worked for one.


http://www.oldhouses.com/old-house-suppliers-services.htm

 

[Anonymous]

http://www.oldhouses.com/old-house-preservation-organizations.htm

 

[Anonymous]

Possibly a connection with the late and much-missed Sam Wanamaker, whose personal vision the Globe very much was.

 

[Anonymous]

Interesting that the original lime had failed.
Wonder why?

 

[Anonymous]

Once again, thanks for the detail, Gervase. And Evelyn, you went to a lot of trouble looking up information. I have a resource one state south of me (Virginia). It's just that not being a business, it is more expensive to ship than the cost of the goods. Quite annoying. Virginia Lime (my main source) does historic restorations as part of their business. However, there are no classes offered that I have found in lime plastering. Oh well. This online info is good.

I checked on my plaster job and it was cracked--did not adhere to the substrate despite all the wetting I did. I pulled it all out and made a new batch of slightly haired plaster for the brown coat, wetter than the last time and pummelled. THis batch did stick (Like snot-haha-thanks!) and I will see how this effort does in comparison.

I have both VERTICAL and horizontally laid lath of varying thicknesses, widths and spacing. My walls are therefore wavy. THe cracks were running in that general direction this time. I have experienced the spider cracks that run every which way in the finish coat. ALthough I closed up the cracks as soon as I saw them, they reappeared overnight. I think I will need a new wooden float (have been using metal) as the one I have just tears up my work rather than making a nice close finish.

 

[Anonymous]

The crocker site has some useful pictures of a French ditch being installed to dry out an adobe building...


French Ditch

 

[Anonymous]

This looked interesting too...

 

[Anonymous]

Maybe you know of the work of the Historic Richmond Foundation then.

There are website forums in the USA like this one connected to some of the info I posted. I wonder if anyone there can give any info on plastering? It may be that if you could make contact with others who aren't too far from you you could share expertise and problems. It may also be that there are professionals who would spend some time showing you how to plaster - for a fee. I know of people here who have done that. Could save money in the long term.



http://www.historicrichmond.com

 

[Anonymous]

The link this time!


http://www.crockerltd.net/underpinning.html.htm