how to plaster a wall (first coat)


start with a bare wall, loose material removed, brushed down and lightly wetted .


apply plaster around the edge like a frame ; i got the left hand one flat then some horizontal ribs to project the levels to the other side, then complete the right screed


fill in the blank areas bring level with the frame. This is only the first coat but it is brought level, if it isn’t what is the point? After trowelling I went over it with a couple of straight edges; one long, one short – up and down and side to side sawing movement across the surface just to take off the high spots.


key with a comb ready for the next coat, which will be easy as this is already more or less level, some shrinkage will cause this first coat to be less level than it was at the start, this wont crack because there is enough hair in it to stop that but it will still shrink.

So there you have it, a very small bit of wall I know but the principles are the same all the time, get the plaster level with the first coat not the second, the second coat just brings the plaster to the correct depth. If your first coat is not level what was it’s purpose?


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my Japanese plastering trowels


These are the only plastering trowels I use.  Starting at 9 on the clock: a medium sized Jigane laying on trowel,  next a little really flexible polishing trowel, at the top a larger jigane, recently used for laying on the finishing plaster, at 3 a medium sized Honyaki finishing trowel which I also use for the finishing plaster. at the bottom a smaller Honyaki which I use both for laying on and compacting the finishing plaster, then at 8 on the clock, my new Honyaki trowel solely for compacting and smoothing. Also three small corner trowels.




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Renovating old domestic plaster surfaces


applying the first coat of finishing plaster

A testing job for my own recipe JBLime finishing plaster but one that any other lime plaster may well have not managed so easily.

The walls are generally old lime plaster but have been painted with emulsion, wall papered and patched and in places over skimmed with nice pink gypsum. The main patches were done with limelite.

In the picture you can see the new finishing plaster going on (the darker grey)  Areas where limelite was removed and replaced with a new lime plaster and the green is the wall prepared with a grit primer after the wall paper was removed.


The fire place was a bit of fun. The three walls are gypsum apart from the one on the left which is half plastered in cement. They were all painted with emulsion which was easily scrape off. I keyed the gypsum to get a good mechanical fix for the plaster skim.

The wall can be seen with the grip primer, I did not want to entirely rely on the grip coat so I also keyed the old plaster with my spiked roller (lime plastering plasterboard. with the correct tool and material it works well.)  which has come into its own for breaking through the surface of painted plaster. It takes a fair bit of force but it soon does the job and gives a decent key without making a great lot of damage, it is also useful for stressing the plaster all over so that any loose or suspect bits of plaster are soon found out and can be replaced.


The final coat applied, all smoothed and flattened. It is still drying here and there; on a job like this, with all the different substrates to contend with, drying is very uneven. The new lime patches at the bottom reached trowelling condition within a couple of hours, the plaster on the cement took two days. The plaster on the gypsum was reasonably quick being trowelled the following day, which just called for patience because as I said, the left hand side was gypsum down to half height then cement, which, to add a little extra difficulty, was set back from the gypsum half about 3mm so it needed and extra coat of plaster. The rest of the grit primed plaster reached trowelling condition about 24 hrs after application.

When I say trowelling I mean flattening, smoothing and compacting.  The window of opportunity for trowelling is quite wide, although there is a sweet point when it is perfect. If you try too early the plaster can form the occasional little bubble and it is very difficult to remove the trowel marks, trowelling too soon is best avoided but there are times when you need to do it, this is when I know that if I leave the trowelling overnight it will go too far and be almost too dry for the trowelling to be easy the following morning, in that situation I can carefully trowel the plaster smooth and then in the morning all I need do is go over again for the final compacting and smoothing.

Of course all this is so much easier when the plaster is flat, undulating plaster is such a chore and for that I find I have to use the really flexible, venetian plastering type trowel, but for all other plastering the trowels I use are rigid, that appears to be the Japanese tradition, rigid trowels for laying on, with practice you can get the plaster pretty flat without the need for floating, and even on this job, which was mainly skimming I used a very rigid Japanese Jigane trowel.  (


Honyaki finishing trowel – the blade is quite rigid with only the slightest amount of flexing under pressure. It compacts and flattens to achieve a very hard wearing lime plaster surface.


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Recipe for course stuff

My recipe for course stuff:

3 parts lime putty

1 part horse hair about 30mm long

6 parts sharp sand


put the lime putty in a mixing tub such as a large trug, add the hair and stir it in so that the hair disperses. add half the sand mix with a plaster whisk then add the rest of the sand and mix again.

Some hair will get tangled on the whisk this needs to be taken off before it is used again.

I use a propellor whisk from Refina

MR8 120G Impellor Paddle this grabs less hair than a basket whisk.



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Tricks of the trade number 1


This wall, being damp, had over the years been repaired with a host of materials, plaster board, metal lath and cement, universal one coat and gypsum. All that was removed and the wall was pretty undulating and there was a lot of depth to be made up. To make things easier I made five vertical ribs with the plaster and brought them up to the required level for the first coat. I was pushing it a bit as it was plain at least three coats where required but time was not available so I had to do it in two coats and a finish coat i.e a scratch and a float coat. So given the depth I opted for this age old method; with the ribs giving me clear indication  of how much depth there was I got some plain terracotta roofing tiles and built up the thickness with them.

dubbing out

dubbing out with broken roofing tiles

The tiles take the place of some of the plaster and the ribs make sure you don’t pack the wall out too far, the ribs were all on the same level so that I knew that I would end up wit a flat wall.  There were places were no packing was needed and places were two layers were needed. but the process was easy and quick.

make sure the tiles are tapped deep into the plaster

At the end the wall was level and the next day I was able to put the float coat on. Thereby successfully applying an inch and half of plaster in two coats with no risk of cracking.

This technique has been used for centuries and can even be seen in Pompeii.

ready for the float coat

ready for the float coat

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Lime for beginners training course. Cotswolds Rural Skills.

So another course has come and gone.


We had fun. and sun.

and got a lot of work and learning done.

So what happens on a John Byrne led lime workshop? We start with an introduction to the ingredients: limestone, quick lime, hydrated lime (lime putty), sand. mortar, old mortar, and completing the lime cycle – stone again.

Calcium carbonate, calcium oxide, calcium hydroxide, calcium carbonate

we mix up some mortar, talk about recipes, and where to buy ready mixed mortars ,and when and how, we add horse hair to make  plaster. Then we practice pointing and practice plastering, dubbing out the wall, getting it level or at least not so uneven. The following day we look at finishing the pointing, pressing back and brushing off, we apply finishing plaster to our first days plastering,  smoothing the surface, plastering corners  All this is done on a real building not in some workshop on a concrete block wall, all the work produced by the participants  becomes part of the fabric of the building and builds, course on course, until the building has been repaired, pointed, plastered. The only recycled work is the Plastering on a lath panel. but its good to be able to see both sides.  Then we have a break from plastering and look at limewash and its pigmenting and application, and we end with lime slaking, which lays down lime for the next course.




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I like this too

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my favourite plastering technique video

A master of plastering – I aspire to this level of dexterity and cleanliness!

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Plastering with my own Lime Rich Mortars



I have been lime plastering for a number of years and over those years I have usually bought in ready mixed course stuff and fine stuff, however I have recently developed my own finishing plaster as mentioned already and I think it is the best finishing plaster I have ever used and it should be as I developed it for that purpose.

Recently I began to think about the course stuff, that too could be better and I have just done a job where I made my own.

I have been thinking for some time that there is never enough lime in the mix. Most mixes nowadays are in the region of 1 part lime putty to 2 1/2 parts aggregate and in the Cotswolds that is usually a mixture of sharp sand and Cotswold stone dust. For me that is not enough lime.

The recipe I am using at the moment is 1 part lime putty to 2 parts sharp sand, this gives a really sticky mix to which can be added a lot of hair. It is a happy fact that when you add a lot of lime, the plaster will tend to crack as it dries out, but being so sticky it will hold more hair and that hair stops the cracking. This is a rule worth remembering, the stickier the mix the more hair it will take, of course the best way to get a sticky mix is to add more lime putty – not more stone dust.

Lime putty has never been easier to produce so why skimp on it?

Once you have a really sticky plaster the technique of plastering changes – you don’t really spread it on directly off the hawk but apply it to the wall in dollops and then spread it flat, it’s amazing how easy the process of plastering becomes when the mix is right (and how difficult the job is when the mix is wrong).

Another penny dropped the other week when I saw a scratch coat of render that hadn’t rendered the wall flat, it was almost as bumpy as before. there is no point in this, if you are after a flat wall the scratch coat is the time to get it flat – dub it out to even out the surface, apply the first coat, get that as flat as possible and any undue thickness, due to the undulating surface might well crack a little, even with plenty hair, but this cracking is in the first coat and as long as the plaster hasn’t become detached from the wall (which can happen) it is of little consequence. Once you get it flat, and you can use a straight edge such as a rule, or derby float for this, then you scratch it ready for the next coat.

Scratch coat applied

The next coat is now easy to apply, it is of even thickness, dries even and is easy to get flat. This second coat is brought up to within 4 mm of the final level and trowelled or floated flat, corners crisp or nicely rounded.

second coat ready for the finishing coat

The finishing coats can then be applied in a couple of passes and trowelled flat and smooth.  By getting the wall flat as soon as possible makes every other stage really easy and efficient.

All of this is so much easier with a mix with 33% lime putty by volume and loads of hair – you really do need to be able to see the hair in the mix – they need to be really obvious – horse hair is best, don’t bother buying the nicely wrapped in string stuff, find yourself a friendly horse owner or two and ask them for the hair off their horses. It’s cheap and it works great.

so there you have it my own recipe from now on is a minimum of 33% lpbv (lime putty by volume) for backing coats and a minimum of 60% for the top coat.

Lime rich, fibre rich mortars for excellent results

(The blue colour is caused by the slate granules used in recipe for the top coat – 66% lime putty : 33% slate granules – it will dry white of course)



just needs the dado rail and fire surround fitting… and the skirting painting.

by John Byrne ~ Artisan Lime Plasterer

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JB Lime Finishing Plasters

The first field trials began this week. After a number of weeks of trials, adjusting recipes and readjusting recipes I sent 130 litres to the Cotswolds to be applied by someone else outside of my own house.

The feedback was most gratifying:

“Easy to use” I gave it one good coat and then kept going back and trowelling it up. It is very nice to use, closes in so well you get a lovely flat finish – it’s the best I’ve used.”

There is a facebook page  now as well –

I supplied it at 58% lime putty by volume. (that’s 10 units of lime putty to 7 units of aggregate). I won’t be using all this 3:2, 1:2 etc I want to be clear about just exactly how much is lime putty without any ambiguity.








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