marmorino fine lime top coat -- getting an even, satin sheen

Woods

Woods

Active Member
I'm trying to get a nice finish so that painting is not a requirement.

I'm using quicklime powder and marble dust (<300 micron) at a 1:3 ratio (after slaking this is closer to a 2:3 ratio). I'm using a marshalltown carbon steel trowel which is pretty well worn in.

What I'm after is a soft, even satin gloss, not a mirror. The problem I'm having currently is that the sheen is uneven. When I'm polishing, it seems that my blade misses certain patches. Pushing harder and using some water gets it more even, but then I get more discolouration and also too much of a mirror effect.

One thing that has been moderately succesful is using a polishing cloth when the plaster is reasonably firm but still green. This evens out the sheen a bit, but not enough. At this stage the plaster is too firm already to really have a stong effect. If it polish with the cloth earlier, it doesn't work because it scratches the plaster and brings too much of the marble dust to the surface.

My guess is that I need a much thinner blade and perhaps a smaller trowel too during the polishing stage when the plaster is firm but still malleable. I haven't worked with a flexi trowel yet so I was wondering if my assumption is correct before purchasing one.

I've also read in some places that since the top coat of fine lime plaster is applied so thin (<1mm), it is better to use a flexible blade for putting it on as well. Apparently it speeds up the spreading process. I'm not after the flattest possible finish ever because it really doesn't matter when we're talking less than a millimeter. My basecoat is dead flat within 1mm tolerance already, the final coat is really just about the aesthetic.

Perhaps I'm not skilled enough yet, but the marshalltown carbon steel doesn't get me the sheen that I'm after. Should I purchase a flexi and see what that does?
 
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marmorino - high pressure polish

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marmorino - lighter pressure polish 1

marmorino fine lime top coat -- getting an even, satin sheenmarmorino fine lime top coat -- getting an even, satin sheen
marmorino - lighter pressure polish 2
 
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marmorino fine lime top coat -- getting an even, satin sheen
lime + sand (0-1mm) -- light pressure polish

marmorino fine lime top coat -- getting an even, satin sheenmarmorino fine lime top coat -- getting an even, satin sheen
lime + sand (0-1mm) -- scouring + high pressure polish (gentle pitted effect)
 
Woods said:
I'm trying to get a nice finish so that painting is not a requirement.

I'm using quicklime powder and marble dust (<300 micron) at a 1:3 ratio (after slaking this is closer to a 2:3 ratio). I'm using a marshalltown carbon steel trowel which is pretty well worn in.

What I'm after is a soft, even satin gloss, not a mirror. The problem I'm having currently is that the sheen is uneven. When I'm polishing, it seems that my blade misses certain patches. Pushing harder and using some water gets it more even, but then I get more discolouration and also too much of a mirror effect.

One thing that has been moderately succesful is using a polishing cloth when the plaster is reasonably firm but still green. This evens out the sheen a bit, but not enough. At this stage the plaster is too firm already to really have a stong effect. If it polish with the cloth earlier, it doesn't work because it scratches the plaster and brings too much of the marble dust to the surface.

My guess is that I need a much thinner blade and perhaps a smaller trowel too during the polishing stage when the plaster is firm but still malleable. I haven't worked with a flexi trowel yet so I was wondering if my assumption is correct before purchasing one.

I've also read in some places that since the top coat of fine lime plaster is applied so thin (<1mm), it is better to use a flexible blade for putting it on as well. Apparently it speeds up the spreading process. I'm not after the flattest possible finish ever because it really doesn't matter when we're talking less than a millimeter. My basecoat is dead flat within 1mm tolerance already, the final coat is really just about the aesthetic.

Perhaps I'm not skilled enough yet, but the marshalltown carbon steel doesn't get me the sheen that I'm after. Should I purchase a flexi and see what that does?
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If you can get the Carbon absolutely razor sharp - you can do what you like with it. Achieve anything you're after on those.

For what you're trying to achieve, you'll need a 0.3mm stainless Flexi trowel.


And also try a Refina plaziflez (sponge backed) trowel. Using this at different times with different water quantities gives a broad range of sheens.


All to do with sound waves apparently. :cool:
 
haven't got it like a razor yet, but it's getting there; when you say that you can achieve anything with it, is it because a razor edge is more flexible? For my desired finish I polish pretty early so that I don't have to press too hard and I keep the trowel at a pretty shallow angle.

And yes, the feeling of the trowel sliding over the plaster as well as the sound... when your timing is spot on, it's addictive
 
Years back I did the venetian applicators course at Golden Trowell. We did all parts of the process with venetian trowels. These were hard so you coulld polish it and stainless steel so no marks were left. Carbon steel will leave stains.
 
What marmorino effect are you after?
The way I was taught was a very quick and easy application, leaving hollows in the top coat for a rough marble effect, not like a traditional venetian.
On all of these finishes a 5" trowel was used.
 
I'm trying to get it smooth without hollows, which works well enough. It's just the polishing that looks a bit s**t because it's uneven which is what I'm trying to improve. A smaller trowel might be better to spread it because it would be easier to avoid/fill the hollows
 
earth bau said:
Years back I did the venetian applicators course at Golden Trowell. We did all parts of the process with venetian trowels. These were hard so you coulld polish it and stainless steel so no marks were left. Carbon steel will leave stains.
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I don't believe I've noticed stains from the trowel tbh; maybe if the blade was very rusty but I don't think that has happened in my case before. Anyhow, I'm definitely going to try a different trowel for the sake of the gentle but even polish I'm after.
I do appreciate that a smaller trowel and stiffer blade would help with a high gloss effect, but especially on lighter colours, people have been saying that they do increase the chances of burn marks if you press hard. I've definitely had problems with that with my marshalltown.
For the effect I'm after, I'm hardly pushing when burnishing. If I press just a little too hard, it gets too glossy. Hence why I think a flexible blade would be more appropriate in this case.
 
Woods said:
And yes, the feeling of the trowel sliding over the plaster as well as the sound... when your timing is spot on, it's addictive
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Not listening to the sound, but the actual effect is a sound wave.

The plastic to steel to stainless steel each creates a different effect on the material, to do with sound. It can tamp the water in or out or finely scratch it to finish it differently.

(y)
 
bobski said:
Not listening to the sound, but the actual effect is a sound wave.

The plastic to steel to stainless steel each creates a different effect on the material, to do with sound. It can tamp the water in or out or finely scratch it to finish it differently.

(y)
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first time I've hear that mate. I thought it had to do with pressure. If you push hard, you compress the aggregates, forcing the water out of the gaps and the water has nowhere else to go but out to the surface. But then again, literally everything in the universe is electromagnetic vibration so in the end you're probably right anyway.

Did some more thinking about flexitrowels and here's my reasoning: marmorino is applied so thinly (.5mm - 1mm) that it dries too quickly to really take advantage of that effect. It dries within 10 minutes so you have to get it smooth as you go. With marmorino, you don't flatten a wall. You can only apply it to a wall that is already flat. So there is really no need for stiffer blade.

People have said that applying regular gypsum skim with a flexi looks amazing, leaving less ripples. The downside of course is that the british gypsum skim system is significantly thicker than marmorino coming in at 3mm on avg and probaly more if you go over a walls that has low spots. So with this system, you do need to make sure your skim coat is flat, so using a long speed skim and a stiff trowel makes a lot of sense. But many people have said that for the final polish, flexi trowels seem to get a better finish or at least make it easier.

Applying marmorino is kinda like wet troweling in the british gypsum system: you're not trying to get it flat, you're just applying an ultra thin coat and smooth it out immediately. It's very tricky to do with a large trowel and a stiff blade, especially because you're not supposed to make straight lines with your trowel, you have to vary your movements en use curved motions. Doing this with a 14" carbon steel, it takes ages to get all the lines out and since the plaster dries within 10 minutes, you lose a lot of valuable time.

In the stucco Italia instruction video where they talk about ventian trowels, the narrator said that interestingly his crew prefers to use a flexible trowel as it speeds up the rate of application significantly.

Also, when you look at japanese finishing trowels, they too have a very flexible blade. When they apply their final coats, the trowel floats over the surface of the wet plaster, almost leaving zero imperfections. When they come back later for the final polish, they have hardly any work to do. They also barely apply any pressure since they're flattening the plaster while it's wet.

I think I'm gonna get a medium sized japanese trowel with a pointy toe because I think there is no better tool to finish edges than this. The blade is also flexible, so it should make the application of the marmorino a lot easier to smooth out on the go.

And illustration of how the japs train to use this tool:

 
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British skims 'can' go on thinner than 3mm, and is often more reliable. Less chance of a tiger.

Them Jap trowels are good if you can get used to the handle format.

They have the best steel on the planet - bar none for me.

I've experienced a few of their tools and they have been outstanding.

(Going back to their Tamahagne iron ore used in their swordmaking - unique to Japan I think - to do with their Volcanic ash (from memory))
 
bobski said:
British skims 'can' go on thinner than 3mm, and is often more reliable. Less chance of a tiger.
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yeah I've heard a lot of guys put it on thinner going against the british gypsum "prescriptions" (aka they just wanna sell more product)
And yeah, in my humble opinion, a wall is straightened with a rule and a float, not with a trowel. It can be done with a trowel, but I don't understand why someone would want to "flatten" a skim skim coat over a decent float coat. Literally just put it on as thin as you can get away with and your wall will still be flat. Much quicker imo and less chance of imperfections, tigers and much better on the body. Especially with spraying and power floats these days... I think people should go back to solid plastering. For dotting and dabbing you need a lot of gear as well to create the seals anyway. If you wanna be efficient, just make screeds, then fill them in with a pump, rule off, power float with lots of water and one hard steel trowel to push some of the sand grains back into the wall; then brush off to get rid of loose sand. Then a <1mm skim. Oh, and do it all in lime while we're at it. And don't bother with a devil float. I literally cannot get my marmorino coat off after it's fully cured without even needing a key. It's bonded so well that if I try to get it off with a spatula, I'm diggin into the float coat in stead.
 
what I've been doing is priming my walls with very sloppy lime and sand; then I put on a thick base coat of course, sandy loam with just a tiny bit of lime added and straw of various sizes. After I did the first float, I lime wash it and float it again and give it a hard steel trowel. Because I essentially put more "fat" on the wall at the end and then float it again it gives a perfectly straight and relatively smooth wall with a very, very fine texture: the lime water fills in all the little spaces in between the course sand. When completely dry and cured, it's perfect for a <1mm marmorino skim.
 
a regular, devil floated sand/cement is too rough for a mamorino finish. You have to first put on a thicker coat to smooth out the wall and then do your normal two coat marmorino system. Much more efficient to float it with lime water in stead and arguably a much better bond because of the lime on the surface of the float coat.

sorry for the spam
 
little update:
0.3mm flexible japanese trowel arrived today. Applied a few test coats (lime + fine quartz sand 1:1)

Here are my findings:
applying the first coat is definitely faster and easier, there as less misses
The second coat is also very easy but... it takes much more effort to get the plaster straight. Even with a very thin coat, the waves are noticeable especially when you glide over the surface with the trowel at the polishing stage. This is consistent with what other venetian plaster experts have been saying: flexible trowel on the first coat, stiff trowel on the second.

The problem is that the plaster stiffens up within seconds when applying it to the wall. So you need to put some pressure on the trowel to straighten it out. Because of this pressure, the blade flexes, creating a smooth but not straight surface. I did a closer inspection of how the japs do it and they too tend to use a stiff trowel to apply and straighten it and come back with a flexible blade to polish. I have seen a few videos of japs who do apply very thin coats with a flexible blade; although in the narration they said that they believe you cannot do every stage of plastering optimally with just the single trowel.



To fix it, I took the float to the wall and scoured it with water. This got it straight again. Then polished it again with the japanese trowel and this did get a noticeably better finish. Much straighter and much more even in terms of shine.

So here's what I'll try next:

1. apply first coat with japanese trowel for speed, get most of the lines out but don't compress the plaster yet
2. apply the second coat with the marshalltown to press the second coat into the first one (wet on wet) to get it straight
3. polish with the japapnese trowel again

I'll see how this goes although I have to say, using the float to straighten it out works pretty well. The only "downside" is that you don't get the trowel mark movements in the wall. The variation in colour is much more even.
 
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Okay so... the flexible jap trowel is out. At best it's useful for polishing. When I switched back to the marshalltown it was very apparent I much quicker and the work looked better. Maybe I'm biased, maybe I'm just more used to that trowel but as it stands, the jap trowel just doesn't cut it. Too damn slow and a pain to get it straight. The plaster stiffens up so quickly that I end up putting an equal amount of pressure as I do with the marshalltown, but because the blade flexes, it isn't as efficient at pushing the overlapping pieces of plaster into each other. There's just no way around it: a 1mm marmorino coat on a masonry wall that was lime plastered is gonna require pressure. The marmorino just dries too fast. You have to apply one stroke, immediately flatten, move on to the next few strokes and then come back to the first stroke to further flatten/polish the surface. A flexible blade just doesn't cut it.

At best, the flexible blade is useful on the first layer. But even then, I would get a bigger flexible trowel to speed up the work. The first coat doesn't need to be flat and it's fine if it has a litle bit of texture to it. The important thing is just to get 100% coverage, no misses. Second coat definitely need the stiff blade to push both coats as well as the overlapping strokes into each other into a nicely compressed, smooth and flat surface.
 
Woods said:
Okay so... the flexible jap trowel is out. At best it's useful for polishing. When I switched back to the marshalltown it was very apparent I much quicker and the work looked better. Maybe I'm biased, maybe I'm just more used to that trowel but as it stands, the jap trowel just doesn't cut it. Too damn slow and a pain to get it straight. The plaster stiffens up so quickly that I end up putting an equal amount of pressure as I do with the marshalltown, but because the blade flexes, it isn't as efficient at pushing the overlapping pieces of plaster into each other. There's just no way around it: a 1mm marmorino coat on a masonry wall that was lime plastered is gonna require pressure. The marmorino just dries too fast. You have to apply one stroke, immediately flatten, move on to the next few strokes and then come back to the first stroke to further flatten/polish the surface. A flexible blade just doesn't cut it.

At best, the flexible blade is useful on the first layer. But even then, I would get a bigger flexible trowel to speed up the work. The first coat doesn't need to be flat and it's fine if it has a litle bit of texture to it. The important thing is just to get 100% coverage, no misses. Second coat definitely need the stiff blade to push both coats as well as the overlapping strokes into each other into a nicely compressed, smooth and flat surface.
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Get it sharp.
 
Woods said:
do you think I should take it to a wet stone?
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Some do.

I go old school on trowels, I rough it in on screeds and wet screed, if solid/set screed I soak it down.

The I find a blue engineering brick, same again, then sand paper to a finish.

If there's a cheap silvereline sharpening stone around - I'd use that...




I generally save my stones for fine honing my blades and chisels - I need to keep those stones true and flat.
 
Woods said:
thanks
and when you say sharp, do you mean at an angle like a knife? Or does is need a wider bevel, say +/- 5-10mm?
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Tradesman vary

Best to offer the trowel up to the wall/ceiling at the degree you would be trowelling/using at.....

Sharpen/mimic that angle.
 
cool, noted
I've been trying just now on wet screed for about 10 minutes but I don't feel much change yet. Any idea how long this would take?
 
Woods said:
cool, noted
I've been trying just now on wet screed for about 10 minutes but I don't feel much change yet. Any idea how long this would take?
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I've done loads.
14" trowel - 10 mins really

18" - 15 mins........

Aggressive action, steady speed, plenty of pressure.


DO NOT LET THE BLADE GET HOT!

Plenty of water and encourage a slurry.



Lots less pressure if it's a flex....
 
No

From new 10 mins gets it lovely to 'normally' work with.


If you've been using it for laying on and broken it in already, same again really.
 
bobski said:
No

From new 10 mins gets it lovely to 'normally' work with.


If you've been using it for laying on and broken it in already, same again really.
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well in that case, I think my trowel is already pretty decent. I've got another shitty trowel from years back when I first started out. I used it the other day because it's a bit smaller, thinking it would make it a bit easier to spread the marmorino but it didn't: it dragged and ripped the plaster off during the polish. The marshalltown doesn't do that.

I ordered some diamond sharpeners because why not; I'll try to get it a little sharper, just to see what it does. Thanks for the help!

So far the carbon steel remains the best trowel to spread the material. I think I just have to be mindful to not be skimpy on the first coat and apply it a bit more generously. This should help with the misses I think. And then on second coat go as thin as I can get it and compress the two layers and get it flat and smooth. I'm already getting a decent finish, but I'm not there yet
 
another update:

took my old shitty trowel, took it to the screed for 10 minutes and manages to get a definitive sharper edge. Then another 15min with sandpaper to really polish up that edge and make it as smooth as I could get it. Then I tried applying the marmorino once more and now that old shitty trowel finishes the plaster better than the marshalltown. It just glides over the stiff plaster like butter. I compared it to the MT and the MT definitely dragged more. I felt up the edge of the MT and it isn't as smooth as my old shitty trowel.

For some reason my old stainless steel shitty trowel is much easier to sharpen and polish than the MT carbon steel. Anyways, I can 100% verify that a sharp but also smooth edge on the blade of your trowel drastically improves the finish. The difference is night and day. Thanks @bobski for pushing the sharpening. I used the shitty trowel right after I took it to the screed and it wasn't good at all. But then it dawned on my that the edge was sharp yes, but not at all smooth. So then I took it to the sandpaper, tried again, and now it worked like magic. So it's not just sharpness but also smoothness that is the key. I think it makes a lot of sense to carry some very fine sandpaper on every job to quickly give your trowel a little polish before you finish the plaster. The proof is just in the pudding. Now I get why ventian plasterers sand their trowel right before the final coat.

marmorino fine lime top coat -- getting an even, satin sheen
 
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