Microcement application/ lines

[Micro6]

Hi all,

New to the forum and wondered if if anyone else is experiencing the same trowel issues I am having with microcement.

When applying the material I am getting lines. See images..

I have tried less pressure, more pressure but no change.

Has anyone else got this or is it just me?

Cheers!

 

[ptolemyworks]

Those are chatter marks. They happen when the trowel hits small pieces of aggregate in the microcement. Each one of those lines is caused by the trowel hitting a little piece of sand and skipping over it. How many coats are you doing? With microcement you usually want to do 2 or 3 coats, then sand between each one. By the final coat, if your are using a medium or fine microcement you shouldn't get a lot of chatter marks (depends on the microcement). If you still get any you can pick out the little bit of grit and smooth over it.

 

[Micro6]

Those are chatter marks. They happen when the trowel hits small pieces of aggregate in the microcement. Each one of those lines is caused by the trowel hitting a little piece of sand and skipping over it. How many coats are you doing? With microcement you usually want to do 2 or 3 coats, then sand between each one. By the final coat, if your are using a medium or fine microcement you shouldn't get a lot of chatter marks (depends on the microcement). If you still get any you can pick out the little bit of grit and smooth over it.

Hi,

Thanks for your advice here. Yeah, it seems that is exactly the issue. I am normally doing 4 layers. 2 base coats and 2 top layers. (Sometimes 1 medium and 1 fine, or 2 medium). I have been sanding between layers but they still highlight faintly on the end result.

Using a Mirka Deros too, with decent grit pads, but maybe a bit more time needed sanding could fix it.

Cheers!

 

[plas1]

Hi,

Thanks for your advice here. Yeah, it seems that is exactly the issue. I am normally doing 4 layers. 2 base coats and 2 top layers. (Sometimes 1 medium and 1 fine, or 2 medium). I have been sanding between layers but they still highlight faintly on the end result.

Using a Mirka Deros too, with decent grit pads, but maybe a bit more time needed sanding could fix it.

Cheers!

Hi mate

What Brand do you use out of Interest?Also what pads are you using?If you don't already try diamond pads as it will knock it back alot easier but depending on the strength of micro it could cut through easy as some of the micros out there are very soft.I use an epoxy based so nothing else cuts it back than diamonds.

 

[Micro6]

Hi mate

What Brand do you use out of Interest?Also what pads are you using?If you don't already try diamond pads as it will knock it back alot easier but depending on the strength of micro it could cut through easy as some of the micros out there are very soft.I use an epoxy based so nothing else cuts it back than diamonds.

Hi mate,

I'm using 2 different brands, depending on what the customer is looking for and the area to be surfaced.
NovaColor epoxy is one and the other is a resin based supplier (rebranded).

NovaColor is good quality stuff but a bit more expensive. What are you using?

I'm using Mirka Abranet pads. Depending on the need I also use Abranet Ace.

I've only been doing it a year so still tweaking some things till I find a good quality product / ease of use ratio.

 

[ptolemyworks]

Doing 4 coats is great, as long as they aren't too thick. Microcement wants to be applied very thinly, just to the aggregate. If you apply too many coats too thickly it can remain soft. It's hard to tell from the pictures, but when you apply your coats are you doing small semicircular movements? That's essential for getting the final look organic rather than obviously hand applied.
Also, try using silicone carbide sanding pads. They're more expensive but last a lot longer and are more effective for eliminating lines and chatter marks.

 

[ptolemyworks]

One more thing. A product I really like is Pastellone, made by Stucco Italiano and sold by Cait Whitson. It's a much more natural looking product, lime based. Some customers think microcement looks plasticky and prefer a more mineral based product. Pastellone is based on the Italian lime polished floors.

 

[plas1]

Hi mate,

I'm using 2 different brands, depending on what the customer is looking for and the area to be surfaced.
NovaColor epoxy is one and the other is a resin based supplier (rebranded).

NovaColor is good quality stuff but a bit more expensive. What are you using?

I'm using Mirka Abranet pads. Depending on the need I also use Abranet Ace.

I've only been doing it a year so still tweaking some things till I find a good quality product / ease of use ratio.

Hi mate

Sorry for late reply.

I only use Forcrete as I personally think it's the best out there.

Good luck on your journey

 

[Woods]

if your material has bigger aggregates (which to me it seems like yours does) you wanna apply the first layer a little thicker. Still thin, but rather than trying to scrape off the excess, you wanna gently float over the plaster with a closed trowel. You wanna leave some body to it and just get it fairly neat and get rid of most of the lines. Some plasterers suggest a flexible trowel for the first coat because it leaves less lines and follows the contours of the wall. Your first layer is not about getting it flat or perfectly neat although you don't wanna make a mess either.

When you work with a material that has larger aggregates, the first layer is there to act as a base for your second coat. When you apply the second coat, what you want to do is press the aggregates into the first layer and focus on getting it really neat as you go. This means that your first layer can't be too dry as you apply the second coat. They call this technique "a fresco".

If you apply your second layer on a first layer that is bone dry, you cannot embed the aggregates which results in chatter marks.

 

[plas1]

if your material has bigger aggregates (which to me it seems like yours does) you wanna apply the first layer a little thicker. Still thin, but rather than trying to scrape off the excess, you wanna gently float over the plaster with a closed trowel. You wanna leave some body to it and just get it fairly neat and get rid of most of the lines. Some plasterers suggest a flexible trowel for the first coat because it leaves less lines and follows the contours of the wall. Your first layer is not about getting it flat or perfectly neat although you don't wanna make a mess either.

When you work with a material that has larger aggregates, the first layer is there to act as a base for your second coat. When you apply the second coat, what you want to do is press the aggregates into the first layer and focus on getting it really neat as you go. This means that your first layer can't be too dry as you apply the second coat. They call this technique "a fresco".

If you apply your second layer on a first layer that is bone dry, you cannot embed the aggregates which results in chatter marks.

Every Microcement should be applied to the grain,regardless of the grain size.

Applying it thick wont cure properly and you will find it skins over appose to curing and creates a scab when sanding back.

Some manufacturers have a medium or smooth coat after base coat to achieve different effects but as above still to be applied to the grain.

 

[Woods]

Every Microcement should be applied to the grain,regardless of the grain size.

Applying it thick wont cure properly and you will find it skins over appose to curing and creates a scab when sanding back.

Some manufacturers have a medium or smooth coat after base coat to achieve different effects but as above still to be applied to the grain.

does microcement absolutely require sanding? Why do you use this over just traditional marmorino then? You can dope it with metakaolin, casein, talc powder, calcium sulfate and cellulose fibers if you're worried about strength. You also add beeswax emulsion and marseille soap if you want more water repellency. No sanding required.

No wonder Mortex and similar products cost an arm and a leg.

 

[plas1]

does microcement absolutely require sanding? Why do you use this over just traditional marmorino then? You can dope it with metakaolin, casein, talc powder, calcium sulfate and cellulose fibers if you're worried about strength. You also add beeswax emulsion and marseille soap if you want more water repellency. No sanding required.

No wonder Mortex and similar products cost an arm and a leg.

Yes all Microcement should be sanded between coats to keep it compact.It won't give the same strength as Microcement.Well it may with some Microcements as there are alot of soft ones out there.

Marmarin

Also you get what you pay for for products as you do anything.

does microcement absolutely require sanding? Why do you use this over just traditional marmorino then? You can dope it with metakaolin, casein, talc powder, calcium sulfate and cellulose fibers if you're worried about strength. You also add beeswax emulsion and marseille soap if you want more water repellency. No sanding required.

No wonder Mortex and similar products cost an arm and a leg.

Microcement is a total different product to marmarino or any Venetian plasters.Marmarino is not suitable for shower enclosures or where there is constant water however Microcement is and is fully complete waterproof.

Also Microcement is alot stronger than marmarino or any plaster even travertine or intonochino etc.

 

[Woods]

I agree it's a different product; it's useful if you want to seal something completely
marmorino can be suitable for bathrooms but it depends on the ingredients and application. Has been done for thousands of years.
Of course in 99% of "modern" homes it doesn't work because the walls aren't designed to dry out efficiently; everything is sealed. In such a system, porous plasters have no function and can do more harm than good. But if your walls do dry out efficiently (brick and lime mortar), a marmorino/tadelakt soap/wax finished plaster works perfectly.

I will add this: if you get even a tiny crack in your microcement, you're f**k*d. Moisture will get in and behind the wall and in time it will mold and eventually fail. And don't get me started on power outages. If you get a few days of power outage, your ventilation system stops working and well, then you're f**k*d