Hoping someone with any experience of this plaster can offer some advice. My lovely plasterer with no experience of lime has been giving this a shot. Got the base layer of baumit RK70 done without a problem. Has now attempted the first wall with the glatt finishing coat (under coat completely dry) and has really struggled. The main issue is that there seem to be small bubbles in the plaster on the wall. He has just been mixing up another bag and again these little lumps (which seem like bubbles) are appearing in the mix. Does anyone have any tips on exactly how this stuff should be mixed and applied? I’m really struggling to find any info online and the official documents tell us very little! All help massively appreciated.

Thanks so much for getting back to me. The base coat has been drying for a couple of weeks now so I’d be surprised if it’s got any moisture left in it. He’s in just now and has tried it much wetter than his first go but the bubbles still seem to be an issue. Would you mind going over your process of using it? He’s finding it completely different to the base coat which he managed fine with. Should it be left for a while once on the wall and the floated with a sponge or a trowel? He’s getting it flat but the bubbles are still there and so he’s struggling to get it smooth. Also wondering if he’s just not mixing it enough. Or maybe too much? Worse comes to worse he reckons a good sand and the clay paint we are planning to use should be enough to cover any imperfections but I feel bad that it’s proving a bit frustrating for him!

Sorry, you said: ''Would you mind going over your process of using it? ''

Mix really runny, get it on the wall (it''ll be so thin you can hear the trowel grating on the RK70 below). When it starts 'pulling' throw a bit of water on it and trowel up. Leave to harden (not very long if the base-coat is sucking) and go over with another coat, and trowel up as final finish. I cannot remember whether I wetted the base-coat this time. It really sounds like the problem is the lumps, which I have never experienced. What's the date on the bags? (would be amazed if it was 'too old' given that I have used old Glatt, but worth a check.

Back To Earth (WF and plaster supplier) say this:

How is it used?
Baumit Klima Glatte is mixed by adding to clean water and leaving to sit for 5-10 minutes after which point it can be whisked in to a smooth, creamy, lump-free consistency.
This is applied to the surface with a steel trowel at 1-2mm thickness and then left to stiffen for around 2 hours (may be longer in cooler, more humid conditions).

...and Baumit say this:

Put clean water in a clean bucket or mortar trough. Sprinkle with Klima GlatteW (Fino) and leave for 5 - 10 minutes, stir with a suitable
stirrer (eg whisk) until a lump-free, creamy processing consistency is obtained.
Tip: To achieve an even creamier consistency, immerse Baumit KlimaFino 2 - 3 hours in advance, stir and stir again before use (about
8 hours pot life).

A second, thinner and wetter layer is then applied and used to finish the plaster, bringing the total thickness to around 2mm.

Good luck with the supplier. I was wondering about a 'rogue' bag. How many did you have? Perhaps the supplier would give you another FOC (tho' carriage is the killer).

Will be doing some touching-up with glatt in the next few days. Will see if I get any issues. By the way, manufacturer's recommendations and Best Practice aside, I have only ever mixed glatt how I would mix RK70, insofar as I just put water in a bucket and then add powder till the consistency is right (though much thinner than RK70). For me, no leaving it to stand, re-whisking, and it's always been OK (10+ years of using it). Watch it go wrong now!

@RosieB, I hope you get it sorted. I'd definitely try to get the original supplier or Baumit to give you a new bag/bags.

Have you been in touch with a local rep, or with 'central office' (not the German one!)? They have regional reps. Ask for a site visit. There seems to be something odd going on. I have *never* had Glatt harden rapidly in the bucket. Very odd. Good luck, and keep us posted.

Never used the stuff, but the data sheet ( https://baumit.co.uk/files/uk/pdf_files/pds_klimafino___klimagl_tte_buk_en_42360.pdf ) says "Tip: To achieve an even creamier consistency, immerse Baumit KlimaFino 2 - 3 hours in advance, stir and stir again before use (about 8 hours pot life)" and the descriptive web page says "Smooth lime with high hydraulic composition ...". That doesn't seem to match some of the descriptions of how to use it.Am I looking at the right product?

OK, so this is going to make @RosieB and her plasterer feel fed up, not better, but I have just done the glatt coat on a bit of patching (only about 40mm x 1200mm!) under a cill-board. Hand-mixed (far too much!) glatt for not very long, did 2 coats only about an hour between (1st coat over RK70 sucked v hard) and it all seems fine. (Will go up later and see if I have any air bubbles). Definitely not looking to score points, rather to indicate that it really sounds like something wrong with your Glatt. Any news from Baumit? @RosieB, would you like me to send a link to your thread to the last name I have as my 'local' Baumit rep? Can't guarantee a reply as they seem to change now and again. Or you could contact them directly:


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Thank you for all those contacts though Nick, I might try reaching out to one of the technical training advisors and see if they can be of any more help.

Sorry to read of your problems. - From this distance all I can recount is how glatt is used over here.

Here walls are rendered not plastered, done by the builder. after that the decorator comes in and applies glatt to the walls to make a smooth surface for painting. The decorator doesn't skim the walls as per UK fashion but rather mixes the glatt to a runny cheese sauce look alike and scrapes the glatt on to the wall with a float. Note it is a scrapes on to the wall. The action is to fill the pores and dips in the render left by the builder doing the render. It is the thinnest of coats. The glatt is mixed by hand in small quantities and the mixing tub and tools are thoroughly cleaned before mixing a new batch to avoid transfer of lumps. Prior to the application of the glatt the wall is scraped with a hand tool with blades sticking out from the board to scrape off bits and pieces. Usually 2 coats of glatt are applied before painting.

That is how the stuff is used over here. It won't be put on thick enough for air bubbles to form. If your base RK70 is smooth enough you might want to try using it the way it is done over here. (I have successfully used glatt that was 2 years old from an opened bag)

The product that is sold here is
https://baumit.hu/termekek/termeszetes-lakoklima/termeszetes-lakoklima-alkategoria/baumit-klimaglatte

and the product description translates to

vapour permeable calcareous glatt material

Natural calcareous grouting material for interiors, for concrete, lime, lime-cement and Sanova renovation plasters, with manual and machine application, to produce a grouted surface, in one or more layers.

Smooth surface
Pleasant indoor climate
Climate control and vapour permeable

What's the wall surface that the plaster is being put on?

Wood fibre board, yes.
The whole upstairs had to be stripped/allowed to fall back to the bare bones as a result of slow roof leaks we were unaware of when we bought the place. Replaced the roof and then I installed diathonite cork/lime insulating plaster on to the brick. That was left for months while we tried to figure out next steps/ waited for new windows to be installed. Followed by gutex wood fibre. RK70 on top of this. And then the glatt. Our plasterer was not meant to be doing the line originally but took it on after we were let down by the only person we could find to do it. He was fitting us in between other pre-booked jobs and so the RK70 was sitting for a minimum of 2 weeks before the glatt was applied. The last lot he tackled yesterday had been drying for almost 4.
Who knows?! A good sand and it will all be perfectly fine when painted so I’m not too bothered but it would be great to figure it out for future reference.