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General: Plastering tips

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  1.  
    Partway through my renovation and have now parted company with the builder. Too many issues to list here but have noted some previous frustrations in past threads. Structural work is complete so outstanding is plumbing (have a decent local plumber lined up), window installation, plastering, carpentry and second fix electrics. Not in a panic now as I will be stuck in a rental contract for next four months at least. Many lessons learned about dealing with building trades if anyone is thinking of embarking on their own project!

    Anyhow, in the interim I have been getting on with trying out the insulating plaster (Bauwer light). I have had some success so far (as a novice) and half tempted to keep going given the quotes I have had back for application to external facing walls. Another factor is that massive surplus I now have - the original order contained 90+ bags of out of date Light which were replaced but old stock not removed. The old stuff is not great but useful for filling in big holes etc.

    So far I have completed two walls in the kitchen area so that the plumber can get going. Applied 40mm-ish of the Light render, and then Bauwer Finish embedded in mesh. I used a speedskim to flatten top layers. The final result is not bad but I had trouble getting a smooth finish on the Bauwer Finish coat. It does contain some cement so maybe hardens faster than a pure lime based plaster? I am looking for recommendations on what to use a skim coat over the Bauwer. I know Nick has mentioned the Baumit plasters as being very user friendly so I am looking in that direction. Ideally something I could use all around the house i.e. over both the Bauwer, some areas of WF, and also plasterboard (after appropriate primer). Does such a thing exist? Also any tips on how to finish (timings!) as most of my web-based learning is from guys using either multi-finish or pure lime putty, not much inbetween.
  2.  
    I never used the Bauwer finish. I found the Bauwer Light really quite difficult to use - a bit like trying to trowel chewing-gum!! I finished over it with Baumit RK70. For base-coat if uninsulated plaster required, use Baumit RK38. If you want a really glass-smooth finish use RK30 ('Kalkin Glatt') over the RK70. For a coarser 'cottage' finish RK70 can be the finish coat.

    Hard to help you much on timings because a lot depends on temp, humidity and so on. For the RKL70 wait till it is quite 'stiff' but not hard. Then get a damp car-washing sponge and rub in a circular motion. You are aiming to 'move custard behind the skin'. 4 days later you can apply the Glatt. You will almost certainly need 2.5 coats of RK70 if you are reinforcing with mesh - Initial toothed coat into which you 'float' the mesh (Don't push it back - it wants to finish halfway through the 1.5th coat). Wait an hour or so for the toothed coat with mesh to stiffen very slightly, and go over the mesh more-or-less 'wet on wet'. Trowel as smooth as you can. If there is absolutely NO mesh 'ghosting' you may be able to stop there and proceed to the sponging in time, but I usually find another 3mm or so is required, then the sponging. Some sources suggest total plaster fininsh even on top of woods-fibre board should be 10-15mm. I confess mine is usually nearer 6-8-10. Just tapping my wall as I type and it's solid as a solid thing.
  3.  
    Thanks Nick. That is exactly the information I was after. I know it is difficult to predict the timings but for sponging the RK70 are we talking 'hours'?
  4.  
    Yes, hours. Hard to say how many as it will depend on the weather, the 'tightness' or leakiness of the house and other unknown variables. I usually tell people it'll be ready to sponge up at 04.30 a.m. the next day, when you are not due on site till 11.00 a.m.! I try to get the final base-coat done as early as possible in the morning so there is a cat in hell's chance of sponging up before you leave. Any 'dragging' and you know it's too early. Soft enough to move but hard enough to 'bully' into place is the watchword.
    • CommentAuthorkristeva
    • CommentTimeSep 9th 2021
     
    Posted By: modernvictorianPartway through my renovation and have now parted company with the builder. Too many issues to list here but have noted some previous frustrations in past threads. Structural work is complete so outstanding is plumbing (have a decent local plumber lined up), window installation, plastering, carpentry and second fix electrics. Not in a panic now as I will be stuck in a rental contract for next four months at least. Many lessons learned about dealing with building trades if anyone is thinking of embarking on their own project!

    Anyhow, in the interim I have been getting on with trying out the insulating plaster (Bauwer light). I have had some success so far (as a novice) and half tempted to keep going given the quotes I have had back for application to external facing walls. Another factor is that massive surplus I now have - the original order contained 90+ bags of out of date Light which were replaced but old stock not removed. The old stuff is not great but useful for filling in big holes etc.

    So far I have completed two walls in the kitchen area so that the plumber can get going. Applied 40mm-ish of the Light render, and then Bauwer Finish embedded in mesh. I used a speedskim to flatten top layers. The final result is not bad but I had trouble getting a smooth finish on the Bauwer Finish coat. It does contain some cement so maybe hardens faster than a pure lime based plaster? I am looking for recommendations on what to use a skim coat over the Bauwer. I know Nick has mentioned the Baumit plasters as being very user friendly so I am looking in that direction. Ideally something I could use all around the house i.e. over both the Bauwer, some areas of WF, and also plasterboard (after appropriate primer). Does such a thing exist? Also any tips on how to finish (timings!) as most of my web-based learning is from guys using either multi-finish or pure lime putty, not much inbetween.


    Hi MF, I seem to be in a similar situation to you. Having had decent success dubbing out sizeable areas with a base coat lime I was tempted to try a skim. I used Lime Green Solo which will go over most surfaces and even plaster board without a primer. Old Lime plaster needs to be scratched first though. I must say my first attempt was pretty poor however, not entirely my fault I might add as the mixing instructions are clearly incorrect as confirmed later by online comments. Solo seems to get bad and good comments in equal measure. Ive decided to to get in a professional however. I'm just not confident that as a novice I can get a satisfactory finish. Im hoping to take on the role of apprentice for whoever I hire in the hope I can pick up a few tips and maybe try again when I start work downstairs!
  6.  
    Hi Kristeva,

    If you can start off with a flat substrate you could probably do a good job with the lightweight Baumit plasters. Effectively you are putting on a series of thin coats of equal-(ish) thickness (thin-ness), and each is a guide to the next. And the plaster is really 'forgiving'. I am not a plasterer and I get very good results.
    • CommentAuthorkristeva
    • CommentTimeSep 9th 2021
     
    Posted By: Nick ParsonsHi Kristeva,

    If you can start off with a flat substrate you could probably do a good job with the lightweight Baumit plasters. Effectively you are putting on a series of thin coats of equal-(ish) thickness (thin-ness), and each is a guide to the next. And the plaster is really 'forgiving'. I am not a plasterer and I get very good results.


    Thanks for the tip Nick, I was thinking of trying another product.

    I had a really flat surface to work with - a mix of old plaster and plaster board. My trouble stemmed from getting the right consistency of mix with Lime Green Solo. They stated in the instructions to add between 3 - 5 litres of water when in reality you need more like 6 -7 litres to get a consistency capable of a skim. I realised this half way through the job, applying the plaster was difficult and tiring, some patches too thick, others not thick enough. And of course as it was too dry it dried too fast which affected my timings. With Solo you go in 2 hours later with a sponge float to achieve the 'flat' finish, by the time i went in with my float it was already too hard to manoeuvre / manipulate the plaster. I decided to work the surface hard with the float in order to get it back down to something resembling flat so I could try again, or get someone else to.

    It seemed to me the main issue was my inability to apply the plaster with equal (ish) consistent thickness. I needed that initial coat to be much flatter in order to give me any chance of floating the wall flat later. Some of this was caused of course by the incorrect mix / consistency. First attempt I know but it knocked my confidence for sure, I was expecting it to be a bit better.

    Have you a link to these Baumit plasters, are there comprehensive instructions?
  8.  
    Kristeva, I have now plastered two difficult walls and feel like I am working my way through the list of 'mistakes to learn by' (mixing, consistency, timings, tools, you name it). But have the bit between my teeth now and not ready to give in quite yet. It is satisfying when it is going OK. I had some good success with using a speedskim for flattening... but then messed up with the timings for removing the ridges :bigsmile:
  9.  
    Kristeva and MV, hope to have some time Mon to put some thoughts together. I had a quick look and could not find any terribly useful instructions. I think most are in people's heads (and hands).
    • CommentAuthorArtiglio
    • CommentTimeSep 12th 2021
     
    I’ve tackled smallish areas of plastering using Baumit products, MC55 and RK70 as basecoats and KlimaGlatt as the finished surface.
    They are all relatively easy to use and for want of a better word stick easily to the surface you apply them to. Consistency is pretty much intuitive as you’ll soon work out what does and doesn’t work, just don’t make big mixes to start with. I had quite a bit of trouble with the Glatt to start with but found that misting the base surface with water made it much easier to work with. It takes me ages to sule the basecoats off but both 55 and 70 give plenty of working time and adding a fibreglass mesh again helps get a flat surface.
    Glatt goes on very thin and needs at least two coats ( for me anyway) and when i’ve made a hash of it , i llet it dry then sand it down and try again.
    Things improved markedly when i bought a refina 900mm flexible blade and a decent preworn finishing trowel. I can get a finish i’m happy with but it takes me an age. Despite the time needed to do so i’ll also fit battens to rule between then fill in gaps and corners etc.
    Plastering is one of those skills that takes lots of practice and effort to make it look easy, its all possible but in the absence of lots of said practice its a slow messy business and hard work.
    • CommentAuthorkristeva
    • CommentTimeSep 13th 2021
     
    Posted By: Nick ParsonsKristeva and MV, hope to have some time Mon to put some thoughts together. I had a quick look and could not find any terribly useful instructions. I think most are in people's heads (and hands).


    Thanks Nick



    Posted By: modernvictorianKristeva, I have now plastered two difficult walls and feel like I am working my way through the list of 'mistakes to learn by' (mixing, consistency, timings, tools, you name it). But have the bit between my teeth now and not ready to give in quite yet. It is satisfying when it is going OK. I had some good success with using a speedskim for flattening... but then messed up with the timings for removing the ridgeshttp:///newforum/extensions/Vanillacons/smilies/standard/bigsmile.gif" alt=":bigsmile:" title=":bigsmile:" >


    Thanks MV and Artiglio

    Well I returned to the house last week after my disappointment to look at the walls now dry and a few things struck me, firstly, although unacceptable in its current state, I quite like the look of an imperfect wall in my house. A super smooth, flat gypsum plastered wall just wouldn't fit. Secondly, I love the feel of the lime, like rock on the walls. I tap it with my knuckles and its rock hard, its not going anywhere.

    So although it was clearly a screw up and now even harder to fix / skim I decided to go again, reinvigorated by all the comments above. I concentrated on the small wall only this time and knocked up a much wetter, softer mix which was clearly easier to apply with much better results. I can trowel it much flatter. I skimmed the wall twice. Its all practice I guess, but I'm still struggling with the sponge float stage which doesn't seem to have the impact I was expecting. I suspect I'm still going in too late.
    • CommentAuthorkristeva
    • CommentTimeSep 13th 2021
     
    Posted By: modernvictorianKristeva, I have now plastered two difficult walls and feel like I am working my way through the list of 'mistakes to learn by' (mixing, consistency, timings, tools, you name it). But have the bit between my teeth now and not ready to give in quite yet. It is satisfying when it is going OK. I had some good success with using a speedskim for flattening... but then messed up with the timings for removing the ridgeshttp:///newforum/extensions/Vanillacons/smilies/standard/bigsmile.gif" alt=":bigsmile:" title=":bigsmile:" >


    MV, are you using LG Solo too?
    • CommentAuthorArtiglio
    • CommentTimeSep 14th 2021 edited
     
    Apologies, sule off is a typo i meant rule off.which to me is the act of flattening the applied base coat with a featheredge or long flexible blade

    https://ewistore.co.uk/shop/refina-spatula-rule/?gclid=EAIaIQobChMIid_-iPr98gIViOR3Ch0clAncEAQYBCABEgIKBPD_BwE

    Personally i don’t use a sponge float i found it invariablymade things worse in my hands. I use a pretty stiff cheap trowel for getting the base coats on and a larger 14” flexible pre worn trowel for the top coats. Something like this, the one i bought is much more flexible than the base coat trowel, the difference in use and finish is huge

    https://www.ffx.co.uk/product/Get/Marshalltown-Mpb14Ssd-0035965034333-Pre-Worn-Stainless-Steel-Plasterers-Trowel-14In



    No doubt a pro would be perplexed at how i go about things and would never be able to make a living at the pace i work at.

    The plasterers i was using won’t be coming back, their idea of an acceptable finish and “ straight/ smooth” wasn’t what i wanted, but they covered a latge number of metres inna day.

    Also if you are after a good finish a decent light is a real help.
  14.  
    Can I clarify that when I referred to a sponge I do not mean a sponge float? My sponge float would have made things worse, I think, but a fine, damp 'car washing' sponge is excellent, once the plaster is stiff enough not to 'drag', but not 'dry dry' (you see how objective all these measures are?!).

    You can still do the really fine 'Glatt' finish over the top. A bit strange to get used to - it goes on quite runny - a bit like thick cheese sauce (but does not taste as nice). You soon get used to it, though.

    If you find it hard to keep the plaster flat perhaps have a go using a toothed trowel and mesh, leave it to stiffen a bit, then go over. The toothed coat will give you a bit of a depth gauge, and the mesh will give some resistance to prevent you 'squeezing it down' unevenly. Try it on a small-ish 'test patch' (spare piece of plasterboard?) and keep building up till you feel confident.
    • CommentAuthorkristeva
    • CommentTimeSep 15th 2021
     
    Posted By: kristeva
    Posted By: modernvictorianKristeva, I have now plastered two difficult walls and feel like I am working my way through the list of 'mistakes to learn by' (mixing, consistency, timings, tools, you name it). But have the bit between my teeth now and not ready to give in quite yet. It is satisfying when it is going OK. I had some good success with using a speedskim for flattening... but then messed up with the timings for removing the ridgeshttp:///newforum/extensions/Vanillacons/smilies/standard/bigsmile.gif" alt="http:///newforum/extensions/Vanillacons/smilies/standard/bigsmile.gif" alt=":bigsmile:" title=":bigsmile:" >" title="http:///newforum/extensions/Vanillacons/smilies/standard/bigsmile.gif" alt=":bigsmile:" title=":bigsmile:" >" >


    MV, are you using LG Solo too?


    Sorry, scrap that! just read your original post again.
    • CommentAuthorkristeva
    • CommentTimeSep 15th 2021
     
    Posted By: Nick ParsonsCan I clarify that when I referred to a sponge I do not mean a sponge float? My sponge float would have made things worse, I think, but a fine, damp 'car washing' sponge is excellent, once the plaster is stiff enough not to 'drag', but not 'dry dry' (you see how objective all these measures are?!).

    You can still do the really fine 'Glatt' finish over the top. A bit strange to get used to - it goes on quite runny - a bit like thick cheese sauce (but does not taste as nice). You soon get used to it, though.

    If you find it hard to keep the plaster flat perhaps have a go using a toothed trowel and mesh, leave it to stiffen a bit, then go over. The toothed coat will give you a bit of a depth gauge, and the mesh will give some resistance to prevent you 'squeezing it down' unevenly. Try it on a small-ish 'test patch' (spare piece of plasterboard?) and keep building up till you feel confident.


    Thanks for the tips Nick. I forgot about the toothed trowel. I'm also going to buy a Car sponge and experiment with that. I'm convinced i'm going in to late anyway and probably being to 'light', after re-reading instructions I think I need to get vigorous at that stage. Its frustrating when you get the finish coat on really flat and think the sponge float will finish the job. And learning from your mistakes is messy and expensive lol.
    • CommentAuthorkristeva
    • CommentTimeSep 15th 2021 edited
     
    Posted By: ArtiglioApologies, sule off is a typo i meant rule off.which to me is the act of flattening the applied base coat with a featheredge or long flexible blade

    https://ewistore.co.uk/shop/refina-spatula-rule/?gclid=EAIaIQobChMIid_-iPr98gIViOR3Ch0clAncEAQYBCABEgIKBPD_BwE" rel="nofollow" >https://ewistore.co.uk/shop/refina-spatula-rule/?gclid=EAIaIQobChMIid_-iPr98gIViOR3Ch0clAncEAQYBCABEgIKBPD_BwE

    Personally i don’t use a sponge float i found it invariablymade things worse in my hands. I use a pretty stiff cheap trowel for getting the base coats on and a larger 14” flexible pre worn trowel for the top coats. Something like this, the one i bought is much more flexible than the base coat trowel, the difference in use and finish is huge

    https://www.ffx.co.uk/product/Get/Marshalltown-Mpb14Ssd-0035965034333-Pre-Worn-Stainless-Steel-Plasterers-Trowel-14In" rel="nofollow" >https://www.ffx.co.uk/product/Get/Marshalltown-Mpb14Ssd-0035965034333-Pre-Worn-Stainless-Steel-Plasterers-Trowel-14In



    No doubt a pro would be perplexed at how i go about things and would never be able to make a living at the pace i work at.

    The plasterers i was using won’t be coming back, their idea of an acceptable finish and “ straight/ smooth” wasn’t what i wanted, but they covered a latge number of metres inna day.

    Also if you are after a good finish a decent light is a real help.


    Ive decided I'm going to try going in with my flex-trowel much earlier than recommended and experiment with that, at the point the plaster isn't going to come off the also cut it with a straight edge.

    Im also get the idaa of applying battens as a rule guide intriguing although how to fill the gaps left behind effectively the same session.
  18.  
    Kristeva wrote:

    ''Thanks for the tips Nick. I forgot about the toothed trowel. I'm also going to buy a Car sponge and experiment with that. I'm convinced i'm going in to late anyway and probably being to 'light', after re-reading instructions I think I need to get vigorous at that stage.''

    Yes, vigorous is good unless you are too early, in which case you just ruin the plaster. Sod's Law frequently dictates that I am a bit late. Too, too late and you can do nothing. A little bit too late and, with a bit more water, you can really get your arm muscles into it and 'force the plaster into submission'.

    ''Its frustrating when you get the finish coat on really flat and think the sponge float will finish the job. And learning from your mistakes is messy and expensive lol.''

    Maybe that's a misunderstanding. I have never used, and would never use a sponge on the top coat. The sponging of the base-coat is, for me, to get the base coat as flat as, but grittier than, a top-coat (Grittier because the sponging brings up the aggregate). The Glatt finish is very thin and does not really 'build' (fill in imperfections). It just makes them shiny, so if you start with dints and scratches you will finish with shiny dints and scratches.

    I do hope that helps. *Don't sponge the top-coat*!! (Unless you want a grittier, 'rustic' finish, in which case just put on one more base coat as a 'top coat').
    • CommentAuthorArtiglio
    • CommentTimeSep 15th 2021
     
    Regarding the battens,

    I fit battens about 4’ apart , apply my base coat and rule off to the battens, once its flat remove the battens and fill the gaps using the wet plaster either side as a guide.Then apply the mesh and trowel it in, on what is by now a pretty flat base the act of trowel over the mesh or using the rule gets things nice and flat as its pressed into the plaster.

    As above Klima Glatt is very very fine and i was told to do it in two coats the first is a bit thicker in consistency and as described is basically the fill the surface of the base coat, the second thinner ( both in consistency and application)coat is the one that is polished up.

    I’m slowly getting a bit more confident , but i still need to do a bit of filling whilst decorating. I’m on the look out for a new professional plasterer as there’s just too much for me to do myself ( plus ceilings are a black art for me and take far too long), hopefully got a couple coming round to see if they want to do it. One seems quite keen to try out new products so maybe he’ll be up for it.
    • CommentAuthorjfb
    • CommentTimeSep 16th 2021
     
    Posted By: Nick ParsonsI have never used, and would never use a sponge on the top coat.


    I have used a sponge finish to good effect. I mean it tends to come in to its own when the render isn't super flat (where a normal float will work well) so will tend towards the rustic finish but it is a very forgiving way to finish the render that is a good get out clause for a beginner. Just don't overwet the sponge float.
  21.  
    Hi jfb. I think we may be agreeing, in that my reference to 'top coat' is specifically to the (thin and very smooth) Kalkin Glatt finish. My comment (''Unless you want a grittier, 'rustic' finish, in which case just put on one more base coat as a 'top coat' '') refers to rubbing up (with a sponge) another coat of the 'grittier' base-coat, instead of using the 'Glatt' at all.
  22.  
    Resurrecting this thread for a few more questions!

    I am trying to 'simplify' the system as far as possible so as not to scare my plasterer off. I have decided I need some help. I need to base coat and finish 1) walls covered in Bauwer Light insulating plaster, and 2) woodfibre boards. I am thinking to use Baumit base coat (RK38 or RK70) and finish (Klima Glatt) for both (just checking with the Bauwer guy that this is OK). I don't really like the Bauwer Finish they recommend as it is very sticky.

    Question is do I go for Baumit RK70 or 38 over the woodfibre? What is the main difference?
    • CommentAuthorArtiglio
    • CommentTimeNov 10th 2021
     
    If you call Baumit ask for the number of your regional rep, they’ll know chapter and verse on the various products.
  24.  
    Resurrecting for a second time :bigsmile:

    I still have a mix of a) bare brick walls, b) woodfibre pannelled walls, c) Bauwer light insulated walls.

    I have secured a willing plasterer (no mean feat) and planning to tell him to use the following:

    Baumit RK38 - base coat on brick
    Baumit RK70 - base coat on woodfibre (and also to replace the Bauer 'Finish' which is the mesh base layer).
    KlimaGlatt - finish coat over everything.

    Does this make sense?
  25.  
    Sorry MV, missed your Nov post!

    I have used RK70 over Bauer light and it seems fine.

    You've got the right things for the right uses there.

    If your plasterer is not already used to the Baumit products he/she will probably find:

    RK38 is as easy as Browning or Bonding.

    RK70 is straightforward but slow as previously discussed.

    Klima Glatt is just a bit strange to use. Not very like any Gypsum product in use. Doesn't 'build' much, so if you have imperfections in the RK70 you may just get shiny imperfections. It repays a bit of a 'play'!

    Good luck, and make sure you do a bit yourself now, so you are ready for next time.
    • CommentAuthorkristeva
    • CommentTimeMar 30th 2022 edited
     
    EDIT: forget my comments, just caught up with previous comments on thread.
  27.  
    Thanks Nick. I was hoping you would come by!

    I have done a couple of walls myself but need some help to really break the back of it. There will be a few more to do after as well I'm sure. Also the house is so full of plaster I can hardly move...
  28.  
    Next question (nothing is simple). The Bauwer light installation is now mostly complete but the plasterer has left the wood battens in the wall. I did not know he was planning to use battens so this was never discussed when quoting for the job. Anyhow, it is done now. I am wondering how much of an issue this is (thinking of possible expansion and contraction?). Should I cut them all out (involving going through a mesh layer of Bauwer Finish) or leave them be? I can see a slight ghosting in the Bauwer Finish layer which is how I know they are in there.
  29.  
    when we did a Hemcrete IWI we left the battens in place, stainless expamet over them, and then lime plaster over the top.
    Didn't seem to cause any problems for the year or so that we still owned it after it was done.
  30.  
    Back for an update on the Baumit plastering. I have been using the laser level instead of battens and although it sounds like overkill I have found it easier as it means I only have to worry about getting the walls nice and flat as I know they are already straight. So basically I project a beam at the desired thickness, dab on some plaster blobs in a vertical line, finish the dabs so that they just about touch the beam, wait for them to dry, fill between the dabs to make a vertical guide, wait for the lines to dry and then fill between the lines with RK38. Perfectly straight wall! I then did another a thinner backing coat which I ruled off with a speedskim (normal straight edge may have worked better) and then finished with a wet car sponge and one of those foam floats you can get in Wickes. Actually I mostly just used the float and some water as the plaster was really quite hard by this point. I was very pleasantly surprised at the quality of finish which could be achieved! Thanks Nick for all the tips. Next step Glatt...
      PHOTO-2023-05-31-16-46-01.jpg

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