Lime Skim advice please

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Lacan07
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Lime Skim advice please

Post by Lacan07 » Fri 16th Apr, 2021 9:22 am

Hi All

I'm in the middle of renovating a very old house that used form part of an early 1800's hop farm. I've been working on the upper floors and I'm now at the point where i need to skim the lime walls so my electrician can return to energise the upper circuit.

Whilst I've already lime plastered the bare brick wall under the stairs using Lime Green products (emergency due to electric meter relocation) I've decided to bring in a young plasterer to help me with the upstairs skim. He's new to Lime but keen to help. I've almost finished the prep work and we are currently at the planning stage and would appreciate any advice.

All walls have the original polished lime plaster but there was a bit of 'fall out' when removing the skirting board from the lath & plaster stud walls so I've had to replace some parts with plasterboard and the odd screw/washer to tighten the existing plaster back to lath. I've scrim taped all the joints and the joints between the plasterboard and existing lime plaster which I will prep/fill using a slightly thinner multi finish (gypsum).

But my main question is what type of lime to use and whether I should 'prep' the walls first with a thin mix of Lime putty and water (limewater) or just wet the walls to control suction?

What concoction for the skim?

1. A ready made product like St Astier Ecomortar R100, can be used on almost any surface but the most expensive option?

2. A ready mixed lime putty, just need to knock up?

3. Or should I make up my own using NHL 2 and fine sand, and if so what mix?

Apologies for all the questions, any experience from fellow forum members much appreciated.

Thanks. Paul

MatthewC
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Re: Lime Skim advice please

Post by MatthewC » Mon 19th Apr, 2021 5:31 pm

More than 10 years ago I found a young lad who said "I loved doing lime on my plastering course but I've done none since". So I provided the lime advice whilst he had the plastering expertise! However, to reduce the chance of error and take one variable out of the equation, I bought ready mixed mortar and plaster from Mike Wye. I am still very pleased with the result and don't consider the extra cost as a waste.

Full story at www.houseintheenchantedforest.blogspot.com.

Lacan07
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Re: Lime Skim advice please

Post by Lacan07 » Mon 19th Apr, 2021 9:28 pm

Thanks Matthew

That's a fair point and I kind of agree. Can you remember what type of plaster it was? What kind of finish did you get? I'm not expecting it to be anything like Multifinish and thats fine.

paulc
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Re: Lime Skim advice please

Post by paulc » Tue 20th Apr, 2021 10:20 am

For the plasterboarded sections, paint them with something like Febond Blue Grit and then slap lime plaster over the top - That is what I did with my kitchen ceiling, and it is holding up well.
For a thin skim coat, I'd either do a 2:1 fine marble & lime putty mix or use Mike Wye's Heritage plaster mix. If you want a more polished finish, then perhaps the Regency mix. Just wet the walls down with water (a 5l+ garden sprayer is handy) and then skim. Any polished area would benefit from a light sanding to give something for the skim coat to key to.

malcolm
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Re: Lime Skim advice please

Post by malcolm » Tue 20th Apr, 2021 5:39 pm

I used St Astier R50 untrafine in my snug for a 2 or 3mm skim. It was on top of a variety of surfaces and I wanted something to stick. It has stuck and seems breathable. They put something in to give it a fast chemical set which limits the time window for the plastic float and last spray that brings the lime to the surface to trowel to completely smooth. Mostly managed it but there are a couple of bits that might need a skim of filler.

When I've plastered from scratch I've used the normal lime, but the skim coat has tended to be applied over new lime so it can bond, and has been closer to 6mm thick. Working time is a lot better - you can throw your trowel at it then come back in the morning when you are in a better mood and finish it off.

I don't know how good a bond you would get lime putty mix to polished plaster that will have had something else on top in the past. But then I haven't tried it. Someone will have.

Lacan07
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Joined: Thu 15th Apr, 2021 5:11 pm

Re: Lime Skim advice please

Post by Lacan07 » Wed 21st Apr, 2021 7:55 pm

Thanks for all the replies, I've been advised to use Lime Green Solo by the Lime centre.

They also told me to scratch up the old lime surface and just wet it down. I'm going to use solo to fill the scrim instead of multi finish which just seemed like a faff.

I've noticed a few hairline cracks on the original surface, especially on the ceiling, should I scrim tape these too?

YorkshireCottage
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Re: Lime Skim advice please

Post by YorkshireCottage » Sat 24th Apr, 2021 7:20 pm

My lime plasterer used expletives when I mentioned Lime Green Solo after our builder suggested it. I would suggest contacting Tim at Eden Hotlime Mortars - he's very good and helpful. He'll be able to direct you.

Lacan07
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Re: Lime Skim advice please

Post by Lacan07 » Sat 24th Apr, 2021 8:38 pm

YorkshireCottage wrote:
Sat 24th Apr, 2021 7:20 pm
My lime plasterer used expletives when I mentioned Lime Green Solo after our builder suggested it. I would suggest contacting Tim at Eden Hotlime Mortars - he's very good and helpful. He'll be able to direct you.
Thanks. What was his problem with it? I've used it once before. Was it the final troweling?

MatthewC
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Re: Lime Skim advice please

Post by MatthewC » Sun 25th Apr, 2021 9:40 am

Lacan07 wrote:
Mon 19th Apr, 2021 9:28 pm
Thanks Matthew

That's a fair point and I kind of agree. Can you remember what type of plaster it was? What kind of finish did you get? I'm not expecting it to be anything like Multifinish and thats fine.
We used Mike Wye's normal plaster (2:1 fine sand:lime IIRC) for the first skim and then used their Regency plaster (really smooth!) for the top coat. I think you can get the normal stuff to a good finish with some work, but my chap seemed to find the Regency quite easy and I'm very happy with it. It's not far off a Multifinish surface with just a little character.
Lacan07 wrote:
Wed 21st Apr, 2021 7:55 pm
Thanks for all the replies, I've been advised to use Lime Green Solo by the Lime centre.

They also told me to scratch up the old lime surface and just wet it down. I'm going to use solo to fill the scrim instead of multi finish which just seemed like a faff.

I've noticed a few hairline cracks on the original surface, especially on the ceiling, should I scrim tape these too?
I used stuff called DG27 on top of old lime plaster and (I think) the Regency plaster went straight on top of that.

I wouldn't scrim the cracks - if you are worried get some "Lime Putty Filler" (as sold by Mike Wye, and others probably) - it is designed to fill those.

The full story should be somewhere in the 100+ posts on my blog http://houseintheenchantedforest.blogspot.com/

a twig
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Re: Lime Skim advice please

Post by a twig » Mon 26th Apr, 2021 8:23 pm

I’ve put this onto almost everything inside and out, gypsum, painted gypsum, old fat lime, wood wool boards etc

https://www.mikewye.co.uk/product/secil ... ta-cal-ac/

Was able to get a “normal” plasterer to get excellent results from it after watching a YouTube video and 10 mins with a knock up test mix to practice. Goes off quick enough to paint within a few days

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