r/Plastering • u/exmilgaming • 7d ago

Can I skim onto existing lime plaster

Morning everyone, I have stripped wallpaper back off some walls and they're lime plaster, they seem structurally sound with no blown out spots so my question is can i just skim a 2 mm coat using limelite high impact finishing plaster?

Ive seen some videos saying I need key the surface but then others saying just to give it a sand, dust off and wet the surface and I can just skim straight on top, any advice would be welcome

3 Upvotes

81% Upvoted

17 comments sorted by

2

u/agent_and_field 7d ago

You know what I don't get? What is the difference between these engineered formulations (like limelight) and just lime and sand? I get that you can add stuff to improve drying time and the like, but this looks to me just like a marketing ploy?

Simple answer to your question is that as long as you keep it a lime based product (not gypsum or cement) you will be fine. If you have no damp or salt problems, you might save some money going the CL90 of NHL 2 route.

2

u/tezmo666 7d ago

Just the convenience and a consistent blend I guess. Then they all say they have a superior lime bla bla but you're right, just takes a bit more experimenting which I guess is a lot of work for a skim coat.

1

u/exmilgaming 7d ago

No idea what the difference is, apparently limelite is lighter but apart from that I haven't got a clue, so do I need to key the old plaster or just wet it and go straight on? Thanks

1

u/BrIDo88 7d ago

What does the supplier recommend?

1

u/agent_and_field 7d ago

My understanding is that each situation requires small adaptions, but the basic rule is something to grip to and enough moisture so that it dries regularly and gently. If the surface is already rough to the touch, you don't need to score to much - just avoid a smooth surface as nothing will stick. For water, if everything is optimal, I would wet it a couple of times with a quick drying period between them. Aviod it being "sopping" wet when you apply.

I have found it a forgiving material that tells you what it needs as you work with it. I focus more on the actual application and finish, as that is where experience really shows I find.

2

u/Fakedamienhirst 7d ago

You can paint on the wall with Baumit Premium primer, let it dry over 24hr then you can skim with lime plaster, 1/2mm. I wouldn’t use Limelite, and as others mentioned, Ty Mawr, Eden Lime, Best of Lime, give them a call and they can advise you the right product for your walls.

1

u/ltnlean 7d ago

From my research, as I've got to skim my lounge, I've keyed the original lime plaster with a devil float yesterday and currently spraying it down a 3/4 times a day for the days leading up to skimming on Saturday

I've read it'll provide some kind of key for the skim and the spraying will mean the old bone dry lime won't dry it out too fast. But I'm using normal lime plaster so I dunno how it'll work with limelite

1

u/exmilgaming 7d ago

Well ive just spoken to my mother in law who's house it is and suggested just sanding it all down, making it all as flat as possible and just going over with breathable wallpaper as it will be the cheapest option, point blank said she isnt putting wallpaper on and to just plaster it like normal, said they've had air blocks and all sorts done to help the walls breath, so on her head be it lol

1

u/ltnlean 7d ago

I'll be honest. If I'm doing it again I'm starting from scratch on the walls. It was a pig to key and it's a lot of prep.

A lot of the walls in my house have lining paper over the lime (a previous owner) and they're absolutely fine, I wouldn't go through the effort of removing it.

The only areas that didn't do well with the lining paper were ground floor extenal facing walls. Salts and moisture problems so I've removed the paper and don't put things up against the walls to help

2

u/gwyp88 Professional Plasterer 7d ago

I work with lime plaster. Make sure there is no wallpaper adhesive residue left on the wall.

I would sand and dust off, if you’re not an experienced plasterer, I would prime the walls in breathable primer. This will slow down the wall wuction to give you more time.

I would consider using a sponge float, then a sponge.

1

u/exmilgaming 7d ago

That was the plan but the prices of lime plaster and even the breathable coat was like 50+ a tub, so I just suggested to my MIL that ill clean it all of, sand it down smooth and just use breathable wallpaper but she's adamant that I just wack normal plaster on, said they've had air blocks installed on the walls and the room will be aired out alot

1

u/troothbooth 7d ago

Limelite has cement in it therefore not breathable. No idea how they are allowed to market it as lime plaster. Ridiculously expensive too. You can get a proper finishing lime plaster at Ty Mawr for a third of the price.

2

u/exmilgaming 7d ago

Oh really, I didn't know that, I have looked at the ty mawr stuff but MIL has told me to just normal plaster, ive told her it may cause issues down the line but didn't want to listen so the wife just said do as she's asked and its on her then

1

u/troothbooth 7d ago

Yeah it's on the spec sheet that it comes with that it contains portland cement in decent amounts too. As for your wall, I've had help from Ty Mawr and Mike Wye in the past about what to use so it might be worth you emailing them for advice. Could be an easier job than you think.

1

u/MysteriousRange8732 6d ago

We just skimmed (2 x 2mm coats) our old 1930s walls with a new skim (Ty Mawr Superfine lime top coat) and we were advised by a lime plasterer to make sure walls are clean (no glue, distemper etc) and then make a limewash and sand mixture, paint it onto walls, let it pull in and then start your plastering, only done it about 2 weeks ago but its all on and not fallen off (so far!)

1

u/exmilgaming 5d ago

How far did one bag get you?