Plaster skim

[swill453]

I'm about to try a bit of skimming to smooth out imperfections in a wall before decorating. I know it's best left to an expert, and I've never had brilliant results in the past.

But I'm fairly time-rich now, so thought I'd give it another go.

Does anyone have any good tips for an amateur, in terms of materials, tools or techniques?

Scott.

[DrFfybes]

There are loads of online videos - I suggest watching several.

I learnt 2 things...
1) the mix is wetter/softer than I thought it would be
2) when you think "that's nearly perfect, I'll just give that bit one more pass to get that slight ridge out" then stop IMMEDIATELY, BEFORE you give it one more pass - you can always rub it back a bit after it has set.

Paul

[Howard]

As a complete amateur, many years ago I watched and chatted to, a professional who plastered a wall in my house. He started with a creamy mix and put this on with a float. His technique was leisurely, leaving the slightly irregular first coat for a few minutes. He then flicked a small amount of water over the wall with a paintbrush (a bit like a Bishop blessing a congregation by flicking holy water over them). And with a wet float he did the first smoothing. This was repeated several times over around quarter of an hour as the plaster dried at normal room temperature as the house was heated.

Each time he smoothed the job he used more pressure and the float was flat to the wall. Then he said "I'll have the coffee you offered." Having drunk the coffee, which took at least twenty minutes the plaster had dried more. He then repeated the water flicking and smoothed the job with a completely flat trowel and quite hard pressure. This produced a lovely flat result and when fully dried it almost had a gloss sheen.

I couldn't resist buying a float and, over the years and many diy decorating jobs, have used his method. The results have always been presentable and approved by the casual observer (Mrs H) when I have then painted over them with a matt emulsion using a roller.

This technique also works well when filling cracks, I use a flat spatula tool rather than a full size float for this.

I'm sure other, more professional decorators, can suggest improvements to my technique, but as a fairly particular observer, my house walls would be in the top 10% for lack of imperfections. It took me a few years to improve the builder's finishes in my 20 year old house.

Hope this is helpful

Good luck with the decorating.

Howard

[Howard]

PS On Amazon the float I referred to is called a plastering trowel. Mine is a basic one costing around £5.

Link is;

https://www.amazon.co.uk/Draper-Redline ... ters+float

[supremetwo]

His technique was leisurely, leaving the slightly irregular first coat for a few minutes. He then flicked a small amount of water over the wall with a paintbrush (a bit like a Bishop blessing a congregation by flicking holy water over them). And with a wet float he did the first smoothing. This was repeated several times over around quarter of an hour as the plaster dried at normal room temperature as the house was heated.Howard

I observed our plasterer doing this with a paint brush.

I fetched one of the small pump-up adjustable water sprays used in the greenhouse and said "Try this".

He was over the moon with it.

[bungeejumper]

I can plaster up to about one square metre dead flat - enough, say, to cover a removed fireplace - but beyond that my reliability tends to wander a bit. I suppose I just don't have the professional eye for it.

I am, however, grateful to the kitchen fitter who first put me on to Artex Easifix. It stays workable for longer than conventional plaster, and for a couple of hours after it has set you can actually give it a coarse sanding (stop sniggering at the back, professionals ) - it then goes properly hard. It's called one-coat but you don't have to do it that way, obviously.

(NB: Do not employ the old plasterer's trick of adding Fairy Liquid to your plaster mix. It extends the period of plasticity, but the plaster will always lack strength.)

The other thing I usually keep handy is a metre long steel rule, which double-checks my own dodgy eye and which can help quite a lot with smoothing the plaster when you first put it up. (Any dead-true metal length would do.) Armed with these rudimentary cheats, I made a pretty damn good smooth repair on a Victorian lath-and-plaster ceiling where a sizeable plate of horse-hair plaster had lost its key and dropped about an inch. (Yes, I had to jack it and screw-and-glue it back up first, but there was still about a square foot of hole that I had to fill from scratch.) My final skim (about 1.5 sq metre) was just cosmetic finickiness, rather like the OP's by the sound of it, but it was very effective. Why, even the memsahib approved.

BJ

[sg31]

I'm a builder and have done a lot of plastering although it wasn't my trade particularly.

What is the existing finish of the wall?

Is it relatively even?

Once I know this I can tell you how to prepare the wall for plastering. To get a good result you need to do the right preparation.

Is it a full wall or just a section you want to plaster and blend in with the existing?

[swill453]

What is the existing finish of the wall?

Is it relatively even?

We've stripped wallpaper from the wall. In some areas (up to 50cm X 50cm) the paper surface of the underlying plasterboard is exposed, the rest is painted and probably smooth enough.

Would prefer to only skim individual imperfections, but prepared to do whole walls if that's the only way of getting it acceptably smooth.

Scott.

[sg31]

Thanks for the reply.

Whether you do patches or the whole wall will depend on how big the whole wall is and how adventurous you feel. If it's only one or two small patches you might be best just doing those if it's more extensive do the whole wall. (or get a plasterer in)

You've got 2 choices, if you are just doing patches then you can get 2.5L tubs of repair plaster from B&Q or the other DIY sheds, I've never used them so can only give general advice, if you are doing the whole wall you will need a bag of multi finish plaster* from a builders merchant and detailed instructions. I can give you those but you will also need a tub of PVA, a hawk, trowel, gauging trowel, a deep bucket and a piece of ply wood or similar to use as a spot board.

Have a think about it and let me know whether it's patches or the whole wall and we can take it from there.

* you could use a board finish plaster but multi finish is more forgiving.

[swill453]

Just patches then

Scott.

[JessUK98]

Some great tips here, thanks. I have several patches I need to skim over, including one large section under the dining room window. Was thinking about giving it a crack myself as I've inherited a lot of my dads tools. My house is pre 1820s and not even remotely straight or even anywhere so I doubt my amateur attempts would be noticable
Unfortunately the walls have blown pink gypsum, rather than lime plaster. For patching up I might just use something similar again and in the future get a pro in to lime plaster all the external facing walls properly.

[sg31]

OK.

Your defects are only about 3mm deep* so buy one of the ready mixed plasters from a DIY shed. I've not used them so just read the tubs and see which is best for your purpose. You will also need something like a gauging trowel and a plastering trowel. a hawk helps but isn't necessary for small holes

Clean the patches to be repaired so there's no loose bits and clear about a 1' and around the patch of all wallpaper residue. It's a good idea to paint the patch with PVA adhesive in a 1 to 3 ratio with water. 1 PVA/3 water. This stops the dry wall sucking all the moisture out of the plaster. Some of the ready mixed plasters probably have an additive to reduce the suck but I'd still be tempted to do this because it stabilises any loose bits. Let the PVA dry.
If the patches are small enough to span with the trowel you are in luck just fill the patches with plaster using the gauging trowel or plastering trowel then put the plastering trowel either side if the patch so it rests on the good plaster and holding it at about 30degrees to the wall slowly draw it across the wet plaster. In effect this will leave it almost flush with the surrounding wall level. You might want to do it a few times until it's the best you can get.

The tub will tell you what to do next but generally you then need to leave it to go harder. Sort of rubbery rather than rock hard. If you go over it again at this stage you should be able to scrape off any high bits and use the scrapings to fill any low bits. If you are then satisfied it's job done but you might want to wait for it to harden some more and have another go. If it's quite hard splash a bit of water on it which will make it more workable.

When you've done don't worry if it's not perfect, you can use a bit of sand paper and filler.

If the holes are bigger than the trowel use a straight piece of wood to scrape across the patch to get the initial level, then use the plastering trowel when the plaster is harder.

*I hope that helps. If there's anything you aren't sure about let me know.

*Deep holes that need filling are different to the above

[stewamax]

A plasterer who worked for a large contractor and who doing some work in my house once told me of a job he did elsewhere. The air in the latter house was very humid (other plaster drying out perhaps) and his end result was a perfect gloss finish. He was later taken to task by one of the decorators who complained that the surface was so glossy his wallpaper wouldn't stick!

[sg31]

A plasterer who worked for a large contractor and who doing some work in my house once told me of a job he did elsewhere. The air in the latter house was very humid (other plaster drying out perhaps) and his end result was a perfect gloss finish. He was later taken to task by one of the decorators who complained that the surface was so glossy his wallpaper wouldn't stick!

I've never been a fan of a high polished finish for the reason given. It's a good job really for 2 reasons, it takes more work and as a general builder I'm a decent plasterer rather than a very good one.

[88V8]

..... a perfect gloss finish. He was later taken to task by one of the decorators who complained that the surface was so glossy his wallpaper wouldn't stick!

And nor will paint. As evidenced in a room I'm repairing. 25 years of paint can be peeled off back to the plaster.

As an alternative to a ready mix, Universal One Coat. https://www.british-gypsum.com/products ... oat?tab0=0
Large and small bags.

V8

[sg31]

..... a perfect gloss finish. He was later taken to task by one of the decorators who complained that the surface was so glossy his wallpaper wouldn't stick!

And nor will paint. As evidenced in a room I'm repairing. 25 years of paint can be peeled off back to the plaster.

As an alternative to a ready mix, Universal One Coat. https://www.british-gypsum.com/products ... oat?tab0=0
Large and small bags.

V8

One Coat would be cheaper but I didn't recommend it because getting the consistency of mix just right would have added another complication. It's also a bit gritty for a good finish. I'd definitely recommend it for deeper holes like chases for electrics and plumbing where you want to get the job done quickly.

It's quite difficult explaining plastering a whole wall in a post which is why I was glad we were only dealing with small holes in this case. A friend once asked me to write him instructions on how to re-plaster a wall and email it to him. I tried but there are so many variables it would have taken an age and you can be sure he would have missed something important. In the end I went round and held his hand while he did it himself.

How do you explain about when the first coat is just right to put the second coat over it? Dead easy to let someone feel it, after that they just know.

[JessUK98]

I've had a crack at this plastering lark. I've skimmed a few large sections and patched up a few holes. The larger sections were quite difficult to get a nice finish on, and it took a while to get the hang of it. I'd hate to do an entire wall, let alone a whole room. I'm quite pleased with the results as it doesn't look any worse that the rest of the plaster in the room now
I'm in awe of plasterers that can get a flawless finish, especially on ceilings. Glad I've tried it, but will leave it to the pros to do if I want anything bigger done.