Plastering Waves.

[hoyboy]

Hi

I'm a novice plasterer - have just skimmed my 3rd wall. The walls had previously been plastered but it's in poor condition - skim was cracked, flakey and falling off. So I scraped off any loose plaster, PVA'd (5:1 night before, 3:1 shortly before putting on the mud) and re-skimmed.

My first wall was pretty dire due to lack of prep but the others are OK. That is to say, they look really smooth to the eye - even when you stick a halagon on them. However, when I run my hand up and down them I can detect a very slight wave in the plaster. Is this normal?

If not, how do you stop it?

I have a couple of floats (cheap B&Q and Marshalltown) and noticed a huge difference between them. Therefore, would be interested to know if there are better makes?

Also, out of interest - what are the plastic floats for? I did say I was a novice!?

James

 

[roughcaster]

So you're a novice plasterer,Awwwwh.That's ok,nothing wrong with that.Most of us (plasterers) have been one,at one time or another,and the rest have found proper jobs.Only kidding! ....I've read your post a few times and think that someone should reply to you.....I don't know what would cause the "waves" as you call them, in your plastered wall.Sounds to me it could be the way you put the plaster on the wall.Maybe,instead of spreading the plaster on from the bottom of the wall,up to the full stretch of your arm, giving you a thinner more even coat,you might be spreading it too thick over a shorter stretch,giving you a more uneven coat,and if you double up with the second coat in the same way,then you are bound to have "things" in your wall that you shouldn't have.Hard to say without seeing your method,but we all learn.Now... It's B&Q and Marshalltown "trowels",not floats.You will not get many plasterers who use the word "float"when refering to a plastering trowel.You asked if there were any better makes of trowel? There is probably no more famous brand than Marshalltown,although I have always used Tyzack and will continue to do so.It's a personal preference.Ragni is also a recommended brand. Plastic floats....These come in different sizes.You would probably never use one of these just skimming a wall or ceiling.When you progress to putting undercoat plaster or cement render onto bricks or blocks,then you would use a float once the coat of plaster/cement render was out to the required thickness and screeded off,you would use it to finish off the render, or to float off bonding/browning ready for finishing coats.They are also used for finishing concrete,wedding cakes, etc.There is much to learn.

Roughcaster.

 

[joe-90]

If you put a straight edge on most plastered walls (not plasterboard) you will find that they are usually all over the place. The general aim in plastering is to make the wall smooth - not dead flat like a billiard table.

If you want to get it dead flat then you'll need a darby or a straight edge.

 

[roughcaster]

Joe9o says,"If you put a straight-edge on MOST solid plastered walls,you will find that they are all over the place".He goes on to say,"The general aim in plastering is to make the wall smooth,not dead flat like a billiard table".So in other words, put it on as uneven as you want, as long as it's smooth,that's ok.I would not agree with that at all. The general aim of plastering a solid wall properly is to make it, as near as possible,smooth,flat,straight and plumb.There is no reason whatsoever for it to be any other way,unless the plaster is just put on free-hand with no levels or screeds to work from.That way,all the darby's and straight-edges in the world will not make a wall straight.Flat maybe,but never straight enough for say a worktop to fit against it,or a shower cubicle,shower trays,baths,skirting-boards, tiles,cupboards,coving, dado's,picture rails, etc etc, they would all show up if a wall wasn't straight.There is no such thing as a perfect wall we know,but joe90 must be talking about his own work being all over the place.You put your plaster on the way you want to joe,but for the past 40 years,i've done it the way that I was taught by tradesmen,the like of which you would go a long way to find nowadays.

Roughcaster.

 

[noseall]

but for the past 40 years,i've done it the way that I was taught by tradesmen,the like of which you would go a long way to find nowadays.

Roughcaster.

Here, here!

 

[hoyboy]

Tanks very much for the replies! Sorry - should have made myself clearer.. I'm a diy plasterer and learnt how with this website...

I put a flat edge against the wall and the 'waves' i'm talking about are under half a mm deep. You can feel them but not see em. Maybe I'm just being fussy as don't know what's normal....

However, your comments about the length of stroke are really useful. I'm sure I was doing it too short and looking forward to doing it a better way now.

I have another issue now anyway - not sure if I should start a new post?
Above where the picture rails used to be on my walls and all over the ceiling is a kinda gloss layer of paint which is really hard to remove - bits are loose and peeling but where they're not it's really tough. It seems to be painted directly onto the concrete walls. It looks like it would be far too glossy to plaster on - can you plaster on gloss? If not, any ideas how I can easily remove it?

phew... finished... I'll shut up now...

 

[joe-90]

Joe9o says,"If you put a straight-edge on MOST solid plastered walls,you will find that they are all over the place".He goes on to say,"The general aim in plastering is to make the wall smooth,not dead flat like a billiard table".So in other words, put it on as uneven as you want, as long as it's smooth,that's ok.I would not agree with that at all. The general aim of plastering a solid wall properly is to make it, as near as possible,smooth,flat,straight and plumb.There is no reason whatsoever for it to be any other way,unless the plaster is just put on free-hand with no levels or screeds to work from.That way,all the darby's and straight-edges in the world will not make a wall straight.Flat maybe,but never straight enough for say a worktop to fit against it,or a shower cubicle,shower trays,baths,skirting-boards, tiles,cupboards,coving, dado's,picture rails, etc etc, they would all show up if a wall wasn't straight.There is no such thing as a perfect wall we know,but joe90 must be talking about his own work being all over the place.You put your plaster on the way you want to joe,but for the past 40 years,i've done it the way that I was taught by tradesmen,the like of which you would go a long way to find nowadays.

Roughcaster.

Take a straight edge and spirit level on your travels and place it against a few walls.

Then come back and say it was buzzcocks.

 

[joe-90]

It looks like it would be far too glossy to plaster on - can you plaster on gloss? If not, any ideas how I can easily remove it?

phew... finished... I'll shut up now...

Coat it with neat PVA and skim when tacky.