plaster taking ages to go off

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nashman680

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hi everyone
on monday i prepared a wall to plaster i put neat pva on the wall and left it till tuesday then i put another coat of watered down pva on when i put the skim on the wall it took an age to go off i have pva'd the other 3 walls on monday too and i am going back tomorrow to do the rest of the walls can i just put the plaster straight on the walls or do i have to add more pva
 
its concrete its an extension half the room was plastered and painted half of it was tiled when i took the tiles off i patched the holes up and now need to skim
 
can you be a bit more specific? when you say concrete i assume you mean poured reinforced corncrete.. as you wouldnt even attempt to put skim onto concrete blocks... in which case you wont have any suction, so pva wont help you, in fact it'll kill any slight suction there is, but then youve got no key??
but if you 'patched' holes, what did you patch them with? but then, neat pva over anything followed by another coat of wet pva is a) the wrong way round and b) just gonna cause you problems.... pva doesnt give a key, it reduces suction to manegable levels so the remaining suction gives a key...
multi is used on medium suction backgrounds (overskims etc), board finish is used on low suction backgrounds (board etc)...
 
p.v.a does give a key mate like an sbr slurry will outside, the tackiness sticks the skim to the wall otherwise youre just going over a shiny surface ;)
 
ill agree to differ on it if you will mate, no offence but thats what i used to think but a bit of research (anal stylie) and with some help from this forum this is my new approach to suction / adhesion..
normally adhesion is created by suction, the wall pulls the stuff in so it sticks... think overskim, board etc...
pva will kill excess suction so it doesnt 'burn' like skimming over old bonding without killing at least 'some' suction...
gloss paint... pva it and hit it with multi or even board, it gonna give you nightmares, slide all over the wall, etc.. try a sharpish round corner on gloss paint, pva'd or not...
silk paint... long as its well stuck to the wall, it'll still give you a little bit of suction, no pva, works ok...
pva it and the pva will run down the wall in streaks, hit it with plaster it'll give you problems...
gypbond it however, and hit it with board finish and the grit will stop it sliding, hold it to the wall and youll have ages to trowel it up but without the ripples you get without a key cos its moving as you trowel it...
silk paint that aint stuck.. your f'cked...
gloss paint without gypbond... your f'cked...
concrete, pva, dry, long as it doesnt slide you can trowel it up ok but has it actually stuck? pva lives up when it gets wet, thats why theres pva and 'waterproof' pva...
moisture resistant boards are recomended to use gypbond cos theres no suction, they dont recomend pva.. just read a bag of boardy...
i got my tips off gary b, put it to the test, and i find the guys bang on....
boardy for low suction, gypbond for no / very little suction and multi + pva for medium / high suction...
now thats just my mindset....
example though... my mate thought the same, pva over silk, let it go tacky, it'll give a key... f'ckin loads of problems this week for that exact reason, so i introduced a tub of wba i had on the van and a few bags of boardy...
first thing he says? ' no chance' didnt trust it or me, made a real small set, scared of it...
end of set whats he say? 'can you buy it in bigger tubs?'
i.ve always thought pva gives a 'key'...
now i think / 'know' its suction control only...
::)
 
i am skimming over previously skimmed walls i have patched up the holes with browning the previous plasterer has plastered the wall with a scratch coat then skimmed it
 
ill agree to differ on it if you will mate, no offence but thats what i used to think but a bit of research (anal stylie) and with some help from this forum this is my new approach to suction / adhesion..
normally adhesion is created by suction, the wall pulls the stuff in so it sticks... think overskim, board etc...
pva will kill excess suction so it doesnt 'burn' like skimming over old bonding without killing at least 'some' suction...
gloss paint... pva it and hit it with multi or even board, it gonna give you nightmares, slide all over the wall, etc.. try a  sharpish round corner on gloss paint, pva'd or not...
silk paint... long as its well stuck to the wall, it'll still give you a little bit of suction, no pva, works ok...
pva it and the pva will run down the wall in streaks, hit it with plaster it'll give you problems...
gypbond it however, and hit it with board finish and the grit will stop it sliding, hold it to the wall and youll have ages to trowel it up but without the ripples you get without a key cos its moving as you trowel it...
silk paint that aint stuck.. your f'cked...
gloss paint without gypbond... your f'cked...
concrete, pva, dry, long as it doesnt slide you can trowel it up ok but has it actually stuck? pva lives up when it gets wet, thats why theres pva and 'waterproof' pva...
moisture resistant boards are recomended to use gypbond cos theres no suction, they dont recomend pva.. just read a bag of boardy...
i got my tips off gary b, put it to the test, and i find the guys bang on....
boardy for low suction, gypbond for no / very little suction and multi + pva for medium / high suction...
now thats just my mindset....
example though... my mate thought the same, pva over silk, let it go tacky, it'll give a key... f'ckin loads of problems this week for that exact reason, so i introduced a tub of wba i had on the van and a few bags of boardy...
first thing he says? ' no chance' didnt trust it or me, made a real small set, scared of it...
end of set whats he say? 'can you buy it in bigger tubs?'
i.ve always thought pva gives a 'key'...
now i think / 'know' its suction control only...
::)
Click to expand...
i understand what youre saying mate suction does aid adhesion, no suction would result in very poor adhesion and in worse cases the plaster going off before its adhered ( like skimming gypbond before the gypbond has cured), but apart from overskims, newbuild work will always rely on a key thats why we devil float, plasterboard is designed for plaster i'll leave that one for the experts ::)
to be honest ive never skimmed straight over silk paint, it sounds ok in theory but killing suction is the easy bit all youre doing in practice is putting plaster which is going to set very brittle onto a smooth surface ..............it's a plasterers worse case scenario
you could be right mate i dont know but i would always skim over tacky pva if not using gypbond
 
thats just it mate, i no expert either but i think the idea of pva being tacky is so it ends up being mixed up with the plaster and bonds with the pva underneath it (which has bonded to the wall via suction, hence recommended 5:1 1st coat.. so it 'sucks' into the background, then 3:1 let it go tacky') but without suction to begin with the first coat of pva will just sit on the surface and go hard...
i understand thats the idea with gypbond, pva wont stick to a surface with no suction, it'll just harden over the top and all youll do applting plaster to tacky pva over no suction is stick your plaster to a skin of pva....
so a thick 1st coat of pva is a bad idea in my opinion, its like straight silk paint on new plaster, itll cover and dry lovely, but you can peel it off in big sheets... thats the idea of a mist coat with painting...
so im now a gypbond convert on the belief that gypbond will stick to gloss paint in the same way bonding will, then you stick the finsih plaster to that....
so in effect, a tight coat of bonding over a shiny painted surface will be almost as good as a coat of gypbond...
i think if matey got it on ok without too much trouble, no ripples, adverse effects apart from a longer setting time he should be ok, you can usually tell if you got problems cos areas of it start sliding about... then the heart sinks a bit...
these rooms this week, some of em had an old picture rail (2m off the deck), the lads on site pulled it out the wall and filled the gap with bonding (not hardwall)..
above was shiny as f'ck silk..
below was ex wallpaper over god knows what but it sucked like f'ck...
so we got silk at the top, followed by bonding, followed by real old plaster...what a bleedin nightmare to control and trowel up...
got away on the second room with near enough neat over the bonding, 2 coats over the lower section and sod all over the silk and hope it didnt bring the silk off the wall (which it did in places >:()...
then the gypbond came out... big smiles again :D
 
not necesarily mate, id just use board finish and as long as it doesnt slide all over the wall and a real pain to get a finish on you should be ok...
in fact, long as it isnt doing that, be thankfull your not running round like a blue arse fly!!
soon as it becomes a pain you know you got problems...
 
in fact just cos you put a thick pva coat on first, doesnt mean its sealed it and nothings gonna work or youd know, beleive me, its just not ideal.. i just wouldnt bother with a wet second coat...
 
;D youve completely sealed the walls mate thats why it's hanging around so much and if it's silky i wouldnt be surprised if it's sliding down the walls , but i'd still give it another coat as a key coat and if youre really struggling grind a coatof skimming into it while its tacky, let it pick up and then do youre two coats
 
yeh 3 coats will prolly get u out the sh't, once you got a coat on, if its pulled in at a reasonable rate you can assume its stuck reasonably well...
if the first coat hangs around, well, you cant be sure its stuck BUT if you let that pull in and give it another 2 youll get a finish on it ok...
end if the day ive never seen plaster falling off walls in big sheets, only ceilings ::)
 
i didnt have a problem getting it on the wall non at all it just i took ages to go off i was just wondering if i put another coat of pva on the wall would i have to same problem it took me 3 hours to do 1 small wall and i have another 3 to
 
Worst thing with pva is once its on it sometimes takes ages to go tacky, for instance if you're only skimming a ceiling and you have to hang about for a hour or more before you can skim it as you know it'll slide about if you're too impatient. Alot of times we've preped a room the night before, pva everything then just come in the next day and skimed it all. Works great, never had any problems and saves hanging about waiting for pva.
 
trick ive been using this week is if yo aint sure if the pva's gonna pull in or not...
wack the pva on, give it 10 minutes and if its hanging in little globules or streaks get a damp sponge and lightly wipe over it... it'll leave just a nice tacky surface to work on...
 
Good idea, we have thought about using a dry roller before but never seem to have one when its needed. Need to get one for the van.
 
PVA should NEVER be used neat, it forms a skin and can be peeled off, the weight of the plaster can pull the pva off in big sheets. You will find out when you give them a dry trowel....
 
hi all according to uni bond technical advise you should use only neat pva on painted and very low suctionsurfaces no sealer, i know this due to horrific problems with pva at beginning of year, couldn't get my head round it i've been using it nearly 20 yrs and my father also who was spread for 45 years, normally roller applied neat and skim straight over never had problems great finish. but this year there seemed something different it was seperating dragging even smelling different so rang gypsum who told me pva not recomended by them in conjunction with their plasters ok fair enough! so moved on to thistle bond it can only praise it found it fantastic you can prep it all out day one roller it on and skim it dry following day like a dream, its a bit pricey but got it down to 35 plus for 10litres, however have since found betakontakt made by knauf to be similarly good at same price for 20 litres. so tend to use that more have not used pva for overskim since, has anyone else experienced similar? not looking for lecture on using neat as tried allsorts of dilution with little success lol
 
hello mate where are you getting the betokontakt from and what prices ??
 
whats the setting time like with betokontakt mate is it like gypbondit ?
 
i do find different brands of pva can be vastly different in performance...
i use wickes a lot but it aint all that... i had some evo stick pva a while back and found it wicked stuff when i swapped over from wickes to evo on the same job..
f'ck knows, if i could get away with it id do like matey and gypbond every overskim...
nothin like noticing a wall start to go dull when youve only got bout 8-10 metres laid on... keeps yer fit!!
we really should keep quiet!! theyll be bunging the prices up next!!
 
dependant on background! i skim over a lightly scraped and roller applied artex ceiling in 2 hrs sometimes less its much quicker than bond it which they recommend 24hrs (you are talking about the green bond it?) hope that helps i use it neat on brickwork etc for patching and sealing its really good
 
yes mate bond it don't know why i call it gypbond.....................habbit i think :-/ .............where are you working spreadny ?........hows work mate are you doing site or domestic ?
 
We had major problems with pva this year too, like plaster sliding about the wall etc. Put it down to Evo bond changing the compound. Also We bought about 10 gallon tubs and think the frost had got to them in storage at the merchants. Have been thinking about bringing the pva in at night to stop the frost getting to it.We've normally got 2-3 tubs in the van at any time so don't want them knackered.
 
don,t laugh but i call myself artex2plaster textured surfaces made smooth all my mates took the piss out of my van but i've had loads a work off it do normal renovation and stuff but all domestic bang straight into the customer got a fair client base and get 10 weeks a year from a bathroom company. the vans just filled any gaps. got 6 weeks in front so fairly happy considering state of things. down in bath hows things for you you busy?
 
steady'ish mate i work for a local firm and from what i can gather were doing well at least were all still in a job :D ive put an add in the observer but ive not got any jobs ....charging 200 per day so im sure theres lads undercutting me at the mo
.........i know what you mean by artex to plaster 80 % of my domestic work is skimming artex ceilings ;)
 
it does what it says on the tin! thats canny advertising mate and its obviously working! starting a big renovation job next week (5 bed 3 ensuite, strip out and start again)) times no object so 2 of us are keeping it to ourselves from start to finish! should keep us going till after xmas.
 
went to price some artex overskims other day it was like crime scene due to insurance companies cottoning on to small amount of asbestos in pre 95 artex they had to have polythene seal full removal and airtest before was allowed through door so careful what your scraping lol good luck
 
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