Controlling Suction

P

Paul Sweeney

New Member
Hello All

I'm a proficient DIY plasterer and have generally achieved good results with the average smallish jobs for friends and family. I attended a plastering course (4 days) a while ago and had no problems so whilst not a Pro I am up to speed with the basics. I tackled both walls of a stairwell today (awkward) which had been cleared of wall paper and primed the day before with Plasterers Pre Grit. I was taken aback though by the ferrocity of the suction I encountered and had great difficulty in getting a decent spread as the Multifinish just leapt off the trowel and sat there 3 or 4 mmm right off the bat! I ended up on a rescue mission with a hell of a lot of cold water and three coats!

It was a cold day today and I had the front door open and upstairs windows open so I couldn't blame the heat. Any ideas as to why the suction was so fierce or what I could do to control it? There was no way I was going to do a traditional two coat application. We are talking two opposite walls approximately 8M2 each and British Gypsum Multifinish.

What can I do next time to avoid this? Thought the pre grit would have been enough?

Cheers,

Paul
 
Paul Sweeney said:
Hello All

I'm a proficient DIY plasterer and have generally achieved good results with the average smallish jobs for friends and family. I attended a plastering course (4 days) a while ago and had no problems so whilst not a Pro I am up to speed with the basics. I tackled both walls of a stairwell today (awkward) which had been cleared of wall paper and primed the day before with Plasterers Pre Grit. I was taken aback though by the ferrocity of the suction I encountered and had great difficulty in getting a decent spread as the Multifinish just leapt off the trowel and sat there 3 or 4 mmm right off the bat! I ended up on a rescue mission with a hell of a lot of cold water and three coats!

It was a cold day today and I had the front door open and upstairs windows open so I couldn't blame the heat. Any ideas as to why the suction was so fierce or what I could do to control it? There was no way I was going to do a traditional two coat application. We are talking two opposite walls approximately 8M2 each and British Gypsum Multifinish.

What can I do next time to avoid this? Thought the pre grit would have been enough?

Cheers,

Paul
Click to expand...
Ye mate, keep the window and doors shut for a start !
 
Paul Sweeney said:
Hello All

I'm a proficient DIY plasterer and have generally achieved good results with the average smallish jobs for friends and family. I attended a plastering course (4 days) a while ago and had no problems so whilst not a Pro I am up to speed with the basics. I tackled both walls of a stairwell today (awkward) which had been cleared of wall paper and primed the day before with Plasterers Pre Grit. I was taken aback though by the ferrocity of the suction I encountered and had great difficulty in getting a decent spread as the Multifinish just leapt off the trowel and sat there 3 or 4 mmm right off the bat! I ended up on a rescue mission with a hell of a lot of cold water and three coats!

It was a cold day today and I had the front door open and upstairs windows open so I couldn't blame the heat. Any ideas as to why the suction was so fierce or what I could do to control it? There was no way I was going to do a traditional two coat application. We are talking two opposite walls approximately 8M2 each and British Gypsum Multifinish.

What can I do next time to avoid this? Thought the pre grit would have been enough?

Cheers,

Paul
Click to expand...
We've all been caught out by suction at some point, but with proper training and experience you work your way through it. In your case we don't know the background you were skimming on to so can't comment on what would've been the best option.
A weak coat of PVA will generally tell you what the background suction is like. If it dries quickly it's high suction.
 
Thanks fellas I appreciate your inputs. To answer some questions: I used BondIt Plasterer's PreGrit applied a couple of days before. It was my brother's gaff and when I got there first thing he had the heating full on hence the windows. It's been a few years since I did my course but I don't recall being told to keep windows shut so thanks for that. I remember deing told to tackle ceilings first thing before the day warms up though.

I tackled one wall after finishing the other!

The walls were painted plaster with usual patch repair history after wallpaper had been removed. I might give SBR a go as I've got some of that. I do remember being told that the real reason to use PVA was to control suction not to provide adhesion so lesson learned on that. I thought the PreGrit was waterproof so hadn't expected such serious suction!

Anyway: you live and learn I appreciate the (helpfull) comments.

Cheers, Paul
 
BryanJ said:
They must only teach keeping windows and doors closed on a 5 day course? And controlling suction 6 day course?
Click to expand...
Will Ferrell Lol GIF
 
Suction control is really important when plastering, to much or to little causes issues. I’d guess that you didn’t apply the grit thick enough so it allowed the moisture to be pulled in. Another thing to make sure you mix it up well before you start and every 10 minutes or so to make sure the grit is going on the substrate and not sinking in the tub. Not enough grit and you’ve not got a mechanical key for the plaster to hold onto and can lead to the plaster delaminatin.
 
Paul Sweeney said:
Hello All

I'm a proficient DIY plasterer and have generally achieved good results with the average smallish jobs for friends and family. I attended a plastering course (4 days) a while ago and had no problems so whilst not a Pro I am up to speed with the basics. I tackled both walls of a stairwell today (awkward) which had been cleared of wall paper and primed the day before with Plasterers Pre Grit. I was taken aback though by the ferrocity of the suction I encountered and had great difficulty in getting a decent spread as the Multifinish just leapt off the trowel and sat there 3 or 4 mmm right off the bat! I ended up on a rescue mission with a hell of a lot of cold water and three coats!

It was a cold day today and I had the front door open and upstairs windows open so I couldn't blame the heat. Any ideas as to why the suction was so fierce or what I could do to control it? There was no way I was going to do a traditional two coat application. We are talking two opposite walls approximately 8M2 each and British Gypsum Multifinish.

What can I do next time to avoid this? Thought the pre grit would have been enough?

Cheers,

Paul
Click to expand...
Either you abused the pregrit in some way or you used out of date bags.

Used correctly it dries out into a rubber type finish and gives you a completely stable background to work on
 
All fresh bags from busy local builder's merchant. Maybe the PreGrit wasn't applied correctly as I left my bro to do that. I think paulf has made a very useful point. Apply weak PVA coat before starting job just to get the feel of what's going on before mixing up and spreading so no nasty surprises. Oh and shut the door and windows :)

Thanks everyone!
 
Paul Sweeney said:
All fresh bags from busy local builder's merchant. Maybe the PreGrit wasn't applied correctly as I left my bro to do that. I think paulf has made a very useful point. Apply weak PVA coat before starting job just to get the feel of what's going on before mixing up and spreading so no nasty surprises. Oh and shut the door and windows :)

Thanks everyone!
Click to expand...
@paulf never has anything useful to say
 
Paul Sweeney said:
All fresh bags from busy local builder's merchant. Maybe the PreGrit wasn't applied correctly as I left my bro to do that. I think paulf has made a very useful point. Apply weak PVA coat before starting job just to get the feel of what's going on before mixing up and spreading so no nasty surprises. Oh and shut the door and windows :)

Thanks everyone!
Click to expand...

Grit won’t get rid of suction, or not much. Suppose it depends on the brand. I tend to use green grit as it’s easily available, so on porous walls, I mix in a bit of SBR with it which stops it drying out too quick, helps it bond and kills the suction better.
 
ChrispyUK said:
Grit won’t get rid of suction, or not much. Suppose it depends on the brand. I tend to use green grit as it’s easily available, so on porous walls, I mix in a bit of SBR with it which stops it drying out too quick, helps it bond and kills the suction better.
Click to expand...
No it doesn't
 
Paul Sweeney said:
All fresh bags from busy local builder's merchant. Maybe the PreGrit wasn't applied correctly as I left my bro to do that. I think paulf has made a very useful point. Apply weak PVA coat before starting job just to get the feel of what's going on before mixing up and spreading so no nasty surprises. Oh and shut the door and windows :)

Thanks everyone!
Click to expand...

Grit won’t get rid of suction, or not much. Suppose it depends on the brand. I tend to use green grit as it’s easily available, so on porous walls, I mix in a bit of SBR with it which stops it drying out too quick, helps it bond and kills the suction better.
Stevieo said:
No it doesn't
Click to expand...

It does. It does!
 
ChrispyUK said:
Grit won’t get rid of suction, or not much. Suppose it depends on the brand. I tend to use green grit as it’s easily available, so on porous walls, I mix in a bit of SBR with it which stops it drying out too quick, helps it bond and kills the suction better.


It does. It does!
Click to expand...
Even though it specifically says not to do that on the tin.

Spack tard
 
You must log in or register to reply here.

Share this page

Back
Top