Striking off

GT Cornicer

New Member
I was wandering what people use when you strike off the cornice like a profile so that the cornice is consistent on the back? As will be easier to stand when drying and will know there are no weak spots when doing small boxing's. There was a guy from Essex who did that and my family all loved fitting his cornice so I want to do it the same. But don't want to scratch the plaster or fibreglass so if anyone does have any info it would be hugely appreciated!
 

superspread

Well-Known Member
I was wandering what people use when you strike off the cornice like a profile so that the cornice is consistent on the back? As will be easier to stand when drying and will know there are no weak spots when doing small boxing's. There was a guy from Essex who did that and my family all loved fitting his cornice so I want to do it the same. But don't want to scratch the plaster or fibreglass so if anyone does have any info it would be hugely appreciated!
A piece of lath
 

GT Cornicer

New Member
Sorry been hard at work then falling asleep. Here is a s**t drawing of what I mean. So I have the cornice being a consistent thickness throughout the length.
 

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GT Cornicer

New Member
I will do a drawing later that doesn't look like it was drawn by my 2 year old. And I don't see how a lath is going to make all that smooth on the back? Only the strike off areas, but it wouldn't do all of the back of the profile.
 

superspread

Well-Known Member
I will do a drawing later that doesn't look like it was drawn by my 2 year old. And I don't see how a lath is going to make all that smooth on the back? Only the strike off areas, but it wouldn't do all of the back of the profile.
Why do you need all the back of the profile smooth?only the strike off areas touch the wall and ceiling
 

GT Cornicer

New Member
This is what I mean as so many times cornice is too heavy in places and then weak in others so this is why I want to make it consistent on the back. Doesn't have to be smooth like the front but close to what ever I run over the back so that I know it's strong in all areas.
 

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superspread

Well-Known Member
This is what I mean as so many times cornice is too heavy in places and then weak in others so this is why I want to make it consistent on the back. Doesn't have to be smooth like the front but close to what ever I run over the back so that I know it's strong in all areas.
But that's why you splash (one of the reasons) to get an even thickness
 

GT Cornicer

New Member
But that's why you splash (one of the reasons) to get an even thickness
In theory,but I buy cornice from some good firm's and weak spots still appear. Don't need to do it for all cornices but Georgian and Victorian were made amazingly by this guy in Essex. So it's something I will do buy just want to know the best way and materials for doing so.
 

superspread

Well-Known Member
In theory,but I buy cornice from some good firm's and weak spots still appear. Don't need to do it for all cornices but Georgian and Victorian were made amazingly by this guy in Essex. So it's something I will do buy just want to know the best way and materials for doing so.
Use GRG , problem solved (y)
 

mikeadams1985

Private Member
what you mean is your use to fixing the cheap Chinese shite :D Thats all run off on the back.

Splash it and it will be fine, but if you did want to do it you need to cut another profile in say plastic that slides over the strike offs

like below...
 

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GT Cornicer

New Member
Definitely not the Chinese dog s**t. Ha. It's only for Georgians where you can keep the strength but also make it lighter by not having the bulk in the middle. Not for every cornice as that would be pointless. This is the firm that did it for certain cornices.

http://colesplastermouldings.co.uk
 

mikeadams1985

Private Member
What you want to do is stick some wads or laps as the southerners say across the back that will strengthen it right up. the georgian cornices do hinge across the thin points without it
 

mikeadams1985

Private Member
Jesus thats some thick cornice, no need for that sort of thickness
5-10mm thickness and reinforced with wads is plenty of strength
 

DaveCP

New Member
I'm currently experimenting with reverse moulds and have been shaping the backs using a profile rule made of 3mm ply shaped to the required back and sanded smooth - wooden version of the plastic one shown in mikeadams1985's post above. I hold it with a drag angle of about 30˚ and pull it over the length, positioned at its edges on the ruling-off surfaces.

The problem I'm having is being able to make the cornice thin without the back-profile rule snagging my scrim reinforcement.
 

ghurt

New Member
I was wandering what people use when you strike off the cornice like a profile so that the cornice is consistent on the back? As will be easier to stand when drying and will know there are no weak spots when doing small boxing's. There was a guy from Essex who did that and my family all loved fitting his cornice so I want to do it the same. But don't want to scratch the plaster or fibreglass so if anyone does have any info it would be hugely appreciated!
Cut a ply wood gauge.
 

The Hobo

Well-Known Member
I was wandering what people use when you strike off the cornice like a profile so that the cornice is consistent on the back? As will be easier to stand when drying and will know there are no weak spots when doing small boxing's. There was a guy from Essex who did that and my family all loved fitting his cornice so I want to do it the same. But don't want to scratch the plaster or fibreglass so if anyone does have any info it would be hugely appreciated!
I use the toe of a grouting trowel to srike off but for a constant thickness ijust do it by eye
 

puddove

Private Member
Did a job today where the cornice was made how I would like to do it. ( So no picture of volcanos)


the term fibrous plastering - refers to lightness and strength with fibers ( hessian / laths / sisal)

to thick- and the weight becomes the weakness
 
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