Celotex and the like

[WIMorrison]

I am going to use a celotex equivalent for the base of the scenery as it is light, has good strength for the weight Andes easily sculpted however I cannot fathom an easy way to get the silver foils of the surface other than bit by tiny bit and that will take forever

 

Anybody done this before and how did you do it?

 

Thanks

 

Iain

[chris p bacon]

You should be able to pull at a corner and rip it off although it will put up a fight. 

 

I leave the foil on the side that I stick down, I use 'gripfill' or 'no more nails' for this. 

[justin1985]

I seem to remember a lot of people discussing using Celotex etc when the pink Knauf "Spaceboard" type stuff that they used to sell in B&Q etc got much harder to find. The pink and blue insulation boards don't seem to have foil, but the Celotex type stuff does.

 

There was a lot of talk of Celotex curling up if only one side of foil was removed. I'm not sure whether that means it's fine with both sides removed, or whether the foil should always be kept on?

 

I've never actually tried this myself, but I do have some offcuts of the stuff kicking around after insulating the garage door. Any experience of its long term stability without the foil?

[chris p bacon]

I've stuck 2 lots down on separate layouts, I left the foil on the bottom and used Gripfill (no nails) to stick it down, and removed the foil from the top and carved with a knife and surform. This was then covered in plaster bandage. 

No problems with either.

[justin1985]

I've stuck 2 lots down on separate layouts, I left the foil on the bottom and used Gripfill (no nails) to stick it down, and removed the foil from the top and carved with a knife and surform. This was then covered in plaster bandage. 

No problems with either.

Thanks Dave, good to hear it works in practice. Baseboard materials seem to be one of the topics where people shout from the hills about the "theory" without having tried it themselves!

[57xx]

I seem to remember a lot of people discussing using Celotex etc when the pink Knauf "Spaceboard" type stuff that they used to sell in B&Q etc got much harder to find. The pink and blue insulation boards don't seem to have foil, but the Celotex type stuff does.

There was a lot of talk of Celotex curling up if only one side of foil was removed. I'm not sure whether that means it's fine with both sides removed, or whether the foil should always be kept on?

I've never actually tried this myself, but I do have some offcuts of the stuff kicking around after insulating the garage door. Any experience of its long term stability without the foil?

Yes, it warps. I tried to use it as a baseboard for one of the Challenges.I took the foil off both sides and glued it to a some mdf om the bottom and back. After a year it was warped in two dimensions. Edited July 22, 2018 by 57xx

[Buhar]

I suspect that's an MDF issue rather than the Celotex deforming because the foil is off.

[sulzer27jd]

Celotex is actually quite unstable and will warp and twist over time. It is especially so if one face has the foil removed. Try to find the proper Knauf material, which I think is available (at least in the blue) from a supplier in England.

 

John

[chris p bacon]

Celotex is actually quite unstable and will warp and twist over time. It is especially so if one face has the foil removed. Try to find the proper Knauf material, which I think is available (at least in the blue) from a supplier in England.

 

John

 

 

I've been using it for years in both work and modelling and never had an issue with it 'warping',      thinking about it I've got a half sheet in the top of the container that's wedged with 2/3rds unsupported, and has been there for 12+ months and it's still flat as a pancake.

 

The Knauf (blue) is actually (technically) a different material to Celotex.

Edited July 23, 2018 by chris p bacon

[sulzer27jd]

I've been using it for years in both work and modelling and never had an issue with it 'warping',      thinking about it I've got a half sheet in the top of the container that's wedged with 2/3rds unsupported, and has been there for 12+ months and it's still flat as a pancake.

 

The Knauf (blue) is actually (technically) a different material to Celotex.

 

Of course, Celotex is actually a name for a range of products and they are entirely different from the 'styrofoam' sheets that are being discussed as blue sheet. I did a  number of experiments with Celotex to test its suitability as a possible baseboard  material (substituting for blue sheet) and it has warped beyond any reasonable use. It is usable for scenery but I find it a horrible material to work with.

[chris p bacon]

Of course, Celotex is actually a name for a range of products and they are entirely different from the 'styrofoam' sheets that are being discussed as blue sheet. I did a  number of experiments with Celotex to test its suitability as a possible baseboard  material (substituting for blue sheet) and it has warped beyond any reasonable use. It is usable for scenery but I find it a horrible material to work with.

 

 

I genuinely find that strange, the spec for 'Celotex' is that it must be stable, it is not always fixed in place as it is sometimes laid as a tray. What thickness were you using ? even 25mm stays flat.

 

http://www.insulation4less.co.uk/insulation-materials/floor-insulation/celotex/

 

 

Some time ago we had a sheet of 100mm which was between 2 trestles and the plasterer stood on it to show that it did have some strength, It barely showed any movement. I suggested he didn't jump up and down.

[justin1985]

I just Googled for suppliers of "blue" type styrofoam (really annoying that the DIY sheds don't seem to sell anything but Celotex now) and found this notice

 

 

 

There are significant changes underway in the supply of Styrofoam the market leading extruded polystyrene. During 2018 Dow Chemical will cease the manufacture of blue Styrofoam and replace with a new improved product called Xenergy Styrofoam. This product will be grey in colour and offer the same mechanical properties but will provide improved thermal performance. The process of winding down stocks of blue Styrofoam is already underway with some grades already exhausted such as RTM, these will be supplied in the new improved grade of Xenergy. Other grades will be phased in over coming months. 

https://www.panelsystems.co.uk/product/styrofoam

 

I guess the "same mechanical properties" means it still still be suitable for modelling. I hope anyway.

 

It seems like the Knauf Spaceboard Eco "pink" stuff is long gone - shame!

 

Justin

[AndrewC]

There have been several threads on this.

 

Basically the Knaupf and Celotex are moulded sheets of medium density. They are great for scenery and easier to shape but not suitable as a load bearing baseboard structure. The lower density material will warp over time and is not as stable as the much higher density blue extruded foam. Celotex gets much of its stability from the foil coating acting as a laminated ply structure. Remove the foil and it is weakened greatly.

 

I've built over 20 modular boards with foam as the structural base in the past 8 years. The Knaupf and Celotex warped and shrunk slightly. The Dow Floormate blue is still perfectly level with no visible shrinkage. After all it is designed to be used under flooring. I can and have walked on my modules. Peeled Celotex will leave a dent. Floormate won't.

 

Smaller sheets of the blue in varying thickness can be found at 4D models. Any larger amount and it is worth getting a pack of 5 sheets from Sheffield Insulations.

Edited July 25, 2018 by AndrewC

[Damo666]

Approaching this from my profession (Architecture, specifying materials 30+ years):

Celotex is, as has been noted, a brand name. They make many types of insulation, various thicknesses and finishes. No need to focus just on Celotex.

 

The type of insulation generally discussed here is a requirement for a rigid board.

 

Insulation boards are mainly defined by the type of foam used in its production.

Expanded Polystyrene (EPS) looks like lots of small beads. Generally NOT what you want. It is cheaper than the others, but creates a mess with lots of static charge & the beads sticking to everywhere. Will need filler. Although classed as a rigid board, will break easily.

Extruded Polystyrene (XPS). A lot denser than EPS. This is what I think you are looking for. Can be supplied with or without Foil. Foil-less are generally difficult to find, most boards are manufactured with foil facing.

Polyisocyanurate (Poluiso, PIR or ISO): More energy efficient than XPS, and generally more expensive. No advantage for modelling. Unless given free off-cuts from a building site, don't waste your money on this, or your time researching.

 

Manufacturers of XPS: (I think the colour is artificially added as a marketing brand)

Celotex (Blue)

Kingspan (Pink)

EcoTherm (Light beige colour)

Xtratherm

Quinn Insulation

 

With regard to removing the foil, I remember been told many years ago by our tutor that Plywood ALWAYS has to have an odd number of ply sheets, to counter balance the sides. If we were ever to specify a ply laminate finish to a board we must fix a counter ply to the rear face, otherwise it will bend or warp, no matter how much it is fixed down.

So the same would go with foil faced XPS. the foam will have a different coefficient of expansion than the foil and, unless both sides are the same, something will move.

 

So, my advice is:

Try any supplier of XPS without the foil facing. Xtratherm seem to have a few products available.

Sheffield Insulation (No connection) are a nationwide supplier of a whole range of insulation boards. I used them in a personal capacity years ago, got my wife to pick up the boards. Were very helpful as a 'Joe Public' customer. Should be able to offer advice and several options.

Avoid EPS

Colour is irrelevant, Celotex, Kingspan, Ecotherm

Insulation companies that don't make rigid insulation: Rockwool, Knauf (I was surprised at this, they must have dropped this from their range. Could have sworn they had Rigid insulation when they took the factory over from Pilkingtons)

Think Jablite only make EPS.

 

Hope this helps.

Edited July 25, 2018 by Damo666