Builder's Insulation Foam

[Andy Stephenson]

I'm having some alterations done to my house and the builders very kindly skipped some reasonable sized pieces of insulation foam, which didn't stay in there for long.

I'm guessing from the colour it's polyurethane.  I tried hot-wire cutting some and the finish is really smooth compared with EPS foam. Given what I hear about the fumes given off when cutting this stuff, I wore a carbon sprayer's mask. I worked out the density is 1.87Lb/Ft^3 which may be more than other foam types used for the hobby but it seems much stronger.

Has anyone else had experience of this material and what sort of finish/covering was used. I may try cutting some wings and applying a single layer of light-weight glass/epoxy.

Edited August 26, 2023 by Andy Stephenson

[martin collins 1]

I have used it to make moulds for canopies and just finished ir with a cew coays of PVA and paint before heating a pop bottle over it. Shoyld be great for scratch builds, foam decks etc. I plan to use it on a few of my builds using Deluxe materials glass cloth and Eze-Kote. 

[Eric Robson]

It's great material for working with,  I cut it with an old bread knife or coping saw. It sands to a good finish but easily dings. Once covered in brown paper it is light and strong, the nacelles on my foamboard 110 and Whirlwind are made with it. Covering with glass cloth would be better but after over 250 flights the 110 is still good 

[Andy Stephenson]

If this stuff isn't affected by solvents, I may even try doping on some tissue or nylon.

[Eric Robson]

I would keep solvents away from foam, I use pva just because it works, has low smell and is economical. I also only use it for electric models but there is no reason it can't be used for power planes as long as it is not exposed to petrol or nitro 

[Mike Chantler]

I found it difficult to hot wire compared with eps and  XPS, does it have something like glass fibre threads mixed in? And do you find that you need much higher temperature of hotwire cf eps?

[Andy Stephenson]

The temperature needs to be higher for the hot-wire and it seems to leave some ash behind. Nothing like glass threads in it but some foam when cut hot can leave wisps behind that look like glass.

[Ron Gray]

I found that the grey styrofoam blocks cut better and provided a much harder surface finish, the downside being that it is a lot harder to sand! 

[Mike Chantler]

5 hours ago, Andy Stephenson said:

The temperature needs to be higher for the hot-wire and it seems to leave some ash behind. Nothing like glass threads in it but some foam when cut hot can leave wisps behind that look like glass.

Thanks 🙂 - I maybe did not use enough juice

[PatMc]

Link to Safety Data sheet for Enertherm.

Looks like you would be best to wear a mask when sanding as well as HW cutting. 

[leccyflyer]

I've used it for it's intended purpose, insulating my lipo storage box, cutting very easily with a pruning saw. I assessed the surface and thought it was just too soft and weak for airframe use, since it dents so easily with just the mildest fingernail pressure. I'll be interested to see if others are able to make use of it for airframes.

[Andy Stephenson]

4 hours ago, PatMc said:

Link to Safety Data sheet for Enertherm.

Looks like you would be best to wear a mask when sanding as well as HW cutting. 

Any surface coating which may contain glass fibre is easily peeled off before use as a modelling material. This seems the only health hazard the safety data sheet is concerned with when working with the material, other than cutting dust which has an actual safe level which isn't zero. When hot-wire cutting, it would come under fire fighting measures, it seems strongly advisable to wear a chemical filter mask, which I do whatever foam I'm cutting, also with good ventilation if not outside.

[Piers Bowlan]

15 hours ago, Andy Stephenson said:

If this stuff isn't affected by solvents, I may even try doping on some tissue or nylon.

I have a feeling it is dissolved by dope or acetone. When glassing, epoxy resin/glass is OK  but polyester resin/glass will dissolve it.

I use brown paper and thinned PVA but add thin carbon fibre strips let into  the foam as spars. The brown paper shrinks slightly as it dries providing a good surface finish for painting. I cover both sides ( top and bottom) in one session to avoid warping.

[Nick Somerville]

Used insulation foam to shape the wing pylons on my P47. Lovely to sand (outdoors). Faced the flat area with balsa and covered in a couple of layers of light glass/epoxy. Have proved very durable.

 

 

[Andy Stephenson]

5 hours ago, Piers Bowlan said:

I have a feeling it is dissolved by dope or acetone. When glassing, epoxy resin/glass is OK  but polyester resin/glass will dissolve it.

I use brown paper and thinned PVA but add thin carbon fibre strips let into  the foam as spars. The brown paper shrinks slightly as it dries providing a good surface finish for painting. I cover both sides ( top and bottom) in one session to avoid warping.

The datasheet it says the core material is extruded polystyrene. As we know, this won't take solvents so epoxy/glass or water-based finishes it must be.

[Andy Stephenson]

Further investigation reveals that the particular material I have is polyisocyanurate foam which means to me that it's a derivative of polyurethane which I suspected in the first place. After having done various solvent tests such as cellulose thinners, cyno and nitro fuel none of which had any effect on the foam at all, this means it has more finishing options.

https://products.enertherm.eu/products/download/18/en/I