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EPP Foam Availability

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Tosh McCaber04/08/2020 11:52:33
192 forum posts
24 photos

I've seen a spec for an American model showing 50mm EPP, density 1.9lb for the fuselage, and 1.3lb for the wings, all hot wire cut. I believe that most of the Chinese ready built foam models are constructed from, I think, EPP (Expanded Polypropylene?) foam. Please correct me if I'm wrong.

I know that Depron (Extruded Polystyrene) is available in up to 9mm thick sheets (the same B and Q equivalent). I wondered if there were any sources for thicker EPP boards.

Golly- just come across yet another foam- EPO??!  Used on an "Ahi" slope soarer by Hyperflight.

Any clarification on the foam types welcome!

Edited By Tosh McCaber on 04/08/2020 12:10:21

Edited By Tosh McCaber on 04/08/2020 12:17:11

Piers Bowlan04/08/2020 12:31:13
2168 forum posts
53 photos

Tosh, most foam models, whether from China or anywhere else, are usually made from Expended Polyolefin (EPO). It is much stronger than Expanded Polystyrene although slightly heavier. As far as I am aware it is not available in sheets, the models are moulded from it. Expanded Polypropylene is very tough but rather flexible and slightly rubbery so it is often reinforced with carbon fibre or glass strapping tape, as in the case of flying wings for instance. Car bumpers are often made with EPP incidentally. One of the drawbacks with EPP is getting a good finish on it although if lightweight filler is used and a laminating film covering, good results can be achieved as I found out recently.  EPP is also heavier than EPO (or EPS) but a model made of it is almost indestructible! Multiplex (MPX) models are made from their 'Elapor' foam but as far as I can tell this is EPO again, although I could stand corrected.

I have heard that sheets of EPP can be hard to source. I did buy some in the USA once but not tried to get any in the UK.


Edited By Piers Bowlan on 04/08/2020 12:43:37

Tosh McCaber04/08/2020 13:31:07
192 forum posts
24 photos

Thanks for that clarification, Piers.

For my simple mind, can you give the full names of the initials? Is the following correct?

EPO Expanded Polyolfin

EPS Expanded Polystyrene ?

EPP Expanded Polypropylene

I hope that's correct!

So, we're stuck with expanded plystyrene in sheets. I do have a sheet of blue Styrofoam in the loft. I wonder how it would compare in strength with the EPP or EPO expanded foams. I don't know whether there are any white colured equvalents of extruded polystyrene (Styrofoam) nowadays?

Denis Watkins04/08/2020 14:58:43
4633 forum posts
129 photos

Agree with Piers, as EPO is moulded, often as a complete airframe in dies.

EPP is hotwire cut to shape, and brilliant for indoor models, as it tends to bounce of walls without damage.

Bluefoam is heavy by comparison to most expanded foam and not great at resisting dings.

Depron is a great choice for building models, and the lightest material, easy to cut and glue, but will get dented and snap if provoked

Tosh McCaber04/08/2020 15:04:35
192 forum posts
24 photos

Hi Piers, Dennis, Thanks for the info. Am I correct with the initials?

Dennis, you mention EPP being hotwire cut. Can it be obtained in sheet form in the UK? Or were you referring to it in manufacturing trerms?


Piers Bowlan04/08/2020 15:32:25
2168 forum posts
53 photos

Yes the initials are correct. I think Polyolefin has an 'e' in it although spelling is not my strong point!

Phoenix Model Products used to produce a range of EPP models both powered and gliders but I believe they were discontinued when the EPP foam sheets became hard to source. Soar Ahead Sailplanes sell EPP flying wing kits made from EPP. You could try contacting Alan Head of SAS and ask him where he gets his from or alternatively ask him if you could buy some foam sheet from him.

EPP can be hotwire cut but the finish is not great and produces some pretty nasty fumes by all accounts.

As Denis says, buying some Depron foam is probably the easiest way to build a foam model. There have been some extremely impressive Depron model build blogs on this forum.

Edited By Piers Bowlan on 04/08/2020 15:33:57

Denis Watkins04/08/2020 15:36:44
4633 forum posts
129 photos

BRC Hobbies sell EPP sheet Tosh

Tosh McCaber04/08/2020 17:18:32
192 forum posts
24 photos

Thanks for that Dennis.

Strange site! Redirected to Robotbirds. Tried to phone, but unfortunately, they close at 4pm. I see that they have fairly short 600x450 sheets, in 5mm to 15mm thick. Not bad, but I wonder if there's anywhere that supplies sheets that are thicker (50mm min) sheets and larger (1m long)?

Taking your input, Piers maybe, I'll go for Depron, and laminate sheets for the fuselage- for the wings, can you use Depron as a skin, with a carbon or other spar at the high point of the chord?

Michael Barclay04/08/2020 18:01:41
145 forum posts
55 photos

Does anyone know if Graupner Vector Board is a form of EPP?

Bob Cotsford04/08/2020 18:53:20
8746 forum posts
489 photos

Try a Google search for EPP foam blocks, but I think most results will be large scale suppliers of foam for packing. Finding somewhere willing to sell one off blocks may involve a bit of legwork, or fingerwork, phoning around these packing material suppliers.

Good Luck!laugh

kevin b04/08/2020 18:56:39
1895 forum posts
150 photos

You could ask these people if they can supply in sheet form.


john davidson 104/08/2020 19:07:55
67 forum posts

Tosh you can skin depron with self adhesive vinyl from a sign shop, see Graham Dorschel on you tube on how to do it , it results in an immensely strong wing . £5 is enough for two 48 inch wings

regards John

Martin Dilly 104/08/2020 21:19:22
75 forum posts
17 photos

Just to add to the excitement, I believe XPS is extruded (as opposed to expanded) polystyrene. It's used, among other things, for the variable camber flaps on F1N indoor handlaunched gliders like this: Sold as Isover floor underlay.

Piers Bowlan05/08/2020 06:51:27
2168 forum posts
53 photos

This appears to be extruded styrofoam and pretty good value too, don't know what the weight is like though. Doesn't say what minimum quantities for delivery are.

Tosh McCaber05/08/2020 10:46:16
192 forum posts
24 photos

Thanks for all the info guys- so far so good. If I have any more info myself, I'll let you know.

Bob Cotsford05/08/2020 11:20:55
8746 forum posts
489 photos

Isn't Styrofoam just a brand name for an EPS sheet? I thought Tosh was after EPP?

Martin_K05/08/2020 11:56:59
194 forum posts
Posted by Bob Cotsford on 05/08/2020 11:20:55:

Isn't Styrofoam just a brand name for an EPS sheet?

Many years ago I bought something I am sure was described as Styrofoam (closed-cell extruded polystyrene, which I used to sculpt a model railway landscape) from Panel Systems.

Looking at their website today the thing I think I bought is now called Craftfoam and they carry a product Ravatherm XPS - formerly known as Styrofoam.

It looks like tradmarks and re-branding has confused matters.

Anyone using a supplier to the building trade had better want a large quantity!

Piers Bowlan05/08/2020 15:00:37
2168 forum posts
53 photos
Posted by Bob Cotsford on 05/08/2020 11:20:55:

Isn't Styrofoam just a brand name for an EPS sheet? I thought Tosh was after EPP?

I think this may clear up the confusion that exists sometimes. To paraphrase, Styrofoam is a closed cell blue foam made from extruded Polystyrene (XPS) and is a trade name, made by Dow Chemicals. Expanded Polystyrene, which is white, is sometimes incorrectly referred to as Styrofoam, notably in the US. Expanded Polystyrene is sold in sheets too in the building trade as Jablite.

I think Tosh is just researching foam generally Bob, as he is interested in Depron too.

Edited By Piers Bowlan on 05/08/2020 15:07:48

Tosh McCaber07/08/2020 13:39:36
192 forum posts
24 photos

Somebody mentioned that they thought that the flooring grade Floormate Styrofoam is too heavy. I've just found the specs- apparently it's 33Kg/cu.m. Does anyone know how that compares with the various other available foams?

Edited By Tosh McCaber on 07/08/2020 13:40:00

Denis Watkins07/08/2020 14:52:39
4633 forum posts
129 photos

Some quick numbers in my head for a 2 meter slope soarer cut from F!oormate, slab sided, cartoon scale.

Would weigh about 4lb without equipment or battery.

Have seen models this size weigh 1lb

Take another look at EPP or Depron

Edited By Denis Watkins on 07/08/2020 14:53:37

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