How to seal XPS or EPS?

Discussion in 'Materials' started by MassimilianoPorta, Feb 17, 2020.

  1. ondarvr
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    ondarvr Senior Member

    The Duratec line of products can be tough to find in some parts of Europe, but they are around.

    Styroshield is their EPS compatible primer, it forms a barrier so any type of resin or coating can be used over it.

    It also sands easily, so it acts like a high build fairing compound if needed.

    XPS is a little different, many of the EPS compatible products don't work as well with it.
     
  2. MassimilianoPorta
    Joined: Apr 2019
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    MassimilianoPorta Junior Member

    You make me hungry! Send some over please :D
    Kidding apart, I will try to source it but I already know it will not be easy.

    In the meanwhile, what you think about epoxy with some glass?
     
  3. ondarvr
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    ondarvr Senior Member

    Thats the problem with EPS, its cheap and somewhat easy to shape, but so fragile it doesn't hold up to much abuse. By the time you compensate for the low physical properties and its vulnerability to resin and solvents, the cost and hassle factor goes up enough that other foams may become more attractive.

    For one-off shapes it still works well enough though.

    Some people do add a thin laminate to the surface, then do further shaping from there. The larger the part the more likely a structural layer is required.
     
  4. antonkov
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    antonkov Junior Member

  5. MassimilianoPorta
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    MassimilianoPorta Junior Member

    I totally agree with you.
    If I would have to factor the time (and material) spent on this plug, I could have bought 4 times the quantity of polyurethane foam!
    Problem is, again, it is not easy to source... even in the building shops, you find xps/eps no problem, but polyurethane almost never.
     
  6. MassimilianoPorta
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    MassimilianoPorta Junior Member

  7. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    We work with companies like that quite a bit, and the movie industry creating all those props.
     
  8. Rumars
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    Rumars Senior Member

  9. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    NYcell, these guys are in Italy. Not sure where I got the link from but I think someone said they give very competitive prices and aren't well known.
    nycell: pvc foam panel density 40 many thicknesses available http://www.pvc-core.com/en/category.html?Id=5

    EDIT: Oh it was actually linked by antonkov here.

    For structural applications PU might not be good either. I believe PU foam tends to crumble more easily under stress. Maybe someone can explain the physical properties of XPS and PU vs structural foams better.
     
  10. antonkov
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    antonkov Junior Member

    it has been a while since I looked into that foam. the deal there was that it is the same physical foam as what Diab sells as Divinicell but cut out of production ends or such and marketed as NYcell, it is a better deal if doing minor repairs, but for a big project I didn't want to risk with it. It seems like there is only one plant (in Italy) that makes crosslinked PVC and then the rest (e.g. Diab) cut/perforate it and brand on their exclusive markets. As of recently started to see crosslinked PVC coming from China, wonder if they make to foam or still cut and market it.

    I believe the original question was in the context of polystyrene as the cheapest option for a plug, which isn't very structural. PVC could be an overkill for this purpose also, it is hazardous and less easy to cut with a hot wire.
     
  11. antonkov
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    antonkov Junior Member

    off-topic, but on the subject of plugs... I started with EPS for my plugs, then switched to XPS, and then realized the 3D printer beats me in creating the shape. Now I print all compound surfaces and use developed foam board (from dollar store) for flats and unidimensional bends.

    20200421_191211.jpg 20200412_134838.jpg 20200404_202607.jpg 20200404_202522.jpg
     
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  12. Dejay
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    Dejay Senior Newbie

    Really nice 3D print! Definitely the way to go if you have a large enough 3D printer. Sorry didn't catch that it was for a plug.
     

  13. antonkov
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    antonkov Junior Member

    My printable volume is 30 x 30 x 32cm, printer itself was $300, material is $16/kg. The cost of plug surface formed by the printer comes comparable to the cost of XPS route considering the stiffening and barrier layers.
    Because the printer goes virtually 24/7 and I put only some 8hr/day, over the long run the printer wins :)

    20200404_230631.jpg 20200327_223806.jpg 20200225_222920.jpg
     
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