Bandai Kits vs. Mineral Spirits

Discussion in 'General Modeling' started by bcgd, Jun 4, 2016.

  1. bcgd

    bcgd Well-Known Member

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    This subject recently came up deep in the "Bandai Release Schedule: thread ( ) but I thought it was information worthy of it's own thread.

    I was wondering about this because during my recent Bandai TIE Fighter build ( ) I used odorless mineral spirits and oil paints for the weathering. I noticed later as I was doing touch-up that there was a crack in the hull. I thought it was kin of bizarre and the spirits were the only thing I could think of that could be the culprit. Fortunately it works with the whole Star Wars used look.


    Thanks Galactican for the helpful link!
  2. mash3d

    mash3d Active Member

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    I just put some Windsor & Newton white Spirits on part of the sprue from the Bandai AT-ST and a white sprue from the Storm Trooper kit.
    I also put some regular Klean Strip Turpentine on the same parts.
    I was going to let it set over night but it seems I didn't have to wait that long.

    The grey sprue from the AT-ST kit cracked with the Klean Strip Turpentine.
    But the Windsor & Newton white spirits didn't seem to have an effect on it.
    I don't have any odorless turpentine to check.
    The white plastic sprue from the Storm Trooper kit did not have any problems or cracking.

    Not sure if this affects any of the other colors of plastic that Bandai uses.
    Or if it's a combination of enamel paints and what ever paint thinner people may be using.
    I usually use acrylic paints.

  3. Galactican

    Galactican Well-Known Member

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    That might be it. Several AT-ST builders reported similar damages using oil paints. I guess there is something in the grey colour the kit is molded in because the main troubles are with the first models released in grey (the TIE and especially the AT-ST). The Stormie is molded in black and white colours and so far I haven't read anyone having trouble with him. I may remember that Bandai was looking into the problem and had changed the plastic to prevent this from happening on future releases. But I'm not sure about that. We better be careful and test the material we use on a piece of sprue first. A positive / negative list of the materials and their effects could be handy. :)
  4. beefkr10z

    beefkr10z New Member

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    I've used rubbing alcohol on Bandai Gundam kits to erase overspill on panel lines without issue for a long time, so this could be an alternative product to use- although I've never actually used it liberally on the models.
    Their newer panel lining markers (which are just thinned down paint/ink that use capillary action to run into grooves) also come with a GM300 eraser pen that smells like its alcohol based, but I can't translate the packaging to find out the composition- I know it's strong, though, as it took the gold colouring from my C-3PO kit down to silver in seconds, and after trying it on a spare sprue, it took the chrome right down to the bare plastic! Since this is an official Bandai product, it'd be safe to assume that this would be fine on all their plastics, but again, since I've only used it in small spots, I can't be sure.
  5. basementdweller

    basementdweller New Member

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    If you do a search on polystyrene and mineral spirits you will get the information you seek, I also posted it in that thread. All naptha (petroleum based) products will affect all types of styrene. How much the styrene is affected has more to do with the production method. Stress in the material is mainly caused by differential cooling and thicknesses (part design and mold flow) in the sprue, and logic dictates this will be exacerbated even further by mechanically stressed polystyrene like in snap fit joints. If the sprue has not been annealed by BanDai, then you will most likely get these fractures. Annealing in this context means reheating the plastic to below melting point in an oven and letting it cool uniformly in a slow fashion to get rid of some of the structural stress that differential cooling would have introduced during production.

    The book I got most of this from is called Injection Moulding Materials by A. Whelan, most relevant information around chapter 3.1 to 3.4. (I don't think I can link it properly, but you can find it with google and read the stuff).

    You should also check David Neat's great resource on the "Thinners and Solvents" page that also touches on this subject and lists all the type of thinners and their uses + effects on materials.

    Like mentioned in the post below (the power of edits), doing base coats in acrylic and sealing before applying oils and enamels and washes like that, will minimise the effects.
    Last edited: Jun 5, 2016
  6. astroboy

    astroboy Master Member RPF PREMIUM MEMBER

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    I have finished two x-wing kits (small and big) with no problems at all. I used primer, acrylics, flat top coat AND THEN oils with an odourless turpenoid. I had no problem.

    I also used the odourless turpenoid on a raw sprue from the ATST and still had no problems.

    I would say that if you want to use oils, make sure you have clear coats and use the lightest solvent that you can find
    Galactican and basementdweller like this.
  7. jinnai

    jinnai Member

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    Bandai plastic has been doing this for years and years and years. It's the main reason they abandoned trialing no polycap joints in gundam kits.

    The secret is to seal and glue. Ensure there's no bare plastic anywhere. Clear coats are your friend, but most Japanese modellers apply enamel washes directly over Mr. Color lacquers with no ill effects because they still glue.
  8. bcgd

    bcgd Well-Known Member

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    I sealed with Pledge but the mineral spirits were obviously too strong. Lesson learned for next time.
  9. Dedalus5550

    Dedalus5550 Sr Member RPF PREMIUM MEMBER

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    I've seen some of these threads but I feel lost. I did a few google searches for white spirits and mineral spirits and it seemed like these are terms modelers might throw around in a different way than the rest of the world. (We talk about "resin kits" but try looking up the word resin on the internet.) So here's my question. I mostly use MM enamels and sometimes I use MM/Testors thinner (from the big can) and sometimes I use lacquer thinner (from the even bigger can from Home Depot.) Does this method affect Bandai plastic? Most of my washes are simple water colors (the kind of children) because I get the look I like and there's never any danger of messing up the finish and it's real simple to start over and to mix wash colors on the fly. The wash I use, therefore, shouldn't be a problem, but what about my paint? Also, I sometimes use Tamiya paint from the jar with Mr. Thinner. Oh, and I use Future for gloss coats and MM Dull Coat.
    Mike Todd
  10. kamandi

    kamandi Active Member RPF PREMIUM MEMBER

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    I have experienced no problems with Weber Oderless Turpenoid while working on the Millennium Falcon. My primer coat was Mr. White Surfacer and a coat of Tamiya AS-20 Insignia White spray lacquer. I've done everything from fichtenfoo's millennium falcon videos and so far, so good. Now if only only I could find some "Starship Filth"...

  11. bcgd

    bcgd Well-Known Member

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    Per Helgan65 of eModels UK you can come close by mixing artist's oil colors Payne's Gray and Burnt Umber to the desired shade. I used a 50/50mix and it looked great!
  12. Gregatron

    Gregatron Well-Known Member

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    Yeah, I also use Testors Model Master enamels. I've been bitten by the bug, recently, and have a bunch of Bandai SW kits on their way to me. I'd rather not ruin them by painting them with enamels/thinner that will attack the plastic, but I'm also hesitant to invest the money and energy into a bunch of acrylic paints to substitute the enamel colors that I already have.
  13. kamandi

    kamandi Active Member RPF PREMIUM MEMBER

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    The best part about acrylics is if you screw up you drop your parts in a bucket of Simple Green for a day and it scrubs right off, every tiny nook and cranny. Enamels are not as cooperative.
  14. rbeach84

    rbeach84 Sr Member

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    Just shows, if in doubt, perform a "mad scientist" experiment first on scrap plastic & make sure your materials are compatible. Or simply build one copy as a "lab-rat" and see what happens... ;^P

    R/ Robert
  15. bcgd

    bcgd Well-Known Member

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    No doubt! I didn't know that it was a thing. I've watched a ton of weathering videos on YouTube and none of them even mentioned the possibility of it happening.
  16. mash3d

    mash3d Active Member

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    From what I can tell it was only the dark grey plastic used in the AT-ST model and maybe the Tie Fighter that had a problem.
    And it only happened when using really strong Turpentine out a large can from the hardware store.
    It did not happen when using the milder Artist white spirit from Windsor & Newton.

    If you want to be sure just run a test on the flat part of the Sprue where the label is.
    Primer it, paint it and weather it just like you normally would. Then push on it and see if it breaks.
    Also you may try applying a layer of clear coat like pledge floor care finish over the first paint layer.
    Let it dry overnight and then apply any decals then do the weathering. The clear coat will protect the first layer of paint and hopefully the plastic.

    The hairspray trick armor modelers use for weathering models may work also but I've never tried it with enamel paint.

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