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Thread: Adventures in BLUE STUFF

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    Add a little water to the milliput , that helps it squish into the detail better ,I use milliput A LOT!have pretty much all the varieties.

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    FWIW, a procedure used in full-size boats and airplanes, and their models, is to "paint" the inside of the mold with a more fluid epoxy resin, called a gel coat, first.

    Then,when the gel coat has had some time to cure, back it up with the stouter stuff.

    A suitable resin: https://www.scalehobbyist.com/catago...FQwYgQodZTIB9Q
    or similar.

    The R/C model aircraft folks (a group that used to include me) do a lot of this kind of thing, usually with fiberglass cloth and more resin to back up the gel coat.
    Bob Craig
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    Thanks, going back to the tutorial I watched I saw the guy kept making his hands wet when using it. I missed doing that. If anything the powder on my gloves dried things up.

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    If you should ever want to cast something that looks like concrete like a bridge pier, vibrate the mold during or after the pour - the bubbles come right up. Orbital sander more than does the job.

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    @baronjutter I have a question and a mention. The question is did you ever try a re cast with liquid or a finer putty? The mention was about a resin other than plast-aid which I referred to previously. I noticed Hobby Lobby sells a resin kit for $30 which has 3-5 times the volume of the plast-aid and would be fine for molding, presumably. With a 40% coupon would be $18 for those in the states. I guess you don't have Hobby Lobby in Canada but you might still be able to order it. Also, I'm sure other retailers sell it online. I believe the brand I looked at was Alumilite. Have you tried casting other parts? I know you have been busy with the tram.
    Daniel Dawson

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    I put the blue stuff away after a couple more failed attempts at casting. I guess my problem is that I don't really have anything to cast that I really need. I should have ordered that package of k-barriers last time I ordered some stuff, that would have been perfect because plaster comes out looking like concrete. The things I want to cast tend to be metal, containers, AC units and roof junk, which are very unforgiving as you expect sharp corners and smooth sides. I used to do quite a bit of casting with smooth-on stuff, cast some DPM and Lunde stuff. Was a lot of work and was pretty hit and miss.

    The videos I see have people using blue-stuff to reproduce detailed warhammer and other gaming figures and equipment, so it obviously can be done. Right now I just have other things to focus on, and the blue stuff was cheap enough that I'm fine shelving it for a long while. I certainly got some entertainment out of boiling and handling it!

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    When I was experimenting with resin casting, I made silicon and latex molds. Despite being very different materials, the info I read suggested using a release spray to coat the molds to make them last longer and ease removal.

    The other big bit of information was to match the molding material to the thing being created. The more surface detail or more delicate the molding the more waterlike/thinner the stuff should be. That's why most molding is done with liquid resins. Pastes and semi solids work best for thin castings with simple details. Many molding defects are caused by air. Either trapped in the molding compound or between the surface of the mold and material.

    With the putty, you need to be able to push it into every crevice and that is tough in a 3D object with intricate details. It is better suited to flat objects like railcar doors and ends. If you sliced up multiple containers, to make six clean sides, you'd be able to produce cleaner moldings. Then glueing the sides together will make a container. But you could just mold the long side and use it as a texture for a wall of them. Full containers on the ends and top of the long wall would hide the flat fakes. Like wrapping a chunk of wood to represent bundles of plywood.

    You could easily bash together a single K Barrier and mold more yourself. Staircases and simple one sided architectural details work best when using the putty. For more complicated stuff use a waterlike casting material. I had great results with Alumalite, that clear casting resin that is also used for water, drew air like an industrial vacuum cleaner. The surface never cured.
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    I got my Blue Stuff in the mail a while ago. Have not had time to play with it but wanted to point out that, much like many n-scale items, it is smaller / less than you might expect from the pictures. Plenty to make many / most n-scale molds but probably not enough to make a bunch of molds and leave them around to re-use later. It is re-usable so this may not be a big deal but just wanted to point this out.

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    Yeah it's about just enough to cast an N scale container or a single table top gaming figure.

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    Is that stuff re-usable? Or is it a permanent shape once it's heated the first time?

    Also about the air bubbles...vibration is the answer. Put the mold of something that vibrates while it's drying. Things like a bench grinder (just sit the mold next to it on a work bench if the whole bench vibrates), vacuum cleaner, fish tank air pump, floor speaker with the volume turned up....lots of stuff in any normal house vibrates. The vibration will shake the mix enough to allow the air bubbles to escape.

    This only works on liquids. Things like wet plaster, pourable plastics that harden, epoxies, stuff like that. It wont' work on clays and putties and stuff that bubbles will never have the buoyancy to push out of

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    Quote Originally Posted by Skipjacks View Post
    Is that stuff re-usable? Or is it a permanent shape once it's heated the first time?
    You can reuse it -- simply put in hot water again and re-use.

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    Sorry double post...
    Attached Images Attached Images

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    One application that was shared early on in this thread was making containers. I recently purchased 10x 48' smooth-side containers from Savonart on Ebay. For $10 + a few dollars shipping this is probably a viable option instead of trying to cast your own. I attached a couple of pictures side-by-side w/ manufactured units so you can see the quality of both the smooth-side and corrugated containers (they sent me the wrong ones first) from this supplier. There are some issues -- little bit of warping / bulging on some units and some small flaws here and there. But probably better or about the same as we would get on our own doing resin molds.

    20170130_202101.jpg 20170130_202141.jpg

    Tried to play with brightness / contrast so you can see more detail -- there are little rivets on the smooth-side containers but they don't really come out in the pictures.

    20170130_202101 (2).jpg 20170130_202136 (2).jpg

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    I finally had time to play with my Blue Stuff a bit and figured I would post the results here instead of creating a new thread. Also FYI -- I found out that this stuff is called Oyumaru and you can find more generic (i.e., cheaper) versions than the blue stuff. Here is a big lot of it -- http://www.ebay.com/itm/48-pcs-Oyuma...-/262773044951 and here is packages with 1.5 times what you get with Blue Stuff (for the same price you get about 3x) -- http://www.ebay.com/itm/Oyumaru-Reus...-/251271738205

    Anyway, my first experiments were not great but it seems promising. I need / want to mold a few different things.

    1) Trolley face -- this is basically a practice item for me (I got a kit with some missing pieces). I used Blue Stuff to mold and plumbers epoxy putty to test this first time. However, I have some liquid epoxy coming which I will also test since the part is pretty flat.
    2) MRC / Model 2-8-2 Power Smoke Box Cover -- most important and most complex item I would like to model (also worse results so far - even before I promptly cut the bell off my molded part). I tried a two part mold but first time put too much epoxy putty in and also did not press it into details enough (particularly headlight tube). Anyway, will keep trying to do this better (while avoiding breaking the bell of the original)
    3) Kato DD13 Battery Boxes -- a pair of DD13s I bought came with 1 of 4 of these boxes. This is a kinda complicated 3D shaped part and I will test with liquid epoxy but if that does not work I will need to model in pieces or scratch-build partly from styrene sheets.
    4) Stone walls -- for this I used blue stuff and air-dry clay (since consistency should be good for this and keeping cost down is a good thing / imperfections matter less). Anyway, not dry yet so you will need to wait for the reveal.

    20170601_221757.jpg

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    Ok I could not resist taking the air-dry clay wall out of its mold (although it say 2-3 days I figured this part was pretty thin). Came out perfect for my purposes. Seems like a no-brainer to use Blue Stuff and air-dry clay or similar (I'm going to experiment with Spackle next) for these types of features, to match an out-of-production tunnel portal you have, etc...

    20170602_071025.jpg
    Last edited by Mac; 2nd Jun 2017 at 10:44 AM.

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    I also made another attempt at the trolley face with less resin putty (I had made the part too thick the first time). Anyway, looking a bit better but I still need some practice (thankfully this is REALLY cheap to play with). It would have certainly been better to mold the original prior to building the trolley. Also I may need to better clean my mold and may want to remake the Blue Stuff Mold to see if issues I am seeing are with the mold vs. the resin. I still think the liquid resin will work a bit better for these flat parts but we will see.

    20170602_071423_001.jpg

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    As for the Smoke Box Front -- latest version came out a bit better. I need to see how easy it is to accurately trim the excess away. It is also looking like I may need to mold the headlight tube on the nose separately (unless the liquid resin does a good job filling it in). The back comes out great (which is of course the most important thing -- sarcasm). I may also need to mold the front and back separately if I use liquid resin.

    20170602_071539.jpg
    Attached Images Attached Images

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    Are you using any kind of mold release or lubricant?

    It looks like you just aren't getting rid of the air when making the mold or making the casting. You need to add vents.

    There is a basic rule of thumb when trying to cast something, the finer the details, the more like water your molding material has to be. Adding pressure and venting trapped air make a big difference. Using sludge where only water will go just will never give good results.

    Can you thin theBlue Stuff to the point you could paint it on? Perhaps try applying paper thin layers of the molding compound making sure you force it into every nook and cranny. The more you mimic liquid latex or RTV silicone the better your molds will be.
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    In order for the Blue Stuff to be soft enough for molding it needs to be put in hot water, maybe it needs to be hotter for it to take the detail better?
    Tim

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    Quote Originally Posted by ChicagoNW View Post
    Are you using any kind of mold release or lubricant?

    It looks like you just aren't getting rid of the air when making the mold or making the casting. You need to add vents.

    There is a basic rule of thumb when trying to cast something, the finer the details, the more like water your molding material has to be. Adding pressure and venting trapped air make a big difference. Using sludge where only water will go just will never give good results.

    Can you thin theBlue Stuff to the point you could paint it on? Perhaps try applying paper thin layers of the molding compound making sure you force it into every nook and cranny. The more you mimic liquid latex or RTV silicone the better your molds will be.
    Thanks --

    I am not using a mold release [yet] -- it seems to be releasing pretty well -- the only time I get some sticking is if the blue stuff made a plug when it came through the window on the trolley for example (it mushroomed inside the model). I may try to use something in the future.

    I agree for the loco nose I think the issue is air (but also the original is not a simple taper and has some details that might get messed up when I remove the original from the mold. I will try out the liquid resin with a vibrating something to shake out the bubbles and will also practice applying the clay resin in ways to avoid bubbles -- the first time I did the nose it came out terrible because I had a big bubble. The next time I did it in a couple of layers moving out from the middle to avoid this. I also need more practice and thinking creatively about how to use multi-part molds to avoid bubbles and get all the details without getting stuck on details.

    Not sure if the issue is the blue stuff mold or the resin... need to practice a bit more with both steps.

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