Using thermoplastic for broken and missing parts

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-bbbb

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I have a playmobil 4110 gondola which was missing a door, and one hinge for that door was broken off and missing the broken bits:
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I heard about thermoplastics for mold making.
So I bought some of this from Spain:


"Oyumaru" is a cheaper japanese alternative thermoplastic which comes in different colors, but I have not tested it. Both Oyumaru and Blue stuff can be reused over and over. Just put them in hot water again to make a new mold for something else. I'm not sure about Oyumaru, but Blue stuff doesn't require a mold release agent.

It was easy to make the molds of the door and hinge by warming the blue stuff in hot water for a few minutes and applying them to the good parts:

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I then used Milliput epoxy putty in the door mold and on the broken hinge with the mold of the good hinge:
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Milliput is easy to work with, but it's a bit brittle when cured/dried. in the next picture, you can see that the bit of the door which catches the door latch broke off as I removed it from the mold. "Green stuff" or "Procreate putty" might have been better epoxy putties to use here, since they will merely bend rather than break after they are cured/dried. Green stuff has a green finish while Procreate putty has a darkish grey finish. Milliput also comes in black as you can see with the black bits in the gondola which I've also molded ( I intended to use the black to create a caboose chimney at some point, black Milliput seems to have a smoother finish) :
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if you use too much putty in the mold, you may need to clean up the sloppy results, so it's helpful that milliput is easily sanded. I've heard that Green stuff and Procreate putty don't sand as well as millliput. You can mix Milliput with Green stuff or Procreate putty to try to get the best or worst of both worlds. I think all of the epoxy putties can be added to with more epoxy putty, so I was able to fill in the chips and replace the bit that broke off of the door. I also had to drill the hole in the new hinge:
125183_96b9accd7110015c6f620f37613ad12a.jpg


There are probably a few more touch ups I could make, and a little more sanding before I paint it, but it's nice that it was so easy to fix and replace broken and missing stuff:
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I haven't yet decided what color to paint the gondola. Any suggestions?
 
Xav204

Xav204

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Very Interesting
I would like to try
 
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-bbbb

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I've decided to paint only the new parts, but the paint dried a bit darker than I expected:
125515_39cb456d7f9d5f9b6af0d1fd954ac1e8.jpg

I still have to re-apply the stickers, handles, and figure out how to do a peroxide/sun treatment on the door latches without removing them.
 
Revok

Revok

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Useful info! Will give this a tryout I think.
 
P

Paradise

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I have ordered some 'Oyumaru' so will test it out. :nod:
 
korm kormsen

korm kormsen

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-bbbb

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If you plan to do something like this I'd suggest watching some youtube videos on the subject. instead of tongs I used a chopstick. I just boil the water, remove from heat, and put the stuff in the water after about 30 seconds of cooling, wait a few minutes and remove with a pencil or whatever. I can handle it a few seconds after removing it. It floats. The thermoplastic can be a bit pliable even when cooled, and the item can become warped if you press the putty in so hard that it bends the mold. Some people use a frame of some sort to support the mold when stuffing the putty into it. I used a wad of tinfoil, but you can use legos, plaster, or whatever. Two part molds can be tricky because it's easy to misalign the molds and end up with one side offset from the other. Putting a few dents in the mold to align both sides with is not good enough in my opinion.
 
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When I got the broken gondola, it came with this tipper car, with a bit broken at the lever holder, and it was missing the levers and roof:
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So I added some epoxy putty, and paint to fix the broken bit, and did a peroxide/sun treatment to the yellowed handles. I happened to already have an extra roof. Special thanks to James for providing the levers:
125547_e95187ed2cffede1a196477f47aa0b01.jpg
 
korm kormsen

korm kormsen

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... Two part molds can be tricky because it's easy to misalign the molds and end up with one side offset from the other. Putting a few dents in the mold to align both sides with is not good enough in my opinion.
that is, what i am using a pencil for.
when i press the original in the first part of the mold, around the piece i push three or four holes into the mold with a pencil.
the second part of the mold gets pressed into these holes. no more offsetting that way.
 
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-bbbb

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that is, what i am using a pencil for.
when i press the original in the first part of the mold, around the piece i push three or four holes into the mold with a pencil.
the second part of the mold gets pressed into these holes. no more offsetting that way.
That's what I was referring to. That method doesn't always work for me and others. You still have to be careful to make sure there's a solid(non-shifting) fit between the two halves of the mold. Maybe start by using the holes before focusing on how the mold fits the part?
 
korm kormsen

korm kormsen

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making the molds, first, i press the original into the first half-mold, then i push some of the mold material from all sides against the original. then i use the pencil.
then i press the edges of the second part first into the pencil holes, then i push the material from the sides towards the center, before i push downwards on the termoplast.
so i ge somewhat uneven surfaces, that help as well for a tight fitting.

i tend to believe, that mismatches and deformed copies might be often the result of too shallow molds.
as the material can be (re)used many times, thick molds are no waste of material.

but, the best molds - specially for making many copies - i made up til now are from two part epoxy, the kind used for plumbing.
that stuff gets as hard as stone (brandname: Poxilina)
 
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-bbbb

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Here are some video's I found helpful:
 
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-bbbb

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I'm using the same process to repair this broken coach, taking a mold of the good corner to duplicate onto the broken corner:
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However I'm using procreate putty this time instead of milliput. it's a bit different to work with( stiff like old chewing gum, more sticky, and reacts different to water ), but isn't brittle when cured:
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P

Paradise

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My 2 packs of 'Oyumaru' arrived so I put some to test. Each pack is about 2 matchboxes in volume. After being left in hot water it feels like chewing gum but not sticky then hardens as it cools to something like hard flexible silicone.
I have nothing to compare it to but it has a slight glittery pixie dust throughout which can be distracting when checking molded detail. All the colours are transparent with pixie dust.
Some softened Oyumaru was pressed over a Schleich figure bust and it kept the detail reasonably well. I then did something odd and put the mold in the freezer for a few minutes to keep hard, painted in a drop of veg oil for mold release then used the same softened substance to make a casting just for quick experiment.
It worked out OK but I intend to use something else for casting that is more suitable for carving, sanding and painting etc.

Below is not the 'Shroud of Turin' but looking into the hollow back of the mold opening with light shining behind to demonstrate how it can pick-up detail reasonably well. It's difficult to appreciate all detail as it changes on rotation when back lit. I'm sure practice can improve matters by pushing into detail areas and where the softened substance rejoins like under the cheek on RH. (The black specks are pixie dust silhouette).

Thermoplastic Figure Mold
 
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P

Paradise

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All of the colours you have contain glitter, or all of the colours available contain it?
Actually I'm not so sure now. :think: I have the clear glittery one. The other colours available may not be glittery but more translucent. Modern arty colours like mauve, purple, ocean green, white etc.
 
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