"Made in Japan"

For sure the mold surface is a faithful replication of the original surface, but I still wonder if they actually polish. I think with metal deposition, your mold surface is probably going to be as smooth as your wax-up is. Perhaps it is the Chinese molds that are sand blasted, resulting in the matte finishes that we observe. Regardless, it sounds like too smooth a surface is problematic for getting the vinyl to slosh around throughout the mold.

I think certainly the heat/rotation ratios are going to vary anywhere in question and with different vinyl formulations/machine types, but I don't think that the Japanese molders are using any pressure to manufacture these. If you look at the Obitsu production pictures as an example, the slush molds are open designs to facilitate pouring out the excess material after the spin cycle. Besides, to apply pressure entails an entirely different system of molding, and mold tooling. Unless I am mistaken the Japanese are probably not using anything comparable to injection molding for vinyl toys. There is no way to create an injectable mold of any complexity that would economically facilitate these limited production runs. Limited runs are a hallmark of roto/slush molding because you can slap together a mold cheaply (cast aluminum, or metal deposition) that doesn't have to endure the mechanical stresses of injection molding (i.e. extreme pressure).

It is ironic that this is how these pricy toys are made, but I wouldn't call rotomolding a crude, shitty process. It is definitely a simple process, but elegantly so. It also remains perfect for hollow items, and as you point out, incredibly cost-effective.

I think the hardness/thinner wall thickness of the Japanese vinyl is merely an artifact of material and technique employed. Even within Japanese toys, there is big variation if you consider the difference between the body of a skullbrain, and the outer brain covering---completely different vinyl formulations to be sure. China does put out some nice translucent colors, but you have to get them in polyurethane which is another beast altogether, and more along the lines of the rubbery "dog chew toys" which you are fond of referring to.

I can't wait to hear what details you find out when you check out the scene in Japan.

 

The information being provided is awesome. Thanks very much!!!

 

Fess up Bri! You holding back some more info from us?

On a technical note, now I am wondering how you would go about polishing a mold that doesn't have a part line (since I don't observe part lines on rotomolded Japanese toys {and nor should there be any reason for them}, since it is rotational molding). If it is a one piece mold that does not come apart, how do you polish the inner mold surface? Chemically?

You ought to be able to polish out imperfections in your original model with judicious use of wax solvents, providing you are going to get a pristine plated mold surface ultimately...a cast mold is another story.

 

I have nothing to add except a heartfelt thanks for this discussion.

This has been one hell of a fascinating read. I love reading stuff like this. It makes you appreciate the toy even more.

Thanks for the insight!

 

the molds are polished with like a ball of fiber on the end of a drill.

it's a pain in the ass, at least in the metals industry I have experience of. all that shit has to be done by hand.

 

I also know that they use a vacuum chamber to de-bubble the vinyl before pouring..another step not done in China.

 

I found some pics on the Ampro site of them pouring concrete mix into the molds of the devilfish to prove the production was limited. At least this is as it looks.

I think Sunguts does some "home brew" vinyl in silicon molds. I know silicon can take high tempuratures, although it shortens the mold life. There's also pics of hot vinyl bubbling over and catching fire on a stove.

This is all conjecture without translation. I need to find the links.

 

I make a lot of silicone molds for resin pieves for the big 1-ff projects and i can tell youi its a pain to keep the silicone mold from coming out shitty or getting dirty, so i do not think silcone molding will work for more than like 10 pieces ,tops.

I know they do make hi-end silcone molds for prototyping wrk here, but usually they only cast 1 or 2 pieces and a big silicone mold easily costs several hundred dollars in materials alone.

a typical small mold I make that is maybe a 3 or 4" cube is like 40 bucks worth of silicone.

a mold for something like a Blobpus would esilty be 6-8 times that volume of material.

 

This is so cool.

 

It is feasible to make your own...but the quality is gonna be pretty low.

Look at Bemon..some of you have them. THAT toy is totally DIY effort, and while it has its own sort of charisma, the actually qualiity is sort of horrible.

 

Thanks to all who contributed to this.

It is the most informative thread EVER!

 

I get obsesso.

one day we need to have the milliput vs maigcsculpt debate

 

Milliput is finer.

 

I'm looking at all the toys I've bought and reading this thread and so happy I took the time to acquire them... I love them but I appreciate them and their makers so much more...THANKS for this thread and all the information you guys.

 

wow, I take back what I said and sorry geo if I've caused offense.
F-the other stuff. Such insightful info on the process, any more info?

 

Yes, I posted some pics a loooong time ago of Ryuuji of Amapro retiring a mold with the concrete fill to ensure that no more pieces get produced. (at least from the original master mold)

In this case, it is the spider design, "Kumokata."

 

Frank, have you ever tried any of those techniques where you paint on a thin layer of silcone (made more viscous with a thickening agent) and then craft a rigid plaster mother mold around the outside of the whole thing?

This was a technique we used to use in bronze art foundry casting. It adds more steps and can be a pain in the *ss, but you can save mega bucks on silicone expense because it hardly requires any at all.

 

Your time and temperature profiles during molding are critical to avoiding this no matter what you are doing. Immediately after the bubbles disappear in your 'cooking' cycle, the plastic will begin to deteriorate. So there is a fine balance between avoidance of bubbles, and ruining your piece by cooking it for too long (in an effort to let the bubbles diffuse out of the coalescing powder particles).

To be fair, many of my translucent Blobpus figures have some large bubbles scattered around inside of them. Maybe it reflects the "doing it with scrap materials after hours" ethic.

I was also reading about the addition of plasticizers to soften the vinyl materials. I wonder if this is how they obtain the squishy PVC.

 

Good god that does sound like an immense pain in the ass. Especially as I look around the room at the vinyls I have. In some cases it sounds almost impossible.

I was considering trying to make my own roto-cast vinyl toys, hand on, not subcontraced out, and ran butt-up against the problem of how you assure that the investment is all of the way out of the inside of your one piece mold AND that the surface is clean enough for casting. Conundrum!

My brother and I - both with bronze-art/lost wax and vacuum casting foundry experience - wracked our tiny brains trying to finger it out. We posited this very solution ("polished with like a ball of fiber on the end of a drill") then chucked it out as ridiculous; too difficult, too problematic. I still think so but I will defer to FK's greater knowledge.

Wotta pain in the ass.

I still think that, if you could create the mold yourself, you could easily contract the casting here in the US with an existing company and cut your costs in half. Of course, quality of the casting would be the next issue . . .

 

Got it straight from my manufacturer in China. They do not polish the mold unless you want to pay for it. It can be done for a fee which I thought was resonable to have done. It was like another $700.00.

Just my two cents. Most everything else typed here is very accurate. Kudos to Hyper and FK for the lessons! And who could forget little B. Flynn.

 

I'm curious about the one piece mold. How do you retrieve the figure from the mold? I was under the impression that it'd have to be a two piece mold so you could open it to retrieve the casting. I've done some plaster casting in the past and am looking to get back to doing some sculpting/casting so the idea of a one piece mold has my interest.
(And yeah, thanks to everyone for all the knowledge dropped! This has been great!)

 

Have you ever heated up your toys with a hairdryer? When fresh and warm, the vinyl is very elastic and deformable. I have seen pictures where basically the workers are yanking the toy parts out of the molds. It is this ability to deform and remain flexible at that time which enables the use of a one part mold even with substantial undercuts.

 

You raise some interesting issues. I agree that the fiber ball on the end of a flex shaft sounds kooky in some instances. There must be many little mold crevices which are impossible to polish.

In your case, why not just go to a split mold design? There is nothing to say that you can't, and if you are investing and casting to produce your mold, you pretty much need to in order to blast your refractory particles off of the mold surface. Traditional roto-molds are at least two part and clamp together after introducing the casting medium before the cycle. Slush molds are typically one part (although a given toy may require many molds-each being part requiring one) because the material is just dumped in and later the excess is poured out after the rotational cycle.

Plenty of rotational molds have part lines, so it is a viable technique. My previous postings only alluded to the fact that you don't need any split molds when you are starting with a mold such as electroplated nickel, etc. Since it sounds like you are going the cast route, it sounds almost mandatory for that situation.

I am sure you could find a company to play around with something here in the US like you say (especially if you have a mold) but I suspect that it would be a lot pricier than in China, and probably require a huge minimum order. Your materials would probably be different than those we see in the Asian toys as well...

 

Huh! I woulda thought that would scar the vinyl. Or does it and they just buff it out while it's still warm. Interesting, either way.
But I guess I'll have to use 2 part molds - everything I hope to do will be rigid (plaster, resin, metal). Woulda been nice if there was some secret magic trick to using a 1 part mold for a rigid cast (without destroying the mold to receive the casting)!

Here's another idea I've been thinking of: Sculpting your piece, creating a two part mold and then casting multiples in wax. Clean up the wax casts so there aren't any seams, etc and then create multiple 1 part plaster molds from the wax casts. With the multiple molds you can then make a single cast out of each plaster mold - destroy the mold to retrieve the cast. I don't know if all the work to create multiple waxes and molds would be worth the end results - but as you can tell, I'm trying to think of ways to use 1 part molds and still be able to create multiples.