This is basically a visual representation of what couture means. Every one of those heavily detailed/embroidered/beaded couture gowns you see during haute couture fashion week is made this way. In order to be considered couture they have to be, but that’s a separate post.

We all have our gripes about doll collecting, but there's one request that consistently drives me a little batty in the BJD collector world: resin matching. People will ask, "Can you please take a photo of a doll in this resin color and see if it matches that doll in that resin color?"

Hrrrnnnnnggggghhhh.

BJDs are made of 2-part epoxy resin. You buy two jugs of resin that you have to mix together and pour into a mold. A chemical reaction happens (rapidly), and the resin solidifies in the mold. You let it sit in there for a bit until it hardens, and then you pull it out.

This is what the two jugs of resin look like when you buy them:

They're clear. No color.

Every single ball-jointed resin doll I own was made with clear resin that the artist had to add color to. Now, companies generally have a "recipe" of color that they add to resin, so that resin colors are fairly consistent across a line of dolls. And sure, some 3D printer resins come pre-tinted.

But guys. Folks. People. You're never going to get a perfect, planned resin match. When you do, it's basically an accident. A happy coincidence. It's highly unlikely that resin will match when you buy parts from the same doll company at different times. Resin is a finicky little bastard. It cures differently depending upon the day, the humidity, whether it's in a good mood... Also, resin changes color with time and exposure to stuff like air and sunlight. So a doll you've owned for a year is going to be slightly different from the same doll made by the same company in the same color today.

When I see people painstakingly take photos of different resins from different companies, carefully labeling each head cap, I think, "Dude. Bust out some acrylics and just paint it."

Cuz you're never going to get that perfect match, except totally by accident.

And that's why I don't care if my resin matches. I know I'll either dye or paint the doll to match.

It varies a lot depending on the quality of cast you want. For the best stuff you need pressurized vessels and space to handle very toxic chemicals. Googling “BJD casting” provides more details than anyone here is likely to know. This site looks interesting: https://atriphene.wixsite.com/bjdwtf/make-your-own-bjd

I know a little about manufacturing plastics but it’s not my specialty in materials engineering. I don’t know enough to estimate the cost of production off the top of my head :( You might also consider 3D printing (specifically SLA, which is UV resin with a better resolution than ‘traditional’ 3d printers)

Mirrorada offers 3d printing services for sculptors and Harucasting offers traditional casting services for sculptors, both great options to look into and probably much, much cheaper than getting the setup yourself

To continue, mold life is a bit more complicated: certain things degrade silicone faster than others. Switching between types of resin or applying heat can do this, as can using epoxy resin a lot. For BJDs we use polyurethane. Basically to simplify the way that works, there are 2 components that are liquid, when you mix them there’s a chemical reaction and they solidify. That reaction actually generates heat, which can contribute to degrading and warping the mold. In a high-volume process maybe you’d do this reaction in a cold environment, but that’s not very practical for casting dolls. All this to say, what I’ve heard is for PU resin you can use the mold 15-20 times, and the first cast will be junk. I haven’t witnessed this myself, just repeating what I’ve heard, but look at casting services and the cutoff numbers where their rates increase or decrease--that probably has some relation to when molds degrade and the minimum/maximum casting they can handle at one time.

Also keep in mind that casting PU resin involves some very dangerous chemical and you need appropriate PPE and a safe, well-ventilated place to work; in some locales, it might not be legal to work with certain quantities of these chemicals without a ‘booth’ and a location with industrial zoning. In other places it’s perfectly legal. And if you’re casting just one or two parts, it’s usually such a small amount it doesn’t matter legally, which is why you can get 2-part resin in craft stores (just at a much higher price, and not enough to cast a whole doll unless you buy all their stock).

Regardless, always google the product name + “SDS” (safety data sheet) to see what the health warnings are (absolutely essential!!!) and check what your local laws are (less important than safety but still). Here’s the SDS for Model Pro 2-part resin. Part A is an isocyanate and has similar hazards as methyl isocyanate, the chemical involved in the Bhopal Disaster. It’s best to handle these chemicals as recommended by the SDS, and with a healthy respect for what they can do.

~Anonymous

Mod: gonna be a bit controversial and daring and make this into a poll: