Vinyl Head Shrinking:
The Slow Method
Please be sure that you have read the Introduction to Vinyl Head Shrinking before taking on this tutorial. There are a few chemical conditions talked about there to consider before jumping in.
If you are ready to continue, you can either watch the video below,
or read the written version below that.
So you have chosen the safer path! Though it is not without its risks, things are more likely to go well here.
Step 1: Gather materials
Materials you will need:
Glass jars: I use 16oz 3.5"x3.5" mason jars for what these days are your average 11" tall doll. It is VERY important that you use a jar that is large enough. 8oz 2.5x4" jars are NOT large enough and your head will crack at the thinner parts of the vinyl without enough room to expand.
100% Pure Acetone: Acetone is commonly sold as nail polish remover, among other things. Wherever you go to shop for your acetone, make sure that it is actually pure, with no other chemicals, like things to strengthen your cuticles or want not. Any impurities at all can greatly stunt the effectiveness of the acetone or result in unforeseen side effects. After all, diluting it with even as little as 10% water is what weakens it enough to result in the slow method we are using here. Weak enough that it doesn't even remove the face paint.
Water: Easy enough. Plain old tap water.
Springy Stuffing (optional): If you are working on a head that has very thin walls like Rainbow High, they may be susceptible to sagging after they have been softened by soaking. If this is a concern, you can put some stuffing inside the head that will help it to keep its shape, but make sure not to stuff it tightly, or that could cause other kinds of distortion or tearing.
Step 2: Prep/Cleaning
To optimize results, you need to reduce as many contaminants as possible so you take the applicable steps:
1. - Remove hair if you are going to reroot. This will also reduce the amount of acetone used getting soaked up in the hair.
2. - Wash the head. Just some dish washing liquid in tap water should suffice to get rid of any oils and grime. Make sure that the soap is completely rinsed out.
Step 3: Soak(s)
When I made my first version of this tutorial, I advised 1/3rd water 2/3rds acetone mix. That's still fine, especially if you are hurting financially, but since then, I've shrunken over 100 heads and I've found that I can use as little as 10% water to bring the acetone to a level that is very effective, but won't blow the heads up very much. This maximizes the process while still keeping the risk low.
Whatever ratio you decide on, make sure that you fill the container enough so that it will still cover the head in its inflated state. Don't forget to stir the solution. I know that's obvious, but I've almost forgotten to before and can just imagine part of the head totally distorted from this mistake lol.
Soak the head for approximately 48 hours. It's a very loose estimate. A few hours early or late shouldn't really make any difference. This should be plenty of time for the diluted acetone to slowly work its way into the vinyl and break down some plasticizer. That's the stuff that gives vinyl its elasticity and that's what we are getting rid of to facilitate shrinkage. That's why the vinyl gets so hard from the process. I have many dolls that I shrank 5 or 6 years ago and they show no signs of becoming brittle or discolored defective in any way yet.
Back to the job: The head will be somewhat inflated and softer and can be fragile now, so try to wrap your fingers around it to take it out, or if you are going to dump that batch of solution and mix a new one, you can just pour it out. If you are trying to preserve the faceup, make sure not to touch the face. Try not to pull the hair. Rinse the hair gently to get rid of any particulates from the soak that might be clinging in there.
At this point, if it seems like the sculpt is sagging and might dry in a warped shape, you might want to put some of that stuffing in there. Just enough to avoid cave ins. Don't stuff tightly.
Drying times will vary, but 48 hours should be a good amount of time to allow the acetone that's in there evaporate, letting the head get smaller and harden back up again. Sometimes it can take WEEKS for a head to completely finish drying and shrinking, but that doesn't mean you have to wait that long between cycles. At this point the evaporation is probably done, so it is ready for the next soak where it can absorb more acetone to break down more plasticizer. That's if you want to do as much shrinking as possible. If you only want to shrink a little, you should probably wait till it has completely solidified again so you can make a more accurate observation on the progress and avoid overdoing it. Sometimes it will still shrink more even after you're sure it's done.
I usually do 3 or 4 soaks, depending on what I'm going for and how the progress is looking. Sometimes even just 2 soaks can result in such drastic shrinkage that I don't have to go further.
Now the thing about subsequent soaks is that once the solution has been used, it is no longer 10% water and 90% acetone. Some of the plasticizer has become leached out into it, as well as any number of unknown particulates in unknown proportions. So unfortunately, as I mentioned in the introduction, without a lot of expensive lab equipment, a lot of guess work comes into play here. Well, unless you've got enough money to mix a fresh solution for each soak. Not everyone out there is shrinking en masse like me lol.
Unless the mixture has turned a strong color (say dark pink from color leeching from the hair [funnily enough, this has never actually changed a doll's hair color in my experience]) then the worst thing that can happen if you try to use the same solution again, is that it won't be very effective. The coloring has a chance of dying the head, though that has only happened to me twice out of 14 times the solution has become colored and both were dolls that had been rooted with yarn.
Personally I usually dump the first batch of solution and then reuse it after that unless it gets cloudy or discolored.
Below you can see a picture of some discolored acetone that I would dump, and the other picture is just for fun. While usually you can't see much of interest besides bits of plastic or glue in used solutions, I had these 2 jars that sat in my craft room for 5 years. As you can see, after all that time, some various materials have separated. This was from shrinking a head from one of the 17" Monster High dolls, so guess that's quite a bit of Frightfully Tall Draculaura in there!
But wait! We're not done yet!
Step 4: Things to do During Drying
There are a number of things that you can do during the final drying stage, all of them optional, depending on your desired end result. Before you do any of them though, it is a good idea to wait at least 12 hours to allow things to stabilize and strengthen a bit.
Rerooting: If it seems like it is hardening very quickly at this point, you may want to begin rerooting if you want to be finished with that before it gets too hard. You can still root in a solid head, but it's more difficult.
Neck fitting: I wouldn't put the head back on the body until it's solid enough that it's not squishy, but has some give if you squeeze hard enough. If you put it on too soon, it may melt the plastic a bit. It will likely be very difficult to get the head off again, so make sure you do everything you plan to do before securing the connection. It is a good idea to widen the inner neck hole a bit with an Xacto blade, because even if you can squish it on while it's soft, the head shape could distort a little on the lower head as it tries to shrink around the neck. Be careful not to widen the inner hole TOO much, or there will be nothing for the head to sit on and it'll just sink down to the shoulders.
Compression shaping: You can alter the shape of a head by compressing it during drying, using any arrangement you can think of. Ever After High dolls are some of my favorites out there but many of them have very round faces that I don't care for. So I use a mini-vise, rubber bands, some padding and a box to dry them in a more oval shape with a more pointed chin.
The box is to contain the configuration since rubber bands will sometimes want to slip off, or others parts pop out of place. Makeup wedges are good for padding directly between the head and the vise grips, because if you don't pad, you will end up with hard lines pressed into the vinyl from the edges. Make sure to check back every few hours to see if you need to make any adjustments as the shrinking progresses.