Lately I’ve been seeing a lot of customs on Yahoo! Auctions in Japan have been featuring modifications with “Sofubi Putty”.
I became curious and looked at a bunch of posts, tutorials, tweets and other things to find out what this wonderful mystery solution was.
I’m not really an expert so PLEASE PLEASE PLEASE use this recipe and technique at your own risk. For additive mods, there is a high margin for error which can result in making your head unusable.
※ Warning: I only tested this method on Dollfie Dream. I am not sure if these techniques will apply to other soft vinyl dolls such as Obitsu, Azone, Angelphilia and Smart Doll. This post is also written from the perspective of someone living in the USA, so I’m not sure about the availability of the products mentioned in the blog in other countries.
AS ALWAYS, PLEASE WEAR A RESPIRATOR AND WORK IN A WELL VENTILATED AREA.
A few years ago, I was under the assumption that Vinyl Thinner was my answer. Since V-Color is next to impossible to find stateside, I resorted to using CS Coating’s “Lure and Jig Finish” Vinyl Thinner.
Unfortunately the vinyl chunks never fully dissolved and just swelled in size. When applying the chunks to the surface of vinyl, it just crumbled and fell off.
However, this vinyl thinner did do a good job smoothing the surface of heads and reduced the appearance of sanding marks.
Later I found that the main product that people in Japan were using was a PVC adhesive by a company called Acrysunday.
This company manufactures plastics and produces a hard PVC board called “Sunday Sheet”.
To adhere PVC pieces together, the Acrysunday adhesive uses solvents to chemically weld the plastic together. Upon reading the SDS, it was clear that the key ingredient in this adhesive is a chemical called “Tetrahydrofuran” or THF.
The main use of THF is as an industrial solvent for polyvinyl chloride (PVC) and in paint varnishes. The vinyl thinner I previously used lacked THF which is probably why it never dissolved.
Unfortunately it’s impossible to import Acrysunday’s PVC adhesive due to its flammable nature. You may be able to stash it away into checked luggage but travelling to Japan is not an option at the moment.
Now since I knew the THF was my key ingredient. I started doing my own research into what I could use to replicate Acrysunday PVC adhesive.
It seems that PVC cement (for plumbing) contains a % of THF in their mixtures. Usually there are other additives such as Acetone and Methyl Ketone in the mix.
I purchased 3 different types of cements/solvents at Home Depot to try it out.
Since these solvents are pretty strong, I had to purchase glass bottles to create my mixtures.
For this test I chopped up some unnecessary DD parts that I had on hand and submerged them in a glass bottle.
Kinda Works but with Incomplete Slurrification
Weld-On P-68 Primer: Very low visocity, higher % of THF
Oatey Regular Clear PVC Cement: Medium viscosity, medium % THF
The above were able to dissolve the vinyl pieces but not to a fine paste. The pieces swelled and broke apart.
The chunky mix was able to adhere to the vinyl’s surface.
Vinyl retained elasticity after drying. Smelled like inflatible pool toys…
Oatey All Purpose Cement: THICK, creamy color, gross. Don’t waste your time with this.
I guess nothing really dissolved because the concentration of THF was not high enough. This stuff will work in a pinch though.
Sanding it sucks as usual though.
What Actually Worked
I was a little sad that the PVC cement didn’t work as I initially expected. However, I didn’t let that discourage my quest for DD SLURRY.
I ended up looking into my options to purchasing industrial 99.99% THF inhibited With BHT.
Apparently you can purchase it without a license in the United States… So I got a small can of it off Amazon.
You will need to purchase THF that is inhibited with BHT. Uninhibited THF can have the tendency to form the explosive compounds when exposed with air. You don’t want to make explosives when working on dolls!
In its inhibited form, THF is a relatively nontoxic solvent, but still handle it with caution.
Once I added the THF to my jar of vinyl chunks they immediately started to dissolve.
Within an hour the vinyl completely dissolved into my desired DD Slurry.
I used the DD Slurry to repair a cracked neck hole in a head and to smooth out the chunky additive mods that were left from the PVC cement experiments.
Tips and Stuff:
Use solvent resistant pipettes to control the amount of THF you’re using.
Unfortunately, the bottle is a little imprecise so pouring it out is a massive pain. Using a pipette will make your life A LOT easier. Trust me.
THF dissolves latex and vinyl(duh) so you need to use nitrile gloves. It is highly flammable.
Any hobby glass bottles will work to contain your DD slurry. Bottles with solvent resistant gaskets are preferred.
The THF in the DD Slurry dries reallllly fast. You may need to add more THF to your mixture if it gets too thick.
For better adhesion, I recommend roughing up the surface of parts prior applying the DD Slurry.※
This can be achieved by using low grit sand paper.
If the surface doesn’t have enough grip, the applied paste may peel off when you’re sanding.
※For neck hole repairs, you don’t really need to do this. However, if you want the repair to last longer, I’d recommend doing this)
It is dry to the touch within 2-3 hours, but I recommend allowing it cure for around 2 days before sanding. You want the THF to evaporate out of the vinyl completely.
Since the “bulk” of the DD Slurry is solvent, it will shrink as it dries. It will also dry a little glossy.
I recommend applying it heavy handed to avoid having to apply a lot of layers.
Please keep in mind that air bubbles may get trapped in the slurry.
Just a word of warning: Sanding this stuff actually really SUCKS though.
The added benefit is that you won’t need to color match the putty after application since you’re melting the original material!
In addition, the vinyl putty retains it’s flexibility which really nice. You wont really have to worry about cracking, unlike additive mods such as Apoxie Sculpt and etc.
By the way, the THF is actually really helpful in smoothing out sanding marks/jagged edges/anything not smooth on the surface of vinyl. If you are a little sloppy with mods this can help clean things up a bit. I have used this to smooth down uneven surfaces when widening eye holes and doing open mouth modifications.
For the time being, I recommend using this technique for repairs.
If you have a lot of will power and a lot of time to sand, then go crazy. lol I don’t have a lot of patience….
Anyways, I’m going to continue tweaking the recipe to see if I can get it to a better consistency for sanding.
I’ll try my best to document my modding adventure and final results of the application and creation of this DD Slurry.