Last week we covered how to prevent sun damage. This week, we're turning back the clock on items where it's too late to start preventing yellowing!
You may have heard about the 'retrobrite' solution. This is a method for de-yellowing plastic that involves high concentrations of hydrogen peroxide (brown bottle, probably in your bathroom for treating cuts) that was developed from hobbyists trying to reverse UV damage on plastic computer cases.
Hmmm.... reverse yellowing on plastic...
This is different from de-staining. It's supposed to JUST remove yellowing, so if the thing was originally pink and is now orange from yellowing, it should turn pink again.
Let's give it a try!
Here are the subjects of my experiment:
- A 1960s Ken doll (who may be yellowed, I'm not sure. His head/arms/legs are slightly darker than the torso, but only slightly. He's actually in great shape for his age, but I included him in here because he has a lot of pigment, so if he gets bleached out it will be obvious)
- A piece of yellowed Barbie furniture. I picked this one because it is only partially yellowed, and because it has a glossy surface which generally means less porous, so may be harder to treat.
- An extremely yellowed Pullip. Pullips have multiple types of plastic in the body, and they are all yellowed: the soft vinyl torso, the harder head, and the hard-but-different-from-head plastic limbs. The head is turned because the most yellowing is on the temple, at the side of the head.
How do you de-yellow? You need 3 components: Hydrogen peroxide in a semi-liquid state (so it stays where it's applied. I used Vol 40 creme, from a hair salon. You would mix this with bleach to lighten hair, or hair dye to help the dye take. We're not mixing it with anything), UV light (can be provided by the sun or a light bulb with UV spectrum) and HEAT. About 100-160 degrees Fahrenheit is the range of 'warm enough to work but not deform the plastic.'
DO NOT SKIM THIS PART:
Heat and strength of peroxide are variables that you can control for more/less de-yellowing effect. You can go too strong and too hot, and if you do, you will get uneven de-yellowing (vol 40 peroxide on a 95+ day will get your surface temperature up to 160 easily). For a more controllable de-yellowing, use 30, 20, or 10 volume on a sunny day with the temperature 75-85. It will just take longer.
How to do it:
I shook up the bottle of vol 40, and poured a little into a tin can. Then I used a paint brush to apply an even coating to the surfaces I wanted to de-yellow. However, doll heads are not smooth, so it's impossible to have a truly even coat. This is important, and I'll address it later.
After the pieces I wanted to de-yellow were coated, I wrapped them with saran wrap to keep the solution from evaporating and set them in the sun.
Really important part: I did not set and forget. I went outside and checked on the pieces every 20 minutes or so, turning them so that the sun would light/warm all of the surfaces evenly, and rubbing the surface of the pieces through the plastic wrap to re-distribute the gel coating, to make sure things faded evenly.
When you start out, areas with more gel fade faster, but if you squish around the gel a lot, everything fades nice and evenly. Over time the gel bubbles a bit and turns more pasty in consistency.
Day 1 was cut short because of thunderstorms, so it only resulted in about 3 hours of treatment. The pullip was perfect at this point, so only the other 2 items went out for day 2 (which was much hotter, and about 8 hours total of sun exposure)
At the end, here are my results:
- The ken doll was unchanged. He was the one I wasn't even sure was yellowed, but more importantly, he experienced no bleaching effects. The factory paint on him was undamaged
- The furniture console was lightened, but not completely de-yellowed (more on that later). The paper decal was undamaged, but may have been lightened from purple toned grey to blue toned grey.
- The pullip was completely de-yellowed. Most of the custom faceup was left intact, though the sealant on the lips was dissolved along with the gunk from a wig that had previously been affixed with glue. I thought it was superglue and that I'd have to sand it off from the way it was stuck to the forehead with bits of the wig embedded, but it softened up and came right off.
Now the retrobrite guys originally thought that it was only UV + hydrogen peroxide that was at work here, and covered the items with plastic to prevent evaporation. Some later experiments indicated heat played a part. I have my own thoughts to add:
1. Heat is definitely a factor. I've seen plenty of plastic items go into a dark attic and turn yellow where no yellowing existed before. This is why if I store dolls, I store them somewhere cool like the basement if I can't keep them in the temperature controlled house. I suspect it's because heat makes plastic more porous, which lets the chemicals penetrate more easily.
2. The plastic covering doesn't just hold in moisture, it holds in gas and the gas released from the hydrogen peroxide as it goes from gel to paste form is AT LEAST as important in de-yellowing as the hydrogen peroxide itself. I drew this conclusion from two observations: First, gas would collect in wrinkles on the plastic wrap, and the area under them, though not as covered in gel, would de-yellow even faster than areas with a thick gel covering. Second, the plastic furniture was not uniformly covered because of the shape. The legs and flat outer surface were covered snugly with saran wrap, but the inside of the box area was not. Evaporation was prevented, BUT there was no high concentration of gas building up under the saran wrap close to the plastic surface. The parts without the surface wrapping had the least de-yellowing observed.
3. This treatment removed yellowing but not other kinds of stains. There were a couple of marks on the pullip that I observed to be stained (a red spot that looked like dye-leech and a brownish spot that looked like dirt). This is a good thing because again, it supports evidence that this is a 'safe' treatment. Plus, I know how to clean off dirt and de-stain with other methods.
Let's see how nice and clean those legs are now:
Fresh and peachy, just like the day she was made <3
I didn't test this method on BJDs because mine aren't yellowed. There is no reason it wouldn't work on them, because...
RESIN IS PLASTIC
Got that? It's a type of plastic, but absolutely, plastic. I keep seeing people saying things like "Oh, I don't like plastic dolls, because they're PLASTIC. Resin is just such higher quality!"
Nope. Resin is plastic. I've cast it myself. Google it. Plastic. Resin is not porcelain, or a product of any kind of clay. Plastic.
So in closing, if you want to try this out, remember: pay close attention, go slow, and if you can, do a test on something you don't mind destroying (this experiment was me testing before I try it on non-junk items) so you can refine your method for your local climate and the specific kind of plastic you want to work on.