Why Is PVC Used for Figures?

PVC (Polyvinyl chloride) is the third most widely produced plastic after polyethylene and polypropylene. PVC is used in construction because it is cheaper than more durable and long-lasting alternatives such as ductile iron. It can be made softer and more flexible by adding plasticizers, the most widely used plasticizers being phthalates. PVC is a thermoplastic, which is a polymer that becomes liquid when heated and freezes into a rigid state when cooled sufficiently.
PVC will begin to deform at any temperature above 60 degrees Celsius (60 ºC = 140 ºF).

Materials and Models

The main reason PVC is used in model making is that it is very cheap and somewhat resistant compared to other plastics. Since PVC is a thermoplastic, it is easy to process and is recyclable.
PVC used in making scale models contains a small amount of plasticizers so that it is not too rubbery and soft. Good quality PVC feels smooth to the touch and has a skin-like appearance that cannot be achieved using other plastics such as ABS.
PVC is also very brittle and has a low resistance to high temperatures and pressures. These two factors can cause the PVC to bend or deform in other ways.
A good example of PVC uses (albeit for models) are Nendoroid heads, gashapon toys, some prize and trading models, the upper body of models, etc.

Cleaning and protecting your models

PVC sometimes releases oil. It's not common, but it does happen and there's nothing wrong with that. If this happens, it can also mean that the temperature is too high and the PVC is sweating.
PVC is a plastic and, like any other plastic, it's waterproof. If your model is dirty or greasy, you can wash it with confidence (but don't scrub it, or you might damage the paint).
If the model is difficult to wash manually, soak it in water with detergent (or liquid soap) and leave it there for about an hour.
After that, wash it again with running water and let it dry naturally or use cotton balls and maybe a flannel, but be careful. While there's no harm in washing your models, you shouldn't do it too often. Two or three times a year is enough.

Under no circumstances should you use cleaning chemicals, alcohol, or anything other than soap. Any chemicals can cause discoloration and damage the PVC and paint. The same applies to ABS, vinyl, cold cast, resin.

Dealing with tilt

As I said before, only models made entirely of PVC will tilt. PVC is a thermoplastic, so if heated, the tilt can be corrected by re-bending the model and using warm water to soften the PVC.
You can also use a hair dryer to heat the PVC, but I don't recommend it. A hair dryer will heat the PVC too fast and too hot, which can damage the PVC itself or the paint, while warm water will not.
If you use a hair dryer, once you have managed to bend it back, wash the part you heated with cold water so that the PVC will be hard again, but in the correct position.