hi there,here's a method i use when i paint my 1/72 scale figures, i soak them in a container containing bleach, soap and water, it's really potent and smelly as it creates a gas, but it removes all the manufacturing oils, then after a couple of hours, you can do this and let them soak overnight, then rinse in hot water and let air dry, i've not had a problem at all with any of my figures holding paint, then i hit them with a clear-coat, either gloss or dull, hope this helps you out, it does me and i've painted well over a thousand from different eras, only 900,000 more to go.