Absolutely remove the old paint first, gently with paint stripper. Then immerse the hands in a solvent such as cellulose thinner or trichloroethylene, (hairspring cleaner). Place the hands on a spike through their holes, holding steady with rodico. Thin Humbrol paint to 50% and use a clock oiler to stroke the paint along the hands from the holes to the end. Thinned paint gives a very flat finish. Leave the first stroke for 2 hours then coat again. Then leave for 48 hours for the paint to harden.
You may need to practice painting hands first.
Hope this helps.
*I found that an electric coffee stirrer with the scoop mostly cut away is a great Humbrol paint mixer.
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