first the veins were too light then i lightly went over them and they looked perfect. WRONG!!! after i baked the limbs and took them out of the oven they were way too dark. They didnt look that dark before i baked them. Well i got another doll added to my collection. Tried fixing them but fixing blue is impossible. But i looked at my 3 yr old grandaughters arms and legs and her veins are dark so maybe all is good. I do know one thing i wont do veins for awhile.
Testing the color a little is a very good idea. I often will make a paint thinner trail first and then go over it with my vein color. Then I use a sponge to dab it as I go along. You could go lightly over it with a q-tip with acetone, but do it very lightly.
I used my winsor & newton brush cleaner & restorer lightly and it worked. It did take more paint off but easly to fix… Good thing i had about 4 different layers of skintone on before i applied the veins so the blue never soaked into the vinyl. I only did the veins that i thought were way to dark.