How can the light get past the spray paint?

Mehrabani1, I beleive that your turn lite bulb is 7507.Silverstar replacement is 7507A ST.They are inexpensive and a lot neater than spray painting.

Another point is that they flash Amber and look silver white

It just does, a light coat of silver spray paint, makes the bulb look clear when not on yet amber when on, it is an old trick that works great, no need to buy the expensive silver vision bulbs. Obviously you remove and paint the bulbs away from the car, not a messy job at all.