I have 10 old (20 years) Roundhouse passenger car kits that have 2 formed wire handrails to go on each end. I have a spray can of Yellow paint and I want to spray them all at one time before I glue them on. What should I hold them with and do they require cleaning before painting?
The require cleaning - 70% isopropyl alcohol will work fine.
You need to prime them with light grey primer, then bake the primer.
Holding - I would stick them into high density cork or Homasote®.
Probably not the best way or the easiet way to do it. There is a Japanese paint company (Tamika?) that makes a very flexible paint that seems to work the best on handrails. Since yours are metal that may not be neccesary but a brush is the way to go. I would paint the ends that go into the car by laying them on a piece of masking tape with the car side up. Just do the ends so there are no holidays when you install them. When they have dried stick the painted ends into a piece of foam and paint the rest. You will still have some touch up after installing them but it will be minimal. If you do need to touch them up slip a piece of something like a 3"x5" card behind the handrail so you don’t slip and paint the car. I usually just install them and then paint them using a minimal amount of paint on the brush. With a fine brush it isn’t too hard to do. If you want to use that spray paint just spray some in a small container and dip your brush into it.