After Googling a few sites, I'm seeing that your stainless likely needs to be cleaned, sanded and then a wash primer, vinyl primer and finally, enamel topcoat of your choice applied.
Stainless steel is relatively inert, hence paint adhesion could be a problem. Paint adhesion to stainless steel is enhanced by using pretreatments. Hydrofluoric acid etching is a pretreatment. Surface abrasion is a pretreatment. Wash primers are also pretreatments. I don't like to recommend hydrofluoric acid etches because of the safety hazard. It must always be used under controlled conditions. When people use dangerous chemicals, I generally issue the following caveat: Don't do this at home kids!
You can eliminate the hydrofluoric acid if you roughen the surface by abrading. This can be done by sanding, wire brushing or media blasting. It is important to note that the first step in any pretreatment is surface degreasing. After degreasing and abrading, apply the wash primer as soon as possible. After the wash primer has dried, the topcoat or gel coat can be applied.
Since you are using stainless steel and corrosion is not a major issue, you can eliminate a corrosion resistant primer. Otherwise, a corrosion resistant primer such as a two-component epoxy should be applied over the wash primer and before the topcoat.
As long as you first clean the metal off with rubbing alcohol & a clean rag & don't touch it. Then you can use any kind of enamel spray paint, as long as it's not water-based! I would use "Rustoleum". It's made to hold up to the weather & outdoors!
Add your voice to the conversation. Click here to answer this question.