I'm not talking rattle can paints here but painit that must be reduced and sprayed such as automotive paints or othe industrial finishes. While some may swear by Rustoleum, IMHO it sucks. It uses a very slow temp thinner, so it takes a considerably longer time to setup tack free or get to the point of being able tobe handled. You can use naptha and some thinner called VG & P or something along those lines which is a faster reducer and sold in most paint or home builder supply stores, but Rustoleum prefers you to use their brand of thinner. Their primer also leaves a lot to be desired, as it takes so long to dry, and its hard to sand if your after a nice finish.
But take automotive paints as a whole (no brand names in particular) and they are suited to only spray application. Its a real pain to even try and brush as small area with an automotive spray paint, so don't even try it. Its made for spray application only. YOu can use different temperature sensitive reducers so you can match the ambient air temp your working in with the paints / reducers drying specs so it still will dry quick at low temps and not too fast at high temps. You can even use regular lac thinner in most any automotive primer or finish coat, for a reducer even if it is a enamel base finish. Some colors may blush when you use lac thinner / reducer but if its allowed to dry without much humidity or if its painted inside this is not a problem. There are a few colors lac thinner used in enamel will show the blush more than other colors, but its mainly in metallic based paints.
Usually the smallest container size is a quart unless you go with a lac then you can get pints, but considering that the paint is thinned considerably before use, its a lot of paint for the price.
Imron (Dupont brand) and others like paints are super hard and durable, however they will chip and scratch so they are not bullet proof, and cost more than regular acrylic based enamels do. Bigget problem with Imron and other like products is touch up at a later date, unless it has been changed and a work around has been found since I learned this, is touch up is hard to do on Imron type paints, as usually an entire surface has to be refinished for it to work right. This is not the case with acrilic and standard enamels, as they can be compounded in and blend in quite nice........its the way standard automotive refinishing touchup has been done for years and still is, although sometimes refinish of entire panel or part is easier in some cases.
There was an old wifes tale that if you used silicon carbide sandpaper it could lead to fisheyes, as it leaves a residue behind, So if it was not rinsed and cleaned properly after sanding with S-C type paper you could have problems. This is pure bull$hit. Silicone and silicon are two different animals. One is in lubricants and sealants the other is a hard mineral and not related to each other, so wet or dry paper will not leave any residue other than dust etc behind that will make a fisheye appear.
Unless I was gong to show the equipment in a show or have it on display I would not spend the money on acrylics, but would use the base line enamels, as they will hold up just fine and are probably inline with what it was painted with to begiin with.
You'll save in the neighborhood of 50% of the price by going with standard enamels of automotive paints over using acrylics and a lot more saved by not going the Imron route.
Hardener can be added to most paints even base line enamels, and its standard practice to add them to most acrylics but then again it makes the paint chip if it gets dented, whereas it may not have chipped off so bad if hardener was not used.
You wold be surprised how easy automotive spray paints made for spray application go on as compared to trying to get a finish with Rustoleum and other types of paint thats use is primarily inteded to be brush application.
And don't foregt to pick up some tack rags if your looking for a nice nub free finish. They are dirt cheap and do the job or removing dust and lint, that you otherwise think you wiped or blew off the surface, trust me a tack rag will find all kids of stuff you missed.
Primers are available in many forms. Sandable and non sanding. Non sanding does not mean you can't sand it, but its maian use is for new items that should be able to be primed and painted without the need to go back and fillin tiny imperfections. Its hard sanding but still sandable. Sandable is usually meant to be used as spot repairs and filling in imperfections, and prime again fill some ore missed areas and prime again and then finally a wetsand before finish coat application. You can get primer sealers which work fine if yur applying paint to a surface previously painted that your not sure is copatable with what your applying to it now. There are primer fillers, which are a heavy body primer made to fill slight imperfections by buildup of primer . These usually require a final wetsand before finish coat is made. Dupont 131S is one such primer. Its very heavy for a quart can of this stuff and pretty pricey, but it does a great job.
No matter what brand you go with all of the major manufacturers have like products, as well as lower grades of paints at varying prices. All makers have one or more brands and most are really the same product but in different packaging.
You can use glazing putty (red lac or green lac putty to fill imperfections, but since its a solvent based filler it is prone to cracking and poping out. It needs to be applied over a primed surface, so don;t apply it to bare metal as it more than likely will eventually ppop out. Same for previously painted surfaces when using lac putty. Its best to hit the surface with primer first then apply putty, as it can make the spot blister at a later date due to reactin with the previously applied paint. They make a 2 part scratch and imerfection filler that works great and is not prone to the problems associated with lac putty but its more $$ but depending on its application may be worth the extra money to use it. Its mixed like bondo is.
Bondo should always be aplied to a bare metal surface, as if its on rust or primer or finish coat its eventually going to turn loose and crack and come out in that area as it does not adhere well to paints etc, even if it gives you the impression its stuck hard and fast.
Give the automotive paints a try, and I bet you will like them. No paint truly hides any imperfections. All it really is, is a different color to whats already under there.