In Reply to: Re: Buford posted by Jim on December 05, 2018 at 18:00:38:
Depends on what you want from a paint job.
No real downside to non hardened paints. THey were used in all industries for decades.
Catalyzed paints are harder, a little glossier and more fade resistant.
I shot an equipment trailer with RUstoleum acrylic enamel that I dumped who knows how much hardener into. It was a rough equipment trailer so no big deal if the paint didn't turn out show quality, how ever it came out well, standing up to chains and binders dragged across the rails, dropped winch bars etc...
Downside of using of hardener are the poly-isocyanates which are a major component. THey are DEADLY. HVLP guns are better than cup siphon types as there is less over spray from the HVLP type. I'm not a nanny state wonk about safety and think that coffee cups should be placarded "CAUTION HOT" but I am very careful around isocyanates. New 3M respirator, long sleeves, gloves, hoodie and scarf as the stuff can be be absorbed through the skin. Doing the job outside is best but has downsides. Ever have to dig a mosquito hawk out of a freshly painted fender or hood?
Catalyzed paints have a fairly short pot life. Only mix what you need. Solvent to paint ratio is more critical than non catalyzed paints. Same for temperature and humidity. Get either of them out of spec and the paint blushes. It is also susceptible to fisheye if there is any silicone in the air or on the surface. FIsheye is easier to fix with non hardened paints.
Prep is the most important part of any paint job. Once you think you have every part levelled and smooth, guide coat it, sand and go over it again..... and again. I don't use tack cloths or solvents for final wipe down. Dawn and water, then wiped down with clean dry cloths and shot as soon as the machine or parts are dry and warmed to ambient temperature. Wet down the floor under the machine if indoors. Same for a large area around it if shooting it outside.
It's harder to nib hardened paints and block out runs. However they really sparkle if color sanded and buffed. .
In short hardened paints are a little more difficult to use but tend to stay brighter longer and are a little more durable than non hardened paints, assuming the prep is good. .
I used plain old Rustoleum smoke gray tinted with black with a few drops of green to match a paint sample from under the air cleaner intake hose. It came out well. I did use an etching primer, paint mixed to spec by volume on a warm dry day. My 2N Came out well. In fact I drove it to a neighbors and back in road gear wide open and the paint stayed on. Bounced it across a field full of gopher mounds with the same result. It's been rained on pretty hard a few weeks ago and the paint is still on. Was good enough for me. New owner hasn't complained about the finish either. It wasn't a '32 16 cyl Cadillac Dual cowl phaeton show car.
I realize others may do it differently and have varying opinions, but the above methods have worked well for me over the years.