by chuckthebeatertruck » Fri Nov 09, 2018 4:23 pm
I choose my paint based on the bike.
I've sprayed nitrose, lac, acrylics, urethanes, and epoxies. The first two aren't worth your time; but there are many excellent acrylics and urethanes on the market in a variety of forms. I've sprayed bikes, used rattle cans, and have even brushed frames (believe it or not; with the right paint properly thinned and a very good brush -- you can flow a very nice coat of paint on a frame with a brush. The hard part is waiting a month or two to buff it out -- but when you do the result can be every bit as good as a sprayed frame -- but it takes a lot of patience and time)
The only one I steer clear of are aklyd enamels. They work fine; but none are truly UV stable. Colours start to muddy or wash out in the sun after a few years. Clear urethanes don't adhere well to aklyds either; so that's not a solution.
The last 10 bikes or so were all media blasted to bare metal and in the same day sealed in true epoxy primer. I then spray a binding agent, followed by two or three very thin top coats. All the magic happens with the clear coats. I generally do 3-4 medium clear coats of a very high quality urethane. Let it sit 24-48 hours, and then flow coat. The result is a superb depth of gloss and after a week or two -- a finish every bit as hard as powder coating. However, I can easily repair it; buff it out; or even respray sections without much fear.
I have also done two frames in the last 5 years with "rattle cans" -- one set from VHT (chassis and roll bar paint) on a bike I thought I was going to sell right after I finished it and the other from SEM. Both have held up quite well with no issues -- with the 5 year old paint job looking the same as the day I assembled the bike. They look much more "original" than the finish of what I describe above -- complete with a bit of "peel" to the finish.
I don't plug anything -- I use 3M professional painters tape and fine line tape to take care of details.
Do not, under any circumstances, have any type of oil or grease near something you are painting. Any overspray that picks up that oil will deposit very nice fish eyes or solvent bubbles all around the area.
I've no experience with building up layers of powder so I can't comment on that.
To be very honest -- I only spray frames in gloss UNLESS the OEM didn't or there's some other reason. For example, several of my Guzzis came with a dirty, not even quite semi-gloss frame finish. So, I use a 50% gloss or a matte flat (not the hot rod flat stuff -- hate that crap). I've never been overly concerned about covering up casting texture.
The only real challenge to painting a frame is figuring out how to evenly cover all the tubes, top, bottom and sides. Again, I've done it a bunch of ways from saw horses to milk crates to hanging the frame from a tree. Currently, I use two painting racks I made out of gas pipe. The "big" rack is 8 feet tall and 8 feet wide. It can support 200 pounds easily; and I use stainless steel wire to hang the frame. I leave additional wires strategically placed so I can change the position of the frame to get at "hidden" areas. I still miss a spot from time to time and touch them up later.
There are so many ways to do this it's not even funny. Just pick something and go with it. You really can't go too horribly wrong UNLESS you intend this to be a 100% restoration and have it judged as such by an organization like the AMCA.