Priming the exterior of your school bus is a very important step in the conversion process. It will make sure your final paint job stands the test of time. And believe us, you only want to do that exterior paint job once.
We used an industrial grade automotive primer that required application via spray gun. We’re happy we did it this way, because that primer was diamond solid and provided a good rough surface for the exterior paint.
Tools & Materials Required:
- Degreaser (we used Simple Green) and a bucket
- Lots of rags!
- 320, 400, and 600 sand paper (very fine grit!)
- Automotive primer. We went to an automative supplies shop and got their standard industrial grade primer with its catalyst. This was cheaper than buying at Home Depot.
- Lacquer Thinner
- Respirator mask
- Spray gun (check to see if you can rent from Home Depot or Lowe’s)
- Masking tape (in bulk!)
- Newspaper or rolled painter’s paper (again, in bulk!)
- Prep All
- An awesome Italian friend
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Step 1 – Degrease the exterior
- Wait for a sunny day, then try to make a fun time out of completely degreasing the exterior. Lots of soapy water and rags, getting into every nook and cranny and working around every screw and rivet. This is really important, because the primer won’t stick to a dirty surface.
Step 2 – Sand the exterior
- We thought we needed to sand through the yellow paint down to metal. We were wrong. That yellow paint and its underlying primer are rock solid protection for the metal skin of your bus. You don’t want to take that away. Instead you want to remove just the clear coat over the yellow paint, and insodoing provide enough texture for the primer to stick well.
- If you plan to keep your current reflectors, tape over them with masking tape to protect them from your sanding.
- Use 320, 400, and 600 grit sandpaper to very lightly sand the exterior. You want the surface to lose its shine and appear matte. You do not want to wear away the yellow.
- Be very detailed with this. Work to remove the clear coat on and around every rivet and support bar. It’s a royal pain in the —, and we’re really grateful our dear friend Claudia was there with us in the trenches!
Step 3 – Wipe down sanded exterior & prep
- After sanding, the exterior is going to be covered in yellow dust. Wipe this off with rags.
- Wipe the entire exterior with Prep All, making sure to get every nook and cranny.
Step 4 – Tape off the windows
- Use paper and masking tape to tape off:
- The windows
- Blinker lights
- The bus’ current reflective tape
Step 5 – Apply the primer
- Mix the primer, catalyst, and lacquer thinner according to the paint’s instructions (and the instructions of the paint gun, if any).
- Make sure you are wearing a respirator.
- Spray the primer section by section, giving multiple passes until the section is fully covered. It’s helpful to have a friend or two standing farther away who can see spots you missed.
- Wait until the paint is fully dried to remove the tape and paper.
Step 6 – Repeat!
We painted our bus in stages. One full side and back, other full side, front. We did this simply because there wasn’t enough time in the day to do all the prep work for the whole bus and then prime the whole thing. So we did it in stages.