One of the biggest points of discussion in the Sling community is what primer to use. Since our aircraft are designed using 6061 Aluminum, they don’t actually need to be primed. Technically. Maybe. Maybe not. There isn’t a right or wrong answer. The quick-build planes from the factory come with making surfaces primed. The quick-build planes from other sources may or may not be.
I’m building my plane 150 yards from a brackish lagoon, so if there is a plane that needs to be primed, it’s likely mine. After a few tests, I’ll be using SEM Self-Etching Primer. Here is my process:
- Remove factory plastic protective covering from the part
- Deburr & Dimple as needed
- Initial Assembly to ensure all parts are accounted for and they fit. Disassemble.
- Clean parts using a 1:1 ratio of Simple Green Extreme aircraft cleaner and water. Scrub with a red 3M ScotchBrite pad.
- Using gloves, rinse with clean water and let dry.
- Degrease with SEM Solve. This stuff is nasty, I use a respirator, gloves, Tyvek and spray in my paint booth.
- Wipe dry with microfiber cloth. It should flash off when clean, if it doesn’t flash off, repeat the spray with SEM Solve.
- Hang in paint booth
- Spray with SEM Self-Etching Primer. Use several light coats – normally 2 unless I realize I missed something, then a 3rd one goes on. You want these to be very light coats, you’re not going to cover it with 1. These go on 10-15 minutes apart, and then I let the part dry for 24 hours before final assembly and riveting.