Most of this weekend was prepping and painting the engine bay and other parts. I used POR-15 because I've had great luck with it in the past. Correctly prepping for POR-15 is a fussy PITA, though.
The instructions say:
- Make the workpiece free of loose dirt and rust
- Spray with the accompanying degreaser, diluted at least 4:1
- Rinse with water
- Keep wet with the etcher *UN*diluted for at 20-30 minutes depending on condition of workpiece
- Rinse with water
- Wait until "bone dry"
- Paint with POR-15
So when going through all of these steps & processes with the engine bay, cradle mount shells welded into cradle, A/C & heater tubes, fuel tank vent tubes & a set of knuckles... prep takes most of a day.
The etching material is phosphoric acid with zinc in it somehow. It leaves a coating of zinc phosphate on the workpiece, which is supposed to be the best base for POR-15. This works on "any metal" including aluminum and of course ferrous materials. However, it doesn't exactly look pretty before applying the paint. If using black, not a problem. However, I used clear on all the tubes, for S&G's, so we'll see next week how those turned out.
I used a squirt bottle to apply both the degreaser and the etcher. That led to spotty application on the tubes, but those are difficult shapes to deal with. Short of getting a long narrow tray to soak them in, I'm not sure how to do much better, though. They're annoying workpieces to handle.
When applying the degreaser, even after rinsing, I noticed that where the droplets aggregated on the bottom surface of the tube had dark smudges on it. The smudges did not rub off. I put the tubes up against wall and hit them with the degreaser again, but it didn't touch the smudges... so I guess they were ok? Same droplet effect resulted in spottiness of the etch, but that seemed unaffected by the smudges.
The weld-through primer I applied in prep for having the new hinge box welded sticks to bare metal, but apparently does not stick to POR-15. I had to wipe aggressively, but it wiped off the POR-15 adjacent to the metal that had been stripped by the battery acid, while remaining firmly attached to the metal. Interesting. This made it easy to see exactly where I needed to paint... and since weld-through primer is basically a high-zinc coating, it was not affected by the etcher and should be a great base for POR-15, although the surface is a bit rough.
Here are the U-body minivan knuckles that I blasted LAST weekend, that have been sitting around in the back of my diesel WKGC for the last week. They developed a little spot rust, but developed an entire surface full of flash rust when I used the degreaser and then rinsed with water. This stuff better work, as using a bunch of water-based applications on freshly blasted cast iron goes against the foundations of my education as a gearhead.
Here they are after the etching prep:
I did not get a shot after painting, so you'll just have to wait a week.
Here are the A/C tubes... I'm pretty sure this is after etching:
A couple of close ups of my spotty etched surface:
This is definitely after etching... I think this was Sunday morning after doing all the prep Saturday. It may be hard to see in the photo, but the real world color is much whiter than blasted aluminum
Here they are painted:
Close up of the painted surface:
No flash & flash of the engine bay with complete prep, but before painting:
The result (the no-flash is too dark to see anything... as one might expect):
I have a to-do list of a bunch of fiddly stuff to do next weekend, but I'm thinking I can mate the engine and transmission and get the assembly dropped onto the cradle on Labor Day weekend.