BMW 320i Restoration Project - Part 4 - Re-install Windows and Attack Trunk Rust

Jesse from Auto Glass Specialist returned three days after painting the tracks to reinstall the front and back glass. Both glass pieces were reinstalled beautifully, along with new chrome molding strips and fully cleaned gaskets. Let’s talk about those gaskets for a moment.

Cleaning the Window Gasket Seals.

Upon pulling the rubber seals during the glass removal, we, of course, discovered that the tracks were caked in rust, and so were the undersides of the gaskets. The gaskets also had sealant adhesive residue leftover from the original installation, and the outside of the rubber had the typical oxidation due to weathering. The rubber oxidation is the black residue that comes off of rubber seals upon cleaning or wiping with a towel.

To clean these, I coiled them into an Autofiber five-gallon bucket and immersed them in a solution of water with a couple of cups of American Detailer F-bomb Multi-purpose Cleaner Concentrate. They were allowed to soak for several days. Leaning over the bucket, I scrubbed one section at a time with a P&S Yellow Scuff Pad, re-immersing each scrubbed section back into the solution-filled bucket.

Once the entire gasket had been scrubbed clean, I pulled it out of the cleaning solution and immersed it in another five-gallon bucket filled with only water, and let them sit for a while to static rinse.

The fully cleaned and dried rubber gaskets, along with the new chrome insert, made for the final glass re-installation into the freshly painted tracks to result in a stunning improvement to the original appearance.

Trunk Rust Attack!

The next major task was to clean up the rust in the trunk. The steps in this process were very similar to cleaning up the rust in the window tracks, although the trunk rust was far less serious. The trunk rust probably resulted from the sporadic dripping of water through tiny breaks in the original trunk seal—hardly the same as the rust resulting from the thousands of times water probably leaked under the window seals and sat there for days on end. In fact, I remember a distinct damp and moldy odor upon opening the trunk during the initial delivery and inspection of the car.

1. General Cleaning. There was some mold, dust, and grimy deposits throughout the trunk, especially up into the corners and recesses. I figured it would be better to fully clean these before getting into any painting, even if those areas were not to be repainted. At first, I thought about just blasting the inside the trunk with a pressure washer to clean all the nooks and crannies. I decided against this approach, however, because it would be difficult to reach all the deep recesses to fully dry them. Also, it was not really important to clean surfaces that cannot be seen. So, instead, I simply misted everything down with P&S Enviro-clean and agitated with a selection of scrubbing devices, including a Scrub Ninja Star and General Car Care Detail Brushes. Then I wiped away the remaining residue with several Mr. Everything towels. 
2. Solvent Degreasing. To make sure the rust converter, primers, and paint adhere correctly to the surface, I used RUPES Reveal Strong surface cleaner with a disposable blue shop towels. Reveal Strong is a very powerful product that can effectively remove even the most durable adhesives from the paint. It is important to do this before grinding and sanding off the loose rust, otherwise those activities would essentially grind contaminants into the area, causing poor adhesion of the painting products.
3. Remove Loose Rust. Using the same grinding wheel kit with a cordless drill, I started grinding away at the rust spots. It became immediately apparent that, unlike the window tracks, the rust here was much less severe. In fact, most of the visible rust was simply rusty residue that had spread onto the surrounding intact paint from very small rust spots. I switched from grinding to sanding, and the rust removal went much faster. 

The sanding system consisted of a RUPES Mini Ibrid 3” random-orbit polisher outfitted with a 3” Kovax 320-grit sanding disc on a RUPES 3” Foam Interface Pad. The interface pad allows the sanding disc to contact more of the uneven trunk floor surfaces. I ran the machine on speed 1-2, and the sanding took only a short time to complete. [3657: sanding off the remaining rust] The loose sanding and grinding debris were then removed with a vacuum outfitted with a duster brush attachment.

4. Final Scuffing and Cleaning. Then I went over the entire area that was to be painted with a 3M Scotch Brite Medium Scuff Pad to make sure that any spots where paint was to be applied were rough enough for the primer and paint to “bite” into the existing surface. A final mist and wipe with RUPES Reveal Strong and blue Shop Towels made everything ready.
5. Apply Rust Converter. Using an Autofiber Saver Thin Pad, I applied the two coats of rust converter to all the areas that had originally shown rust. Per manufacturer’s recommendation, this was then allowed to cure for at least 24 hours. [3659: Applying rust converter.]
6. Masking. Since the trunk is sort of a naturally enclosed area, I found it unnecessary to do any masking before painting, especially since the areas to be painted were all at the bottom of the trunk. Plus, I am using a spot-blending gun to paint, so the overspray is minimal.
7. Prime. Using the same high-quality primer as was used on the window tracks, I misted the black rust converted spots with several coats of primer. The primer was allowed to set up overnight.
8. Scuff the Dried Primer Surface. Since the trunk area painting did not require precision blending of the paint layers, it was not necessary to sand the primer surface to perfection. Instead, I simply used another 3M Scotch Brite Medium Scuff Pad, lubricated with distilled water. The residue from the scuffing was wiped away with blue Shop Towels. [3696: primed, scuffed, wiped, and ready for basecoat]
9. Spray Basecoat. Next, the primed areas were covered with “Safari Beige” color using the same Sherwin-Williams Automotive Sunfire basecoat. The basecoat was allowed to set up for at least 24 hours.
10. Spray Clearcoat. The basecoat layer was topped with the same Speedokote Euro Clear Low 2.1 VOC 2K Urethane clearcoat. No blending was necessary, again, because we’re painting inside the trunk, not on flat exterior highly visible panels. I purposely built up several layers of clear to increase durability.

Stay tuned for Part 5!