Continuing the saga of the mid-90's rims, today's post covers damage repairs, and masking. If you haven't read the prior posts that got us this far, the links for the other 3 parts are here: Part 1, Part 2, Part 3. Basically, I got a set of rims, they were kinda beat up, but I'm going to use them anyway because a few hours of my time is worth the $700 I would have to pay for a new set of 15" rims. This is just one more way to express that the journey is the destination, and why incur the environmental cost of new rims when you can keep another set out of the landfill? Everybody wins. If the set you're messing with doesn't need repair, and you don't plan to do any fancy paint, you could skip to the end and shoot a few coats of clear and be done with it.
Filling the Gouges
I could have used "bog" or Bondo, but I had a small tin of Lab Metal from when I swapped out the Westy poptop for a Riviera/ASI top a few years ago. It had dried up a bunch, but a after letting a few ounces of lacquer thinner sit in the tin overnight, it softened it right up. Similar to bog, or spackle the Lab Metal applies like a paste. Work the stuff all the way into the damage. If the Lab Metal won't hold, you may need to dig some material out of the damage so the Lab Metal has something to bite into. It's sort of like how the dentist sometimes has to drill out some good tooth material in order for the filling to set without an air bubble, and then hold.
Either way and whatever material you use, over-fill the damage so there is extra filler all around and on top of the repair. Consider that you will be sanding this down, so don't go crazy with it, but if you try to make it all nice and flush when it is wet, the material will shrink as it dries so you'll have a concave patch relative to the size of what you filled. Once it is dry, lightly sand with a high-grit paper (like 220 or something) until it is flush with the surrounding undamaged wheel. I followed this step with a general light sand with 320-grit paper on the entire rim and then cleaned it with glass cleaner so there was no dust remaining.
Masking and Cutting
But, it can be done. First, use tape like a tack-cloth, pulling the surface dust off the raw aluminum. Doing this immediately before you tape will definitely help the tape stick. I also found that over-taping, or applying tape beyond the edge of where I wanted the paint to be allowed me to direct the tape better. Once on, I would set the edge with a razor-blade held mostly parallel to the rim but at a fixed angle, sliding along the rounded edge. This defined a very clear and consistent edge that I couldn't do with just the tape-edge. Each transition from taped to not-taped where I could get a razor-blade I defined this way. Yes, this takes considerable time. For those areas where cutting the line with a blade wasn't possible, I followed the old axiom from when I painted houses: use tape to prevent paint from getting where you don't want it. More simply, if you can't get the tape right on the edge, err on the side of getting a little paint where you don't want it versus covering up where you really wanted it in the first place. This sounds obvious, but in practice we all are such perfectionists that we try to get the tape right on the line. Sometimes, this means you cover up a thin line where you wanted paint and you don't see it until you pull the tape. That moment really sucks. So, get that paint a little too far onto the raw aluminum and then work the line afterwards with a razor. This is much easier and looks way better than trying to do touchup or retaping/shooting. Between the sanding and the taping, this is where you spend 95% of your time and makes the difference between a not-that-great paint job and a looks-pretty-good one. It's all in the prep.
I can't believe how long this has gotten or how long it has taken to finish these rims. Anyway, I should be finishing this thread of posts with one more: next time with priming, color, wet-sanding and clear-coat. Thanks, as always, for following along.