For the past two months or so, I've been posting almost exclusively over in Part 13. "Exterior, Skin & Openings".
Like the "Galley & Greatroom" or "Structure & New Wood" before this, there's been a lot of work to do, and then share.
But today (and tomorrow), while still discussing issues related to the exterior aluminum work, I'm getting into some topics dealing with the finish, so I figured I'd come back here and "reactivate" this thread, so to speak.
When I started sanding the aluminum sheet-metal, it was a combination of "by-hand" and using a little Black and Decker Cyclone with hook & loop paper that DW bought many years ago for a furniture refinish project. I test drove it once and wasn't all that impressed, so kind of went back to by-hand, bench sander and belt sander and wire brush for my paint and finish prep - mostly soft wood and around the home projects.
But after trying to get the non-OEM finish on Lil' Queeny scuffed by hand, I soon realized, especially with my aging arms (and that chronic shoulder thing - some of you know what I mean), that just wasn't going to cut it.
So I tried her little unit again, and it actually worked pretty good. I sanded on the bench, I sanded on the floor, you remember (over in Exterior in January). But after getting the metal on the camper frame, it was very apparent that the sanding had only just begun. There was much more to do.
Wally World sold the paper (for the B&D Cyclone) in 5 sheet 80 grit packs and 1 sheet 80, 2 sheet each 150 and 220 packs, at around $4 a pack. That was ridiculous and was going to add up fast!
So over at one home center I went down the sanding tool aisle to see what I could learn.
From a strictly economic standpoint, the best way to buy paper is in the full sheet packs. The stick on, the hook & loop, that sort of stuff, is great for a small jobs, but is cost-prohibitive for jobs that are going to go through a lot of paper.
And it's hard to cut full sheets into circles for a disc type sander without waste, what with being the sometimes mathematician that I am, it made sense, something about eating Pi.
What else? Well you know the tool shelf had quite a selection of these little electric units called "1/4 Sheet Sanders". I figured that meant you could tear normal size sheets into quarters and those would fit the sander, but I wasn't certain. That would be an assumption, and you know what that does. So I delved deeper. Sure enough, that's what it meant!
I looked at pricing (including packs already sold in quarter sheet size), and to quote a great man, "I put two and two together, and added twelve and carried five; come up with twenty-two thousand telephone poles an hour". Yup - cost effective, even if I had to buy a new sander.
I didn't want the most expensive, nor any of the cheapest. I looked close at the mid-range units and settled on this little Porter Cable with the dust bag attachment (same brand as my large pneumatic finish-nailer, purchased a long time ago for our first hard-wood floor - it's been a real dependable guy).
At the same time I got this 25 pack of 220 grit paper for my finish sanding needs (I was yet to be introduced to the whole peeling paint thing talked about over in Part 13.).
Now sandpaper is sandpaper is sandpaper right? Wrong! I know, that's what I thought too!
While getting that metal bending brake over at Harbor Freight the other day, I picked up some paper in various grits because I knew the home supply was getting low. And now I broke it out and gave it a whirl on the sander. Besides it was red! It MUST be better than that General Purpose 3M stuff right? Red for metal maybe? (You know how that whole do-it-yourselfer mind works).
It sucked! It was only then that I started reading the labels closer. I found both types were aluminum oxide, supposed to be an excellent cutting grit. I did some Internet searches to see what I was SUPPOSED to be using. Well, maybe not the best professional choice, but general purpose would work.
I don't know where the red stuff is made, but I got it at HF so that should be a clue. The 3M on the other hand is made in Canada (hello brothers to the north!). And the Performax Brand (a Menard's Home Center brand I think), which is what that 1/4 sheet pack is, was ALSO a good performer, and it says that it's made in USA.
Not only did the HF Warrior stuff break down and not cut well after about 15 seconds, the paper tore up terribly fast. This picture shows two destroyed sheets compared to one sheet of 3M on the sander. The 3M sheet shown did about three times as much surface area to get to its present condition as did those 2 pieces of red Warrior! And it did the area better.
This window opening is where I used the poor quality red stuff - two sheets, and notice the dark grey residue (aluminum?).
The better 3M did this window and the whole wall area of the cab over.
And that was the heavy 60 grit! What would become of the 150 and 220?
Now at this stage of the game I was still learning (well - I'm STILL learning; that's kind of an on-going thing, but I learned some stuff I know now that I didn't know then). For do-it-yourselfers, we often don't know what we don't know as MUCH as knowing what is known, or can be known, but that we don't know! And of course, that all depends on what the definition of is, is.
Like - maybe 60 grit is too course and 80-100 would have been the best to start with. That's because too deep of a scratch requires more material removal to smooth it down for the finish sanding. More work, more material removed - you get the idea. But by the same token, while speaking with a professional, I probably shouldn't worry too much about the metal thickness being adversely affected, and I DID have those heavy layers of non-OEM bright white paint to work with, its peeling where bent over, etc.
And another thing I'll share with you (be careful with how you use this information, as you don't necessarily want it getting into the wrong hands). While watching a YouTube video of a professional painter painting aluminum, he said to get about a 180 to 220 scratch.
And we can use that - I mean if we want to sound like we know what we're talking about. You can throw that around at the water cooler and probably come off pretty cool!
"Yeah, I put down a 220 scratch and then washed the surface with (insert prep wipe of your choice here) and then got my first finish coat put on." And you kind of want to say it all non-nonchalantly-like. Hey! If you talk the talk, you can walk the walk! ;)
Tomorrow we'll talk the talk about paint.
