Yah, yah, you've made it clear. We're just noodling on options, trying to help.....and the holes would be useful.
It's been more than 30 years, but I did quite a bit of experimenting with the...uh...aluminum soldering/low temp...??...welding, but want to be sure we're on the same page with it.
I was at a boat show in Spokane in '83 and watched a demo where a guy punched a hole in a beer can, then used a propane torch (don't use Mapp gas - something about the oxygen) to heat it up and smear the stick onto it. It melted fine and bridged the gap fine; it flowed fine and feather edged and if it'd been regular solder, I'd've said it was a good joint.
He took an ice pick and really punched that "weld" and it was hard as rock and there was no peeling of the weld. Ice pick didn't touch it. Then he "welded" 2 pieces of aluminum together and same thing. I was mightily impressed and bought a batch of it.....and it worked extremely well for me, too.
The rest of the story: I was self-learning the appliance and refrigeration business at the time in a small, backwoods town in the mountains of north Idaho and a very common complaint was where people's refrigerator freezers had iced up and they'd used knives to chip the ice out. Of course, with those old stamped evaporators, they punched holes in them and all the freon escaped. How to fix ??
I tried the green "epoxy" sticks that you melt on and a couple of other things, but nothing would stick well enuf under that pressure in that environment. The aluminum solder sticks seemed a good bet.
There's a coating on the aluminum that I had to sand off, then used a solvent to clean oil off it and soldered it up. It worked wonderfully well, looked great (I'm well aware of what a cold solder joint looks like) and I went ahead and charged it up.
Next day, the people called me back - no cooling. Long story a bit shorter, careful experimenting showed me that the stuff is porous. Looked very good, but pressurize the system and put soap solution on it and you could see it foaming. Never did find a cure that really worked and we threw a lot of old refers away.
OK, I know that Gore-Tex works by letting air molecules thru but blocks the larger water molecules. (in my experience, Gore-Tex doesn't work very well, but anyway....it's a good theory) Will this stuff be the same ?? I dunno - never tried that, cause it made none in my application and I was very busy, but I tend to think it "would" block water. Under pressure, as in underwater ?? Again, I dunno. It would be worth experimenting with, cause the stuff makes an extremely strong bond and is rock solid - much stronger than the aluminum.
It's easy to see when you've got the heat right. Melt the stick on and it beads/balls up - round edge. Heat it some more and it flows out very nicely. Heat it too much and the aluminum melts.
