Doug Goncz wrote:
Hello, metalworkers!

Hi Doug!
(Snip)

Can presooting aluminum, torching it to remove the soot, and applying flux with
the tip of a solder wire, then rubbing with solder wire be a way of tinning
aluminum for soldering?

The way that I misunderstand the process is as follows:

* Use an uncontaminated (by other than aluminum) stainless steel brush to knock
off the thickest part of the surface oxide of both pieces to be joined.

* Clamp the pieces in place and cover them as much as possible with a
thermal isolating blanket. (Kaowool)

* Heat the bejeezus out of the pieces until tin solder flows.

* As you add to the puddle, use the stainless brush in your third hand to scratch
the aluminum oxide off the surface under the puddle.

* Keep scratching for the entire length of the joint. The solder will act to isolate
the new surface from oxygen. New oxides will not form.

* Let the workpiece cool. Be careful that the pieces not move during the critical
liquid - plastic - solid phases.

I have never used this process but it seems reasonable. A bright fella such as
yourself will probably want to build an argon chamber to further limit oxide formation.

Let us know how it goes OK?

--Winston