aluminum 'welding' Q...

[JWL]

Here are the facts as I see them. And, I say these things after TIG welding thousands of aluminum joints.

If you are not going to do the job yourself, do not follow any advice about how to clean or "Vee" groove or any other preparation step. Leave that for the professional selected to do the job. In most cases the job is made more difficult when the inexperienced "helper" gets involved. I would much rather do the prep the way I want it done.