[TheForge] Soldering copper tubing in an AC unit

[Andrew Vida]

On 4/9/2012 7:19 AM, Ron Childers wrote:
> Andy, master of subtlety that you are,

Oh pshaw...

> Boss finally got tired of saving all that money and hired a real HVAC
> man. He is clean, doesn't stink, has a decent service truck and will
> probably have the repairs done in a day. I know he's a genius because he
> agrees with us. Bozo ruined the new reversing valve with too much heat.

Bernie Bernstein, the man who taught me silversmithing, also made the 
point with me about the buy/built decision, citing that most of the time 
buying is the economically wiser choice.  Experience has since taught me 
the sage nature of that particular advice.
>
> You outlined the procedure we use to silver solder guards onto blades-
> just enough heat on the work to make the solder flow into the joint. I
> have heard sticking the blade through a potato makes a good heat sink to
> keep the blade from getting too hot; sounds reasonable, has anyone tried
> this?

Potato sounds good - full of water.  The one thing I would be wary of, 
however, is the staining nature of potato juices.  Potato will put a 
hard and dark oxide layer on the steel, so I would not recommend this 
particular item if there is no further finish work to be done.  Potato 
will stain the steel fairly quickly as I recall and most likely will do 
so more rapidly when the steel gets hot.  I have never tried to blue 
steel with potato, but have only experienced the unwanted staining of 
items that I unwittingly left in contact with them.  No idea whether the 
color would be uniform, but I will note that it is a cold blue, which I 
prefer to the hot blues; less "depth", but also far less "streaking", 
which makes the steel look as if an eight-year-old had at it with a 
spray can.  One thing I recall about this particular blue, however, is 
that it is very gray and businesslike in appearance when lightly 
applied.  Longer exposures resulted in a fairly dark black oxide, though 
not the jet black that cat pee produces.