"Michael A. Terrell" wrote:

GeoLane at PTD dot NET wrote:

On Wed, 13 Jul 2011 21:44:55 -0500, Ignoramus23641
wrote:

I am trying to solder a brass fitting to the fuel tank.


Anyway, the tank, while not exploding, just does not, flat out, accept
solder. The solder just balls on top of the steel, does NOT wet it at
all, and rolls away when exposed to the gases from the propane torch.

I tried a couple of fluxes and nothing helps.

i

You've already accomplished what you wanted to do, but I'll mention
that I've experienced this before too. What has worked on one or two
occasions was to scratch the solder into the steel with a screwdriver,
coarse steel wool, sandpaper or the tip of the soldering iron while
all was still fluid. That made the solder stick to the steel,
"tinning" the steel first. The flux that I use is made by Kester and
is a pink liquid. I bought it at a yard sale years ago. I have no
idea if it's still available.

It's called, 'Ruby Fluid', and was sold for copper plumbing:

http://rubyfluidflux.com/uploads/New_Rubyfluid_Flux_Product_Sheet_with_THEIR_images _2.pdf

http://i53.tinypic.com/2myoshe.jpg

Kester has dropped all pluming solders & fluxes from their website,
but that was a common product. It's harder to find these days, since
they switched to lead free solder on water lines, but some stores still
sell small botles of it for under $5.


http://www.amazon.com/Ruby-Chemical-1PT-Liquid-Rubyfluid/dp/B000CNMHJW/ref=pd_cp_hi_0
$5.81 for a pint.

--
It's easy to think outside the box, when you have a cutting torch.