doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Rust bluing tech question

I'm rebluing the barrels of an Iver Johnson Hercules, which came to me pitted/rusty on the exterior (bores are perfect), and bearing the marks of a previous owner's attempts to sand it clean. After striking them, and working down through the grits to 400x (getting rid of 99% of the corruption in the process), I started the rust bluing cycles and am about halfway there- it's looking great after only three rustings. What concerns me are the traces of shiny soft solder exposed in the joints of both the top and bottom ribs. Not egregious, but noticeable in a couple spots an inch or so long. Short of going back to the abrasives at this point, is there a trick that I can use to camouflage them? I realize it is a low/mid-level gun and perhaps it looked this way from the factory 80 years ago and I shouldn't trouble myself over it, but still...

You can use a Magic Marker or equivalent pen with solvent-based ink and an ultra-fine tip. Do it before you oil the barrels.

http://www.brownells.com/gunsmith-tools-...-prod25494.aspx

Solder blacking solution.

I hope no one gets their panties in a wad,but the way my German gunsmith buddy addressed residual solder( very-very hard to see against polished steel) was to drop the barrels into hot salts tank for exactly 14 min.,not a second longer.Then he finished with rust blue.
Mike

Why wouldn't he just use some cold blue to see what changes color (steel) and what doesn't (solder)?

Chuck H
That's what I do for soldered on sight bases,but I don't remember ever seeing any cold blue in his shop during the six years I was in and out of it. He used heat blue for screw heads,pins,etc.
Mike

Soft solder will turn dark gray on it's own with some time. They were most probably done with 50/50 or 60/40.
The new lead free solders will stay nice and white bright forever for you though. One reason I don't care for them on rib work.

If the problem areas are those thin lines of solder that appear as gap fillers between the rib and bbl where the fit of the parts was less than optimum,,the above will take care of the problem pretty well for you.

A touch of some cold blues will darken them too.
Brownells Oxpho blue will darken lead soft solder some. Enough to take the stark contrast of the line away.
A tooth pick with the end hammered lightly to create a brush or wick effect is handy to apply the tiny amount to the area. Plus the Oxpho blue doesn't 'after rust' like many cold blue will unless you flush them off w/water.

If the problem is patches of excess solder from the tinning operation originally done that are still visible on the tubes & ribs where they meet. I'd go in and remove them now.

You don't have to polish the entire set of bbls back down, just do those small areas and keep going with the rust blue. The color will match back up in a couple of coats.

Metal scrapers are good to clean out the tight area between the rib(s) and bbl.
Quicker and much more efficient than using a file or abrasive paper.

Using a V shape scraper with light hand pressure you can get the point right into the solder joint. Then rolling it to either side, clean the bbl or rib edge off w/no added work needed.

Thank you, gentlemen!