Story From Robert Geddes

Browning Damascus Barrels
By Robert Geddes

With a mortgage and a car to pay for, a young family and a teacher’s wage, I can’t play the really-good-original-condition game in the vintage British gun collecting field.  My eye is drawn to things with hammers and Damascus barrels, but with “the tastes of a viscount on the means of a vicar” some of my guns are somewhere between “worn” and “project”.

The trouble is I haven’t generally had the time, tools or knowledge to resurrect the projects… However, with a big block of time and some spare cash up my sleeve after a bit of a working holiday, I decided to tackle some projects.  Rightly or wrongly, I chose to have a go at browning some Damascus barrelled guns I had with externally worn, faded, stained tubes.

Browning, simply, is a process of controlled rusting and etching which brings out the contrast between the pattern welded steel and iron in a Damascus barrel and protects it further against rust; in practice, though, browning barrels is a slow and careful mixture of (black) art and science.I only got through year 11 chemistry, that not very well, and it was half my lifetime ago.  I remember words like “anode”, “cathode”, “electroplating”, “ion” etc, butI really couldn’t say with any certainty what is happening chemically.  I just loosely followed others methods, and it worked for me!

Before browning

I started by importing some browning solution from Peter Dyson and Sons in the UK (reputed to be made to an old WW Greener formula), and reading about various people’s methods, including the late Oscar Gaddy in the Double Gun Journal (Vol.8, Iss. 2&3, 1997), the late Tony Treadwell’s “An English Gun-Making Heritage: vintage English shotguns and their restoration” and others on the doublegun forum, as well as the method suggested on the bottle I’d bought.  I probably should have experimented on some segments of scrap barrels first; I chose instead to jump in the deep end with a c.1880 W&C Scott 10g single barrel hammer gun which was solid and sound, but cosmetically ugly, with a stained, scratched, rubbed and blotched barrel finish over a barely discernable plain three-iron twist.

I sanded back with 180grit wet and dry paper over the entire barrel surface.  Once the barrel had been scrubbed shiny, it was possible to easily see pits and scratches, and these I carefully filed down with a flat file; thankfully there were no dents (that’s a learning curve for one of the other barrel sets!).  I was not concerned with filing too much metal away and rendering the barrel too thin, for being a single barrel, it was made with very heavy walls (1/4” around the breech!).

Once draw filed I continued to polish down to progressively finer grades of paper until finishing at 600 grit.  I found a dowel plugged into the chamber as a handle useful to hold the barrel in a vise without damaging it while I worked on it, and that dowel stayed there for the whole process as a useful handle.

After finishing with 600 grit

After the mechanical process of polishing the metal, the next step was to plug the barrel and mask off the working surfaces on the lumps and breech face (paint, varnish etc works for this) in preparation for the chemical steps.

Once I was happy with the surface and other preparation, it needed to be degreased.  For this I simply rubbed it down with a clean rag dipped in acetone.

The chemical processes were next: the whole lot went into a roughly 5% weight for weight copper sulphate solution for about half an hour.  CuSO4 is found as “bluestone” in the garden chemical section in some larger hardware stores.  The bath I made from a metre-long piece of 90mm PVC pipe with a capped end.  This solution left a thick, brown sludge on the metal.  Wiped off and then scrubbed down with steel wool and clean water, the shiny bright metal had changed and was a dull grey with the pattern already starting to clearly show through.
After yet another degrease (for any finger marks will prevent the solutions from working correctly and leave blemishes; gloves help, too, and should be worn with most of these chemicals), I wiped the whole surface with a thin, even coat of the browning solution with a clean rag – enough to wet the surface, but not so much that it would bead.  It was then left in the shed to rust overnight.

The next day a thin layer of fine brown rust had formed.  This I scrubbed back with water and steel wool, degreased, and repeated.

After 6-8 cycles of rust, scrub, degrease, scrub etc., the finish gradually darkened until it appeared not to be changing, so I judged it time to stop.  After a final scrub with steel wool and water, and a rub with acetone, I dunked the barrel for about half an hour in a sodium bicarbonate bath to neutralise and halt rusting, then dried it off, and rubbed with a thin coat of linseed oil to highlight and protect.

Copper Sulphate bath

Copper Sulphate scrubbed off

After first rusting

Up until that moment, I was worried the finish didn’t look particularly dark, deep or rich, but the oil brought the pattern out nicely.The pattern itself is quite plain and unremarkable, and doesn’t lend itself to  good contrast (some actual crolle pattern Damascus barrels come next…), but it’s possible to see very clearly the three segments the tube was made from: a circumferential line just ahead of the forend tip where the patterns differ where one long, thin tube on the muzzle end was butt-welded onto the rest of the tube; and a different colouring where a second riband was joined onto the thick breech; the end of the barrel address runs through that join.  Curiously, in bright light, golden flecks catch the light in the muzzle segment; I’m unsure if they might be from my insufficient scrubbing of copper plating or from “greys” from the original forging, but they aren’t in the breech segments, so I believe may be from the way that section of metal took the finish.

Now that I’ve done one barrel, there’s a few different methods and conditions I’ll try to achieve next time. Ambient humidity apparently needs to be high for the deepest, richest browns, hence some people’s use of cabinets with artificial heat and moisture sources (I just had it sitting in my cellar/shed during summer – probably too cool and dry an environment for best results).  The copper sulphate solution has been called a waste of time – even problematic – by others who’ve browned barrels; others have suggested ferric chloride instead; some etch-bath between each rusting, too, but I didn’t.  Preparation of the metal surface is critical, and any pits or blemishes can look unsightly if left (although very small marks do hide in the pattern); there is some metal on the breech end I could have hit harder.  While some advocate a very fine grit, mirror surface, others contend that the rusting action renders much finer than about 320 grit a waste of time.

The end result

A couple of people have seen my results and said “I have this old Bonehill/Hollis etc…(!)”, but I’ll have a go at a couple more of my own to make sure I’ve got it right before ruining the patina on someone else’s guns!

Robert Geddes