Gun metal grey

[hortonstn]

How do I achieve a gun metal grey finish that is tough and will last without having to touch it up
Often?
Thanks

[Justin Urbantas]

I use Birchwood Casey cold blue, and then cover with naval jelly for 5 min. Rub with a fine steel wool, then rinse in water, dry and oil. Looks like this.




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[TommyG]

Recently I posted a moravian fowler, on that piece I did 6 coats of LMF brown.  1 coat in the morning - card off with denim 4 hrs later, then apply another coat and scuff that off after 4 hrs with a maroon scotchbrite.  Repeat for 3 days=6 coats, scuff the final coat with marron then gray scotchbrite.  Neutalize with baking soda paste and hot water, heat the barrel to dry and coat with oil for a few days.  After that wipe w/ acetone an apply 3 coats of wax.  For a more even gray, I LMF brown 3 coats, scuff between with maroon scotchbrite.  I just want to get the rust to "bite".  Neutralize & dry.  Wipe w/ acetone & apply a coat of Oxpho blue then rub back with 4-0 steel wool and wax.  I've found that (for me anyway) that acetone works best.  Tried it with DA and had some flash rust afterward.

This gun was done with LMF & Oxpho blue


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[hortonstn]

Justin
What does the navel jelly do?

[Justin Urbantas]

Justin
What does the navel jelly do?

Removes the blue and leaves grey behind

[fahnenschmied]

To put things in a flintlock era perspective, "Gun metal" is bronze, as in artillery tubes and while bronze can be chemically tarnished to a grey color, in the  18th and 19th century it meant a bronze color.   I don't know what such a finish would have been called in the period.

[Eric Krewson]

I love the look of gray but for me it is not durable, the two that I have grayed both have shiny butt plates where the gray wore off in short order.

[wmrike]

For bright steel, a good soak in phosphoric acid (available either at or through your hardware store) will leave a slightly dull, light gray finish that is reasonably rust resistant.  It is a watered-down version of the familiar Parkerizing process.


I have applied this same process to rusted (i.e., browned) surfaces.  I vigorously scrub the piece with steel wool soaked in phosphoric acid so as to remove as much rust as possible, wipe off the garf, wipe it down with acid, and let it set for a day before rinsing and oiling.  This produces a noticeably darker finish that might be, by my casual estimation, more rust resistant than a simple acid treatment on bright steel.

[G_T]

A few weeks back I boiled lock parts in a dilute solution of phosphoric acid until they were dark grey, then rubbed them back with scotchbrite, then oiled. The appearance is sort of like pewter, and the surface seems slicker than raw steel would be. Whether it is durable or not I have no idea at this time. I figured if it was not, then I'd do the same thing with rust bluing and rub it back again.

Gerald

[alex e.]

On a gun that will be used,all finishes,in my experience,  are temporary.

[rick/pa]

Does Naval Jelly contain phosphoric acid?

[Dennis Glazener]

Goggle is your friend:

Naval Jelly does contain Phosphoric Acid (10 to 30 percent by composition) and minute amounts of Sulfuric Acid (0.1 to 1.0 percent by composition), as well as other hazardous chemicals—Phosphate ester (1 to 5 percent), Polysaccharide (1 to 5 percent), and Isopropyl alcohol (1 to 5 percent)
Dennis

[rick/pa]

Goggle is your friend:

Dennis

Thanks, Dennis.  I keep forgetting the world is at my fingertips with the internet.    I'm guessing that Naval Jelly alone would produce a grey finish since it would etch the metal.  Does this sound right?

[bgf]

Naval jelly should work.  I restored a couple of rusty scythe blades and it gave them a grey frosted appearance, but I painted with black enamel (which is period correct for that type of thing) so don't know if it lasts well.  Also you can blacken with a cold blue and then rub back with green pad and oil.  I agree that it isn't durable -- you'll get fine rust and eventually end up with brown (which is pretty nice and very durable in a few years of maintaining.

Probably the easiest way is to degrease and soak in vinegar, but probably no more durable...

[wmrike]

Cold blue keeps getting dragged into the conversation.  Years ago I worked in a life-test lab and one of the things we looked at was a way to inexpensively coat the parts we were manufacturing.  Various cold blues were tried and they were all deemed rust magnets.

Brownells' Oxpho blue may be the exception.  I believe it is a variation of the phosphate theme.  I have found it to be very durable, though not the prettiest.

[alyce-james]

rick/pa; Sir. Naval Jelly will work just fine, then adjust color to your liking. Good luck. Aj.

[rick/pa]

rick/pa; Sir. Naval Jelly will work just fine, then adjust color to your liking. Good luck. Aj.

Thank you AJ.  I have the parts for my next gun but since we are looking for another house it might be some time before I start.  I will keep your advice in mind.

[Mark Elliott]

If you have any worries about Naval Jelly,  I use cold blue followed by tincture of iodine.    The tincture of iodine is an oxidizer.   I generally leave the part overnight before I scrub back.   It can get rather nasty looking overnight.   I have found the best results are achieved by a good even blue which requires a good de-greasing first.   I scrub back with green then light gray ScotchBrite pads.    This approach results in lots of small black pits that gives you the gray.  It is more an aged look than a coloration and can be spotty if you don't get a good even blue to start.   You can take off too much with the green pad, but if you do, just repeat the process. 

[rick/pa]

I recall reading one time that if you want to make sure a screw never comes loose, dip it in iodine before putting it in place.  The screw will rust tighter than a bull's arse in fly season.  That's a mighty powerful oxidizer. 
That would account for the minor pits on the metal surface I reckon.