Rust resistance of blackened mild vs regular stainless?

Tibbie Croser · Post by **Tibbie Croser** » Sat Nov 14, 2009 8:42 pm

Does blackened mild steel have as much rust resistance as nonblackened stainless steel? Does rust resistance vary with the blackening method? What's the closest modern equivalent to the techniques used for blackening munitions armor in the 16th century?

(I ask because I'm thinking of factors involved in commissioning an SCA rapier helmet that would resemble 16th-century munitions pieces, blackened and left rough from the hammer.)

Cet · Post by **Cet** » Sun Nov 15, 2009 12:28 am

Does blackened mild steel have as much rust resistance as nonblackened stainless steel?

Not even close.

oes rust resistance vary with the blackening method?

yes but barring plating even the best doesn't coem close to stainless.

What's the closest modern equivalent to the techniques used for blackening munitions armor in the 16th century?

There was not a universal approach to blackening in period; forge black, heat bluing, russeting, oil blackening and painting can all be documented.

For the look you want the best choice for an SCA application would be blackened stainless.

Thomas of Monmouth · Post by **Thomas of Monmouth** » Sun Nov 15, 2009 5:36 am

Hi Flittie

I have some mild and spring steel items that have been blackened with linseed oil and they don't rust at all. Only in places that have been left as white for decoration or in the parts that routinely scrape across one-another in use, where the black surface has been worn back to steel, is there any possibility of rust (but of course, anywhere that the black has been worn away by the movement of the plates also tends to be self polishing for the same reason).

Oswaldamar · Post by **Oswaldamar** » Sun Nov 15, 2009 6:10 pm

I have used a combination of linseed oil and beeswax on a lot of my blacksmithed projects. Keep rust off like a charm.

Tibbie Croser · Post by **Tibbie Croser** » Sun Nov 15, 2009 8:51 pm

Point taken about the superiority of stainless for rust resistance. In which case, how does blackened mild steel compare to untreated mild steel for rust resistance?

(Cost is more important to me than rust resistance; I have to take care of my steel rapier, dagger, and buckler anyway. Stainless is so much more expensive as a raw material and in terms of an armorer's shop time.)

Baron Alcyoneus · Post by **Baron Alcyoneus** » Sun Nov 15, 2009 9:03 pm

Blackening is essentially a process (which can vary) of controlled oxidation. You are oxidizing it, but making the maintenance easier.

Cet · Post by **Cet** » Sun Nov 15, 2009 11:11 pm

Cost is more important to me than rust resistance; I have to take care of my steel rapier, dagger, and buckler anyway. Stainless is so much more expensive as a raw material and in terms of an armorer's shop time.)

There are pros and cons to all the various methods. The simplest and cheapest process would be simply painting it black with Rustoleum or similar oil base paint formulated for metal.

Thomas of Monmouth · Post by **Thomas of Monmouth** » Mon Nov 16, 2009 4:56 am

I would definitely recommend against using black metal paint. I used Hammerite oil based metal paint on my gauntlets and it chips off so easily that after about a dozen times using the gauntlets only about half the surface is now covered in (chipped) paint. The rest is beginning to rust and of course you cant scrub at the rust without removing more paint. Also it was thick, streaky and glossy.

Not really a good look.