[TheForge] pitted rust

Wed Oct 1 10:58:01 2003

I'm not sure if this will work for you
but I sometimes heat the material and then
use a needle scaler on it
 I use ferric nitrate to rust
----- Original Message -----
From: "Cameron Stoker" <[email protected]>
To: <[email protected]>
Sent: Wednesday, October 01, 2003 7:48 AM
Subject: [TheForge] pitted rust

Hello all,
I have a bit if a problem on a project and thought I should see what
the collective wisdom of the forge might have to offer.

I have a client who would like me to duplicate the rust finish found on
an old piece of ~ 2" pipe.
This guy is very picky and I've tried several textures which have been
rejected.
The difficulty is that this is some serious rust. I think this sample
of pipe was buried in  the ground for many years. Its surface is
covered with small pits maybe 3/23" average diameter and about 1/32
deep. i.e. it's a fairly heavily pitted rusty surface. I am imagining
the corrosion process could develop this way when grains of varying
composition and size sand/minerals of the ground being pressed against
the pipe.

Typically when I do a rust finish, I treat the item with muriatic acid
to remove any black forging oxide and to chemically clean the surface
of oils/junk/etc. I then warm the metal with a small torch and sprits
it with bleach solution. This gets a powdery red oxide almost
instantly. I do several treatments with bleach solution, then switch to
a saline solution and heat for several days. I've found using only the
bleach solution will develop streaks in the patina and it can for white
residues. The salt water keeps the patina even, and has some nice
subtle color variations such as brown and black spots speckling the
surface.

The main fault with my 'artificial' rusting, is that it would take me
years to develop any kind of deep pits on a surface. Someone suggested
packing the pipe in a box of sawdust permeated with muriatic acid, but
this seems like a fire hazard to me, and I bet it would still take
years.

My current best idea is to braze a lot of small diameter ball bearing
balls to a set of die plates and texture the pipe in the hammer before
the rusting.

Anyone have any clever tricks for getting deep rust?

Seems like there should be a way to do this electrochemically, perhaps
using a plastic sponge/foam as an irregular electrode against the pipe.

Thanks for any advice.

Cameron Stoker
[email protected]
"May you run like a vicu�a!"
pgp key @ http://keys.stoker.net

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