[TheForge] pitted rust

Wed Oct 1 12:32:00 2003

Just guessing but maybe overheat your steel to make a heavy burnt scale coating (accelerated rust) then do your rust treatment.

Bob
_____

>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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