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Stainless issues. [message #8436] Sat, 19 December 2009 23:34 UTC Go to next message
avatar derekh  is currently offline derekh
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Okay so I ordered my ring in stainless, polished it down to remove all the pitting. I wear it, thinking that since it is stainless, it should be good to go. Not sure what type of stainless it is, but it isn't the kind that doesn't rust. And, stupid me, I learned that the bronze binding agent, that leaves marks too.

So I wear my ring for awhile, it leaves a slight dark ring around my finger. Not a big deal in and of itself, but then notice that after wearing my ring all day, I have not only a nice dark ring around my finger, but the edges are rusted.

Is there anything in the works to produce a metal material that isn't going to leave a mark or rust? I know it was my fault I didn't really think too much about the repercussions of the materials (at least the bronze) but I figured the stainless wouldn't be the kind that rusts.

What up?

Derek
Re: Stainless issues. [message #8437 is a reply to message #8436 ] Sun, 20 December 2009 00:34 UTC Go to previous messageGo to next message
avatar dadrummond  is currently offline dadrummond
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I sympathize - my ring, which I wear daily, also leaves a dark ring, although only on the underside of my finger. I've also been thinking about my prints as if they were rustproof. Have done some research on that.

Two things for others who are thinking about stainless steel + bronze jewelry.

First, neither stainless steel nor bronze are rust-proof, despite popular notions to the contrary. There is no such thing as a "type of stainless that doesn't rust". It is "stain less", not "stain proof". Bronze also has excellent, but not perfect, corrosion-resistance. If you want oxidization-proof jewelry, use a virtually oxidation-proof material such as gold or platinum. Shapeways -- give us gold or platinum! (Or at least wax, so we can cast in such a metal...)

Second, corrosion is strongly influenced by body and environmental chemistry. Sweaty hands are the primary reason for corrosion. Some people have sweaty hands (like me), causing jewelry to corrode more quickly. Some people have body chemistry so extreme that they cannot wear leather watchbands, which simply dissolve when worn repeatedly. Others have no problems at all.

So: the stainless/bronze amalgamation SW produces will rust. I recently ordered a piece from Bathsheba that is produced by virtually the same printing process. Here is an excerpt from her page describing how she post-processes her work:

Quote:

I start by chasing and retexturing the stems that were used for bronze infiltration, using hand and power tools. Then I oxidize the bronze to a nice brown color, using heated sulfur and ammonia compounds to darken it. As you might imagine I can't do this part indoors, since it develops some remarkably unpleasing odors. I keep the steel from rusting by using very hot dips and drying immediately with a heat gun, so the metal isn't wet for more than a few seconds at a time.

Next I remove most of the oxidation by tumbling with abrasives, which smooths the corners and the roughest parts of the texture. This also brightens the high points, while leaving color inside the texture.

Lastly a burnishing tumble with steel shot puts a shine on the piece, followed by a light oil dip to seal the surface.



These seem like words of wisdom to those of us (again, like me) who have been thinking of our metal prints as rustproof.


------------------
Elytra on Shapeways: http://www.shapeways.com/shops/elytra
Re: Stainless issues. [message #8438 is a reply to message #8437 ] Sun, 20 December 2009 05:04 UTC Go to previous messageGo to next message
avatar derekh  is currently offline derekh
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I get that Shapeways is big about providing the all in one experience, you upload your design, it gets printed, and you are done. But in the case of the jewelry, well, it isn't done. I have to go and find a place to make a mold, then pour a wax, then get that cast in a material that I can wear.

If you look at the models, there are a ton of items that are jewelry, and I don't know about you, but if I make something, I want something I can wear. I am not going to wear a plastic ring, nor one that rusts on my finger. And with the technology out there to make super high resolution waxes, it seems like a waste to not have that.

Bottom line is if you are using Shapeways to get a product, and it isn't jewelry, yeah, you can get a finished product. If you want jewelry, real wearable jewelry, you have two to three more steps you have to go through.

Don't get me wrong, the detail on the print I just got is crazy awesome, and will make a great mold, but if they could cut that step out, cut out the wax pouring, that would really cement a great place for people designing their own stuff. And probably would result in higher traffic from others as well.

So how about it Shapeways, we going to get the wax printing anytime soon or what? Cause if you can do that at a decent price, you are going to get a ton more business out of me, and probably out of a lot of others as well.
Re: Stainless issues. [message #8440 is a reply to message #8438 ] Sun, 20 December 2009 06:28 UTC Go to previous messageGo to next message
avatar Wolfdagon  is currently offline Wolfdagon
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I am curious if a steel pendant would also rust like this and stain the skin of the wearer, since it is not in constant contact with the skin in the same way a ring is.

I placed an order for my first designs about a week ago. Like you, I just assumed that since it is stainless steel that there would be no problem.

I would assume that if I wanted to gold plate or silver plate the items that it would take care of this problem, but how thick would the plating need to be to be durable?
Re: Stainless issues. [message #8469 is a reply to message #8440 ] Mon, 21 December 2009 12:27 UTC Go to previous messageGo to next message
avatar robert  is currently offline robert
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Hi,

All stainless steel models we print oxidize. We do apply a clear coating on them before delivery but this will wear out at some point or is removed by any grinding or postprocessing.

As a tip I heard that people have successfully applied nail polish on the inside of a ring to prevent the staining.

Best regards,

Robert

[Updated on: Mon, 21 December 2009 12:28 UTC]

Re: Stainless issues. [message #8473 is a reply to message #8436 ] Mon, 21 December 2009 14:16 UTC Go to previous messageGo to next message
avatar aeron203  is currently offline aeron203
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I've been wearing a printed ring every day for a couple of weeks now. I did notice that if I sleep with it on, it would leave a mark. Otherwise it has been fine.

It's tough to compare this with traditional jewelery since the cost is a tiny fraction of what it takes to get a casting in precious metal polished to perfection. You have choices along a spectrum of materials and price to choose from as your design improves. If the piece is so important to you that you need to wear it all the time, it would make sense to at least coat or plate it.

I think what we have to gain from this conversation is that there is a high demand for metal finishing options. Here is my guess as to what it might cost in a price-per-volume scenario:

Polished Stainless - $10/cc
Extra polished- $15/cc
Copper/Nickel Plated - $25/cc
Silver Plating, fine polish - $35/cc
Gold Plating, fine polish - $40/cc

It isn't unreasonable to say you can make a ring with about 2cc of material, which would still be an excellent value for a durable custom metal ring. I have no problem with the appearance of the stainless material now, but coating options seem like a simple way to add a lot of value. The value increases about 4x and it is still workable. Hmmm.

Whoever decides to provide the service, please hurry. I'm just a designer and have no desire to mess with acid and cyanide. I drew the line at polyester resin.


Aaron - 40westdesigns.com/blog
Re: Stainless issues. [message #9089 is a reply to message #8436 ] Tue, 19 January 2010 03:46 UTC Go to previous messageGo to next message
avatar torrey.smith  is currently offline torrey.smith
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This is my first technical post, so bear with me Razz

I would look into Titanium Nitride (TiN) coating your parts.

If it can be done to the rapid-prototyped Stainless, it would give a gold-colored finish that is very hard and bio-compatible.

Typically, prices are on a per-lot basis, so it might be more cost-effective to do a bunch at a time, or simply ask if they can throw it into a lot they already have planned.

A local vendor might be more amenable to this, especially if you can pay cash.
Re: Stainless issues. [message #9093 is a reply to message #9089 ] Tue, 19 January 2010 12:00 UTC Go to previous messageGo to next message
avatar derekh  is currently offline derekh
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Thanks for the suggestions everyone, but here is what I ended up doing.

I had my stuff printed in the white detail, sanded it, it is being molded, and we will pour waxes from that. Would have been much easier to just order the waxes, but thems the breaks.

I haven't yet gotten the wax I need yet, so I am still hoping someone can chime in there with a wax that will work well with a silicone mold of my rings.
Pickling and passivation: Stainless issues. [message #10350 is a reply to message #8436 ] Tue, 02 March 2010 15:09 UTC Go to previous messageGo to next message
avatar bitstoatoms  is currently offline bitstoatoms
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Not sure if anyone has tried this, but with regular stainless steel fabrication there is a couple of processes to prevent and repair 'tea staining' which is the term the industry use for the brown discoloration we call rust.

"Stainless steel can corrode in service if there is contamination of the surface. Both pickling and passivation are chemical treatments applied to the surface of stainless steel to remove contaminants and assist the formation of a continuous chromium-oxide, passive film."

so usually it is the external chromium-oxide layer that acts as a protective skin, the smoother the finish, the better the protection.

Pickling is the removal of any high temperature scale and any adjacent low chromium layer of metal from the surface of stainless steel by chemical means.

Where the steel has been heated by welding, heat treatments or other means, to the point where a coloured oxide layer can be seen, there is a chromium depleted layer on the surface of the steel underneath the oxide layer. The lower chromium content gives lower corrosion resistance. To restore the best corrosion resistant performance, the damaged metal layer must be removed, exposing a fully alloyed stainless steel surface. Mechanical removal may leave abrasive or other particles embedded (interfering with corrosion performance) or may be impractical, so chemical means are usually employed.

Procedures incorporating pickling solutions of nitric (HNO3) and hydrofluoric (HF) acids remove the scale and the underlying chromium depleted layer and restore the corrosion resistance. Pickling solutions also remove contaminants such as ferrous and ferric oxide particles. Pickling solutions other than mixtures of nitric and hydrofluoric acids exist and can be used for specialised applications.

Pickling pastes, where the solution is mixed with an inert carrier, are commonly used to treat selected areas such as welds.

Pickling involves metal removal and a change or dulling in the visual brightness of the metal.

Electropolishing is a useful alternative to pickling. Metal removal is achieved, but usually results in a bright, smooth and more highly corrosion resistant finish.


Passivation is the treatment of the surface of stainless steels, often with acid solutions (or pastes), to remove contaminants and promote the formation of the passive film on a freshly created surface (eg through grinding, machining or mechanical damage).

Common passivation treatments include nitric acid (HNO3) solutions or pastes which will clean the steel surface of free iron contaminants. Care must be taken in selecting and using passivation treatments to ensure the selected treatment will target the contaminant. Passivation will also aid in the rapid development of the passive oxide film on the steel's surface. Passivation does not usually result in a marked change in appearance of the steel surface.




http://www.assda.asn.au/index.php?Itemid=103&id=78&o ption=com_content&task=view
http://www.assda.asn.au/index.php?option=com_content&tas k=view&id=85&Itemid=111


Duann Scott

Re: Pickling and passivation: Stainless issues. [message #10381 is a reply to message #10350 ] Wed, 03 March 2010 00:42 UTC Go to previous messageGo to next message
avatar GlenG  is currently offline GlenG
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The printed stainless material provided by Shapeways is very very different than cast rolled or forged stainless materials. It is a composite of alloy 420 SS and a bronze alloy. It is produced in a sintering process and for several reasons does not respond to to passivating like common SS materials. Close contact to human skin like what happens when you wear a ring, will always be a source of corrosion unless a barrier coat of some sort is applied. Other forms of jewelry like pendants and bracelets would be less troublesome as the skin contact is not as intimate. So, for rings a clear lacquer would be the easiest cheapest way to create a skin barrier but it will need to be recoated regularly. The frequency will depend on the individual ring wearer. A more permanent though more costly solution would be gold plating. But keep in mind that gold plating is an incredibly thin layer so even this will eventually wear away. The titanium nitride coating sounds promising and more durable but have no idea of the cost, especially on a "one shot" basis.


"Where the spirit does not work with the hand, there is no art."
Leonardo da Vinci
Re: Stainless issues. [message #10491 is a reply to message #8436 ] Fri, 05 March 2010 22:48 UTC Go to previous messageGo to next message
avatar berky93  is currently offline berky93
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That happened to me for a while when I got my ring. I got a rough sponge and rubbed the inside very vigorously (it wont damage or change the size of your ring at all, dont worry) and then after a week or so the darkness stopped appearing. now it doesn't happen anymore.
Re: Stainless issues. [message #10495 is a reply to message #10491 ] Sat, 06 March 2010 01:01 UTC Go to previous messageGo to next message
avatar bitstoatoms  is currently offline bitstoatoms
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Wow. How long have you been wearing it since

but if that works you would have to 'break in' every ring before selling?

Thanks for the tip


Duann Scott

Re: Stainless issues. [message #10500 is a reply to message #10495 ] Sat, 06 March 2010 04:27 UTC Go to previous message
avatar berky93  is currently offline berky93
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I wear it every day pretty much. And since you can't come into contact with your products before theyre shipped to the customer, you're probably best off just putting a note in your description if you want them to know.

 
   
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