Monday, March 4, 2013

Durability of Unusual Finishes: Chrome Plating and Clear Powdercoat

Wintry Bella Ciao
This winter I've been riding some bikes with unusual finishes. My main ride is a clear powdercoated Brompton. There are also two chrome-plated bikes in my possession at the moment: a vintage Raleigh Tourist and a modern Bella Ciao. The idea of riding these bikes on salted winter roads has been met with some concern, and I've been asked to comment on how they are holding up.  

To start with, I just want to say that chrome plating and clear powder coat are entirely different finishes, and I am by no means placing them in the same category. But the one thing they have in common is that they are unusual, which invites curiosity about their durability compared to paint. Unfortunately, I cannot address that question meaningfully. I didn't have the heart to experiment with the beautiful finishes, so I've been cleaning the bikes after every salty ride this winter. But in truth I am not sure how much this extra care is warranted. 

When it comes to the chrome plated bikes, I am actually surprised by the concern for their durability. Chrome plating might be pretty, but its real purpose - as I understand it - is to make the frame more resistant to corrosion. Therefore, a chrome plated frame should require less, not more maintenance than a painted or powdercoated frame. Issues of cost aside, chrome plating should make for an excellent and entirely appropriate winter bike finish. For what it's worth, my chrome Raleigh Tourist is a 33-year-old bike that was well-ridden by its previous owner. The chromed frame shows less wear than a typical painted frame from that era, though a similar degree of component wear. 

Clear powdercoat is a different story. Generally speaking, powdercoat is considered to be a more durable finish than liquid paint, which makes it a preferred choice for winter bikes. But clear powdercoat is tricky and may not be reliably rust-proof. Owners of clear-coated bikes have reported problems with corrosion. Rivendell used to offer clear-coated frames, but no longer does. Brompton at some point reformulated their raw lacquer finish to address corrosion issues. Today there are owners of clear-coated Bromptons who ride them in winter, and dealers seem to feel this is perfectly fine to do. I do not see any signs of rust on mine so far, although again - I've been cleaning it. I would not intentionally choose a clear powdercoat finish for a winter bike. 

All things considered, I feel that (pigmented) powdercoat and liquid paint are more practical choices for a bike finish. Chrome plating is expensive and difficult to do properly. Clear powdercoat is reputed to be less durable.   

Then again, there are bikes that do perfectly well with no finish at all. As an experiment, Henry Cutler of WorkCycles left his personal Fr8 frame unpainted. For three years the bike was stored outdoors in Amsterdam's rainy saltwater climate. Over time the frame has developed a patina of surface rust, but it remains structurally fine. Go figure!

49 comments:

  1. You don't know his bike is structurally fine. No one does.

    Too general a comment - all kinds chrome plate - some sucks, some is OK. Chrome isn't an exact metallurgic composition.

    Not all paint is equally durable either, you should know that.

    Finally, you can't begin to assess long term durability of these finishes in the span of a couple of months, bikes not even ridden daily in salt, but for the brompton.

    I'm disappointed you don't see variation within each finish.

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  2. Back in the 80s I remember chrome-plating for BMXs was the duck's nuts. Some weight-weenies complained it added unnecessary grams, but it looked amazing. And still does. Those chrome-plated Herse randonneurs... mmMM! But the difficulty is finding someone nowadays who can do a good job. No. Correction. Finding someone who can do a passable job. I have components ruined by well-reputationed chrome platers. It seems they don't generally work to fine enough tolerances for bikes. The ones around my neck of the woods anyway.

    An all-chrome frame is still a thing of beauty and it is interesting to hear that your Raleigh's frame has worn so well.

    b

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  3. Interesting comments as I have just built a commuter frame for myself that will be clear 2 pack wet sprayed. It will be interesting to see how it holds up. I like interesting frame coatings though, I have a copper plated bike, a gun blued bike, and I had a vintage Hercules with bare metal that I coated with beeswax... needless to say that was not the most durable.

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    1. Did you have the frame hot bath blued or did you use one of the "cold bluing" products? I always thought a blued frame would look great though I had some doubts about the long term durability of the finish. Parkerizing might be interesting too :-)

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    2. I cold blued it and then coated it with beeswax, still looks pretty good after 2 years. It is a dry day bike though. The finish looks fantastic, you can see all the brazing through the colouring. There are some pics of it on my blog somewhere; http://pogwardbicycleindustries.blogspot.co.nz/ I also forgot to mention my zinc plated bike as well, although that is just a frame right now.

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  4. Chrome has developed a bad reputation over the past 20 years. This is mainly due to the fact most 'premium' bikes have gone over to aluminium and composites because they're lighter than steel. Consequently in recent years only very cheap bikes came with chrome bits and because they're cheap bikes the chrome finish is cheap too, so it doesn't offer great protection to the steel substrate. A good quality triple plated finish (layer of copper, layer of Nickel and a layer of chromium) should actually be slightly more durable than enamel paint. British standard Chrome plating is a slightly higher standard than US standard and far superior to far eastern standards.
    Clear powder coat is still as hard wearing as coloured powder coat, however the difference is that coloured powder coat generally has a rust inhibiting primer applied underneath it giving an extra layer of protection.
    Bare steel will eventually rust, but the quality and thickness of the steel plays a big part in how long it takes to rot through, look how long railway tracks last.
    Also most steel these days is given a phosphate coating, which will prevent rust for a while if left uncoated, the idea is to stop the steel stock going rusty in storage before it's actually used to make in this case a bike frame.

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  5. I have a theory that clearcoated bikes aren't really more prone to rust. Perhaps most steel bikes develop a little light surface corrosion under the paint, but under the opaque colors it goes undetected.
    -Matthew

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    1. Agree. Out of sight, out of mind as they say.

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  6. Interesting about the unpainted bike. Lots of architectural uses of steel call for no painting, and I'm guessing it's because when steel is left unfinished, it can develop a uniform layer of oxidation which becomes a protective coating (aluminum does this too). The key here is that there's nowhere for water to become trapped; the surface of the steel can dry out and not retain water. Contrast this to a painted bike, or a chrome plated bike, where the paint or chrome develops a chip. Water gets down beneath the chip, and accelerates oxidation. This eventually lifts the plating (or paint), forming a rust blister. The blister continues to grow because it continues to trap water inside it. I'm guessing that since Henry's unpainted bike cannot develop flakes in the finish, there's no way rust blisters can form. Just a nice, protective patina.

    But it's also true that the chromium content in chromoly steel helps resist oxidation more than other steel formulations, or so I've heard.

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    1. Those architectural steels intended to be left unfinished usually contain copper as part of the alloy. As far as I can discern this also decreases yield and tensile strength and makes them less suitable for drawing them into tubing than the alloys usually used for bicycle frames. Stainless steel contains a high enough portion of chromium that it forms a film of chromium oxide which prevents corrosion from progressing. Chromoly steel doesn't have enough chromium to do that but it does resist corrosion better than some steels.

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    2. Rusting is a fundamentally different process than aluminum corrosion. I remember seeing illustrations in a material science class of how aluminum oxide forms a stable surface layer, but rusting iron actually pulls material away from the surface and flakes off, revealing a fresh, rustable surface.

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  7. I think that, as far as corrosion of steel frames goes, the quality of the steel is at least as important as the finish.

    I've never owned a clear-powdered frame, but i've seen quite a few and they do tend to show more rust than one might expect, given the vintage and use. I suspect that visibility is a factor; pigmented powder does a great job of hiding any blemishes, but they do exist in there.

    Chrome plating. They don't make it like they used to. I'm a bit fuzzy on the details, but in the States at least, the EPA changed up requirements. Better for the environment, but worse for bike frames/components. This is why quality chrome stuff from bitd shows little pitting and polishes up perfect, while new chrome gets surface rust quickly and doesn't polish easily without "clouds".

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  8. Proper prepping is critical for a good chrome finish. For paint as well, but paint prep is less expensive. No surprise then that chromed bikes and parts have moved from the mainstream to niche.

    Bad chroming fails pretty quickly. A lot of once shiny bikes have been recycled. Perhaps your refrigerator frame was once a stack of Gitanes.

    On the other hand, good chroming will endure many hardships with aplomb. Appears your Raleigh was done right.

    My raw stainless is holding up well. I rub it down with a fine scotch bright pad after riding in the muck. If only I and my clothes cleaned up so well.

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  9. Wow! I've never seen a chrome-plated bike before; that is STUNNING!

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  10. Are you doing simple things like dropping the wheels to clean the underside of the fenders? What are you doing to clean beneath the various fender hardware? How often do you disassemble the chaincase to get the salt out of there? Those are a few of the easy ones.

    You seem to operate on the principle that if you have not experienced something yourself the experience of others may largely be disregarded. That is approximately normative behavior. The experience of others does however have value. Collectively we experience far more than any one individual can. How I should report my experience to you so that it will mean anything at all to you is beyond my limited comprehension. It is always difficult to share experience.

    Chrome is nearly purely binary. It shines or it doesn't. Small rust spots show.

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    1. "You seem to operate on the principle that if you have not experienced something yourself the experience of others may largely be disregarded. "

      Not at all. In the post, I write that "I cannot address that question meaningfully" precisely because my experience is so limited. Instead I offer a discussion and some background, and the comments are for others to share their experiences.

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    2. I am not a ferrous metal. I am not free oxygen. I am not a hydroxyl radical. So I have no more direct experience of rust than anyone else.

      If you want to crowdsource opinions that in the presence of moisture and a good supply of cations rust does sometimes take a nap you can give it a try. You won't learn much that way.

      All steel finishes fail. They fail in different ways and at different speeds. Exceptional finishes - chrome - show the damage more conspicuously than would flat black. When the bloom is off the rose you can't get it back.

      Oxalic acid is useful. It does not reverse the process or turn back the clock. Time flows in one direction only for all practical purposes.

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  11. Chrome is probably not as good as you think -- it's shiny, but electrochemically it is the wrong choice. If you get a chip in it the steel nearby will be preferentially corroded.

    I'm not sure what Surly uses for a finish, but my bike has survived several winters without much attention. There's problems near the chaincase standoff, and the finish wore off where a brake cable rubbed the frame, but otherwise it's fine. I did pre-tape all the cargo-exposed tubes in back, both to protect their paint, and to reduce the chance of glass bottles (beer, wine) clanking hard into steel.

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    1. "Chrome is probably not as good as you think -- it's shiny, but electrochemically it is the wrong choice. If you get a chip in it the steel nearby will be preferentially corroded."

      That's the point though, chrome is very hard and when done properly very hard to chip/scratch through to the steel. Like almost any protective coating though, whether it's paint, plating or lacquer it seals the steel from the air, once the coating is compromised and the steel is exposed to the air it will rust.

      About the only thing that doesn't is Zinc Galvanising, but that doesn't exactly look pretty.

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    2. Surly powdercoats their frames. My experience has been that it isn't terrible,but it chips more readily than some other PCed frames I've owned. I'd give it a c+, maybe a B- at best.

      Personally, I think a zinc-gal frame would look rockin'.

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    3. I know nothing about chrome plating, but I know that I've seen original chromed finishes on 50 year old bikes that look like new. And I've seen chromed finishes on almost new bikes that look thin and chipped already.

      Why are many hand tools (sockets, for example) chrome plated? They make contact with other metals under high torque, so the finishes must be hard. I have chromed tools, some of which are 20-30 years old and have seen a lot of use, and they still glisten when wiped clean.

      Indeed, it has to do with process.

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    4. Just a couple of months ago I looked into having a frame hot-dip galvanized. Not so easy. All tubes would need openings of at least 3/8 inch at both ends to facilitate draining of the molten zinc when removed from the tank. Because dip temp is 850F, no closed tubes allowed because of fear of explosion or distortion caused by any trapped moisture. Also, the coating would end up thick enough that machining would be required post-dip to get the crank and head bearings to fit and any threaded holes would need to be redrilled and tapped, etc.

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  12. My current ride, a prototype 650b Stag all-road without finish looks splendid with a slight patina:

    http://rawlandcycles.blogspot.com/2013/03/seans-20-pound-stag.html

    Sean

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  13. The clear powdercoat that I use is supposed to be about the most durable/corrosion resistant option from the source where I get that sort of thing. It's rated for 3,000 hours of direct exposure to salt water with zero effect if I remember correctly. As soon as I get a big enough oven finished I'll be clearing a couple frames that should look neat "nekid". I've done a pile of other, smaller, components with it already and they are holding up fine.

    I've had a bunch of bikes with chrome frames and or forks, and a good coat of car wax and a little basic TLC are all that's needed to keep rust at bay. I have a 30 year old Mongoose I got in High School that has absolutely fabulous chrome and it didn't even get that. YRMV...

    Spindizzy

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  14. My daily rider is a 45-year-old Bottecchia with a fully-chromed frame (polished only on the parts that were originally meant to show; we replicated the paint scheme). Ridden in rain but not snow (SoCal; salt air by the sea though). Pic

    My wife Gina had her MIyata chromed when we converted it to a kindasorta randonneuse; no problems in several years. Pic

    And a guy named Dennis has a 90-year-old bike that he rides along the salty Pacific Ocean bike path here every day; it is nothing but a mass of rust, yet holds a hefty gentleman up for his daily twenty miles with no fuss. Pic

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  15. Funny how that works...

    Chrome is indeed a highly variable process.
    Here is V's favorite cheap mountain bike frame after a light oxalic acid bath, an hour of chrome polish, and some Turtle Wax:

    1984 Mongoose ATB

    This bike spent at least 5 years chained up outside under a carport right next to a river and 1.5 miles from the Pacific Ocean. It should be knackered, but it is nowhere near done. The chrome on the headset cups is pretty well shot, though...

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    1. Stop taunting me with the Mongoose frame!!
      Thankfully, it's too big for me IIRC

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  16. I think your article leaves some room for confusion between clear powdercoat and what most people think of when they refer to clear coat, which is more like paint in formula and application. I always thought that the finish Rivendell used to offer was the latter. The only similarity between the processes is that the result is clear.

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    1. I could be mistaken, but I was pretty sure Riv's clear finish was powder. For instance, at the moment their paint menu uses the following phraseology:

      "Powder coating is the cheapest of all options at about $150 for a single color, frame & fork. No more clear-coats.

      Wet paint looks the best and is more expensive. Wet paint prices below..."

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    2. Hmm, well would you look at that. I just assumed that clear powdercoats were much more esoteric than clear enamels...

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    3. I think the rivendell clear coats were just that, clear coats of liquid paint to show off the raw metal

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    4. Maybe it was different with other models, but the raw look Protovelo Riv sold was clear powder coat.

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    5. Grant called it, "Raw Clear Powdercoat". I think that's clear enough. :-)
      Whether it's more durable or not, it is more inspectable. If rust develops under the powdercoat, you can see it.
      Ever seen a bike with blistering paint that as it chips away shows rust underneath?

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  17. Right now I'm working on a '62 Raleigh built 3speed, full chrome. It has B-line badging but it's hardly a B-line. Forkends filed better than some 40s or 50s RRAs I've seen. Special touches everywhere. It appears to have been brazed with a torch and not on the Raleigh hearth. Looking at the chainring tells me the bike has done maybe 100 miles. As far as I know this bike spent 50 years hanging on hooks in a garage in Costa Mesa California. Dry climate.

    It has rust. Not bad, but rust. Wide spaced light peppering. From 5 feet away in the sun the bike is just blinding. Put it on the stand and look and it has rust.

    Your '80 Raleigh does not have better chrome. It is not invulnerable. Treat it as if it's invulnerable and you will rust up quick.

    Someone, some fallible human, has to prepare each piece of metal for plating. Some mistakes or omissions will not matter and some will weaken the plating. The plating does not go on absolutely uniformly. It matters where the electrodes are. It matters where the next piece in the tank is. Edges and rough spots matter a lot. Any piece gets nickel plated and then polished. By hand. Then it gets copper plated and polished. By hand. Then comes chrome plate and final polish. By hand. The same high spots will tend to be polished away to zero each time. Chrome does not absolutely and uniformly encapsulate. There's no way ever to know how uniform or thick chrome is. Don't start me about the acids used in the process.

    Basically all you ever know is the reputation of the plater. Raleigh did good plate. For production work there was never better. They were consistently better than some constructeurs. But not perfect. Your bike is not perfectly protected from the elements. Your chrome has thin spots and weak spots and flaws and it did fresh from the factory. Sooner or later those flaws will show. Coating the steel in road salt is an ideal way to accelerate the process. Removing road salt is not accomplished with a quick wipe or even with a trip to the car wash.

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    1. "Removing road salt is not accomplished with a quick wipe or even with a trip to the car wash."

      I think i'm right in saying that using plain water can actually dissolve some of the salt and wash it into crevices. Most car shampoos contain neutralising agents though

      A good regular coating of metal polish though, leaves a protective layer of wax/resin on the metal, which apart from the cleaning is what further protects the finish.

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    2. Plain water dissolves salt and that may be as good as you get. Absolutely salt will be washed into crevices. Crevices less accessible to wax or resin than to saline solution.

      Neutralising agent? Refresh me on the chemistry of that. Sounds more like a sales pitch than anything I'd trust. Whatever the reagent the products of the reaction have to go somewhere and I don't see how they would be anything benign.

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    3. Well i'm not a chemist and have never claimed to be. However if you google "Salt Neutraliser" you'll see it's used in various industries, hard to imagine it would be so widely used if it wasn't effective.

      As for crevices then a dose of Dinitrol (or similar) cavity wax (as used on cars) creeps into voids and prevents (stops) corrosion. Spray it on/in allow it to creep in then wipe off the excess.

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  18. I saw a mouthwatering vintage Trek touring bike that the owner had had nickel plated. Similar to chrome, but a little warmer finish. Oh, was it gorgeous. It lived in Texas though, so probably didn't get much road salt....

    I've heard that typical methods of Chrome plating have changed over the last 30 years to comply with environmental standards, and that the new, more environmentally friendly chrome is less durable, but I'm not sure that there's any truth to that.

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  19. Powder coating is NOT rust proof. The coating itself is very durable, but without underpainting once a frame gets scratched it's corrosion city! I had this happen with my surly and was upset by how many corrosion spots there were just from normal wear and from the front derailleur clamps. Liquid paint at least offers several layers of protection.
    Chrome plating is something to behold and at one time it was common for bikes to be chrome plated. High end italian bikes were still chromed, may still be for all I know. Beautiful! Yet the newer de salting materials such as magnesium chloride will eat at anything.

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    1. "Powder coating is NOT rust proof. The coating itself is very durable, but without underpainting once a frame gets scratched it's corrosion city! I"

      No coating is, because it's not the coating that rusts it's the steel substrate. If you scratch through to the steel then air will get to the steel and the steel will rust, eventually the rust will break the bond between the coating and the steel. Which is where you get sheets of the coating start to flake off. Galvanising (with Zinc) has a degree of self healing from chips and scratches, but even then if you scratch enough off the steel will rust.
      So the key thing is to make the coating hard wearing, Powder Coat and Chrome are both very tough, but can still be breached with enough abrasion or impact. Both come in different qualities, thin powder coat or chrome will be little better than conventional wet paint.

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  20. A few ppl have mentioned auto wax and metal polish, etc... What's the consensus view as to what is best for keeping chrome intact? I'm about to go buy some of it, whatever it is...

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    1. High grade carnauba wax. You will not need a whole lot, so might as well go with the best.

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    2. The smallest can you can get will last longer that the shelf life of the wax, unless you have a large herd of bikes to treat... hmmm... (justification!)

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    3. I don't even own a chrome framed bike, but I do have some chrome bars, forks, cranks, headsets, etc. I'll crab some carnauba wax asap, along with some cheap-but-good automotive bearing grease.

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    4. Matthew has it right. Plain Johnson's Paste Wax is carnauba and cheap. Same stuff as automotive/aviation wax. You want it thin. It dries harder quicker if it's thin. Add a few drops of paint thinner to top of the block of wax and wipe a thin coat. Some of the ten times higher priced product does have additives that might do something. For bikes one package should last a long long time.

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    5. Metal polish (like most car polish) has a fine abrasive in the paste which cleans the surface as well as removing minor scratches. The wax/resin content in the polish is what is left behind to protect the finish. If chrome is grubby with minor rust specs then metal polish will bring it back up like new. But using it too often will eventually wear down the coating through abrasion. If the coating is clean and relatively bright then a good plain wax is best with regular use.

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  21. My Tout Terrain Silkroad was powder coated and has shown excellent durability. My custom built "light touring" bike was painted "clear coat". I have been disappointed. It shows significant wear after less than one year. BTW, I treat my bikes carefully and they are stored in a garage. I do ride year round here in Rhode Island so lots of sand and salt.

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  22. Of course if we're going to talk about "unusual Finishes" Then this has to be one of the most 'unusual' i've seen.
    http://www.vanheeschdesign.com/?p=17#more-17 A copper plated bike, which with age develops it's own green patina. They also do a brass plated bike. You can even buy matching chain locks.
    Finally with the ultimate in 'durable' coatings, they make a galvanised "Zinc" bike too!

    Although the one retailer i found in the UK selling the copper version has it listed for about £3600! ($5400ish)

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  23. http://revanchebikeco.wordpress.com/2013/12/21/29er-good-fillets-are-a-thing-of-beauty/
    http://revanchebikeco.wordpress.com/2013/12/21/maras-bike-part-4/
    http://revanchebikeco.wordpress.com/2014/01/11/maras-style-cruiser/
    I do some frames with a 'golden' clear powdercoat, it's been pretty tough so far, the latest ones have a two part clear coat over the clear powder.this lets me use decals.
    Preparation is key, and it's a long process, as even the sanding marks have to be the same size and direction.
    looks gorgeous out in the sun, all the fillets shine.

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