I want to commend Jim on this excellent summary. I know a bit about chroming from my days as an armament engineer and from having one frame re-chromed.
A point to understand about chrome is that the acids attack (during the preparation and any electropolishing) and the crome plating builds up proportional to the electric field. The electric field is weak in enclosed areas (like the seat stay and chain stay joints) and strong at sharp edges (outer lug edges). Thus plating can be too thin in the weak field areas and poorly prepared sharp edges can have chrome buildup. This can all require a lot of polishing, manipulation of electrodes and finesse for a good job. Many older frames, for example, show surface rust at the thinly plated chainstay and seatstay areas. Understand or caring about how to chrome a bike frame is probably beyond the capabilities of most "bumper shop" platers.
There is also the issue of hydrogen embrittlement causing cracking. This is somewhat dependent on the chroming process but is best remedied by a baking cycle (12 - 24 hours at 300 F) after chroming. Or you can do what I did which was to wait a year at room temperature before riding the frame.
As to my personal experience with having a frame plated, I balked at Jim's prices for chroming and went to an auto restoration house at about half Cyclart's price. They did a nice enough job and I was careful to take the extra step of neutralizing the inside of the frame and coating it with rustproofer after the chroming. The interesting thing is that they said they would never do a frame again! That was because of the polishing danger described by Jim. I got the impression that someone was seriously endangered while polishing the frame. I also got the feeling they regarded it as a money loser.
So the gist of all this is to carefully consider the chroming decision and be prepared to pay above the bumper shop price to get it done right or get a second frame done!
Joe
Still waiting for all the re-nickled parts for the Brennan Special that will be at the Cirque next year. All genuine BSA equipped, highly modified Brampton lugs, Reynolds high manganese tubing and a Lycett Swallow saddle- almost British. I have seen nickled and chromed Brennan frames too.
At 09:47 AM 5/15/01 -0700, Jim Cunningham wrote:
>Brandon asks about chrome, what is possible; costs and is it good as "old"
>chrome...
>
>CyclArt has offered complete bicycle frame plating services since 1979.
>With the exception of a transition three years ago we've worked with a few
>very talented and hard working platers who have taken the time and made the
>investments necessary to first class results on bicycles. A great plater
>of auto parts can do a terrible job on a bike frame. Race frames present
>serious challenges to platers. First, stripping old chrome involved use of
>strong acids which can excessively remove brazing material. Frames have
>areas like for blades, seat stays and top tubes which often have small vent
>holes or even pinhole gaps in brazing. These are especially troubling
>because in the plating bath, electrical current will "draw" plating
>solutions into these spaces, but once out of the tank the liquids will not
>come out, that is until they "eat" their way out. The tendency for frames
>to trap solution internally is a prim reason why many conscientious platers
>will not work on them. Their concern is that the frame can "drag"
>solutions, carrying them from one tank into the next. A few parts per
>million of such contamination can both render a 500 gallon tank to useless
>toxic waste and incases of a rinse tank cause toxins to discharge to the
>sewer system and cost potentially mean a large fine or closure by
>regulators.
>
>It's true that we rarely sue a copper base layer anymore. There are several
>reasons. One is that the copper tank is not the worst source of toxins.
>The other is that unless the frame is badly pitted or rough we don't believe
>it is a good thing. Given proper care and procedure, the nickel plating
>which preceeds all chrome plating will give excellent beauty and protection.
>The idea with copper is to build a thick soft base layer which is easier to
>polish. While it can help fill pitting, the downside is that the copper
>adds unnecessary weight and thickness, in fact, unless care is taken
>threaded and press fit surfaces will all be compromised. So while many
>platers complain about how the "new" techniques don't give the results of
>the old, we think fine results can still be had, it's just a little harder.
>
>Another factor is the labor in polishing frames is challenging. Lugs are
>soft material, tubes are hard. It's difficult to keep the lugs crisp and
>sharp when doing a full chrome frame, especially as is usually the case,
>there are rust pits to polish out. Also efficient polishing requires
>horsepower. Most platers use wheels with 12 for 25 horse power motors,
>running at 1260 RPM. A mistake that causes the buffing wheel to catch
>between the stays and seat tube can result in severe injury. Then there are
>the hazards of exposure to strong acids, heavy metals, dusts and high
>voltage. Platers earn hazardous duty pay! Meanwhile, most quality plating
>shops have a clientele of motorheads who throw thousands of dollars at the
>chrome on their projects, which rarely present the hazards of our bike
>frames!
>
>So, we are grateful that we can still offer a full range of plating
>services! Our listed prices include the charges necessary to prepare the
>area around the chrome for painting, to mask and unmask. To review our
>price list go to:
>
>http://cyclart.com/refinishform3.html
>
>or to our home page:
>
>http://cyclart.com/
>
>Thanks!
>
>JFC
>CyclArtist
>Vista, CA