I wrote this article for the 356 Registry a while ago, late 90's to be exact, I hope it helps. It was used for a 1957 Porsche, obviously the later cars, like my 230SL have Yellow Cad or Zinc Chromate but the key is in preparation. Garbage in - Garbage out.
By Ron Scoma
Call it what you will, Obsessive-Compulsive Disorder, Anal Retentive, being a craftsman, or just plain having no life; this is what I did to Cad plate stuff.
1. Make a list of all items to be plated.
2. Find the parts in the Bucket O' Stuff and count the items.
3. Soak in orange cleaner to somewhat degrease, rinse.
4. Soak in Carb Cleaner to really degrease, rinse.
5. Soak in Muriatic acid to remove prior plating.
6. DON'T let the acid come in contact with aluminum (tin foil) trays, I'm not sure why you shouldn't but the end results were very bad. You may not have a screaming S.O. shouting "where's the checkbook, I need to increase your life insurance ?" but still, even without that bonus, the effects were pretty bad. Neighbors in the unit next door were curious also...
At this stage you have parts free of grease and oil.
7. Blast with 180 grit AO (aluminum oxide) to even out the surface. (I used barrel blasting for the fasteners).
8. Chase all threads with an undersize tap/die. You want to clean the threads, not remove metal.
9. Blast with the equivalent of 280 grit glass to produce an even sheen for the Cad.
10. Bring to plater. You have already identified a plater that;
a) will do Cadmium 1 or Silver Cad.
b) will do Cadmium for YOU if your company name isn't Boeing or McDonnell-Douglas.
c) will not lose most of your parts.
d) you can afford.
To do a bucket (a gallon paint can or so) of fasteners (2 complete engines), 6 fuel lines, 3 crank pulleys, 3 generator pulleys, 2 generator cases, 4 valve covers, 3 dipsticks, etc., etc., etc., was $200 cash in the Chicago area. All-in-all, not too bad for the upgrade in cosmetic appearance in my opinion. Add that to a little powder coating, a little epoxy coating (heater boxes and fan), a little VHT (muffler system) paint and you have a pretty nice looking engine. Do not plate heat treated (black) fasteners.
Final Tips:
Cadmium can be removed by muriatic acid (better to plate and remove, then not plate enough). Everything must be oil and grease free. Fasteners will be lost, have extras. Surface preparation is next to Godliness (repeat 10 times).
DON'T BLAST ANYTHING THAT WILL COME IN CONTACT WITH THE OIL SYSTEM.
DON'T BLAST ANYTHING THAT WILL COME IN CONTACT WITH THE OIL SYSTEM.
and
DON'T BLAST ANYTHING THAT WILL COME IN CONTACT WITH THE OIL SYSTEM.
BE NICE to the plater. You will forget to bring him that one bolt or part that will be very visible necessitating a return trip. You don't want another minimum order charge...
Upon return of your parts...
1) Inspect EVERY part, if you're not happy talk with the plater about re-doing them.
2) Gently run the undersize tap/die through the threads to remove any potential plating that is where it should not be.
3) Sort. The EPC helps a lot with this part. I print and sort based upon M-B's part coding.
I would not spend too much time on washers and or lock/wave washers. Most are available from Metricmcc.com, one of their suppliers is Wurth BTW. Besides, you don't want to reuse lock or wave washers anyway.
Addendum (2016).
+1 With the advent of digital picture taking (phone/camera) keeping track of items is much easier. You will still need a paper notebook and pen.
+2 If I had to do it again I would drill some holes in aluminum or steel sheet to hold each fastener while blasting. Unscrew them a little to get under the head.
+3 The average engine will take about 10 hours of your time to prepare. But if it takes 15, so be it, it takes 15. If you got a date, cancel it.
+4 You need to inspect every millimeter of every part for thread condition and uniformity.
+5 Before going to the plater I wipe everything off with lacquer thinner and put them in a NEW bucket. I know the extra dollar or two for the new bucket will blow the budget but that's life.
+6 I would rack plate everything... that increases the cost substantially, bit it's the ONLY way to get a uniform appearance IMHO.
You MIGHT be able to convince the plater to wire the items yourself. Labor is a BIG cost and that will reduce his labor charges which he will, hopefully, pass along to you.
Also, YOU get to determine where "wire line" (from hanging) is shown. This is very important as you don't want it visible. The plater is probably not well versed in Pagoda originality to make that decision himself.
I like to know who I'm doing business with, the Internet makes it easy. Find out something about the company and the President, if he likes Scotch, bring him a bottle. I'm originally from Chicago and we're use to gifting people like Judges, Politicians and Bureaucrats for example - so why not the guy who does your plating? A small Bouquet O'Cash goes a long way, as does a handshake, with a 10 or 20 inside, to the guy doing the actual work.
Ron
